OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON , D.C. 20460

PC Code: 1 29026

DP Barcode : D 423306

Date: February 1 0 , 2015

MEMORANDUM

SUBJECT : Tebufenozide Drinking Water Assessment for Registration Review

TO: Christina Sche l tema

, Ch emical Review Manager

Avivah Jacob , Team Leader

Patricia Parrott

, Branch Chief

Pesticide Re

- Evaluation Division (7508 P)

Mohsen Sahafeyen

, Chemist

Donna Davis

, Acting Branch Chief

Risk Assessment Branch V I Health Effects Division (7509P)

FROM: J a m es N. Carleton, PhD, Senior Scientist

Environmental Risk Branch IV Environmental Fate and Effects Division (7507P )

REVIEWED Cheryl Sutton, Ph.D., Environmental Scientist

BY: Environmental Risk Branch IV

Environmental Fate and Effects Division (750 7P )

APPROVED Jean Holmes, DVM, MPH Branch Chief

BY: Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P )

EXECUTIVE SUMMARY

A screening

- level drinking water assessment (DWA) for tebufenozide was conducted in support of regis tration review

. Tebufenozide ( benzoic acid, 3,5

- di methyl

- 1

- (1,1

- dimethylethyl)

- 2

- (4

- ethylbenzoyl) hydrazide) is an insect growth regulator belong ing to the diacylhydrazine

class of insecticides that interfere wi th the binding of the endogenous steroidal molting hormone

20

- hydroxyecdysone with its receptor protein complex, inducing a precocious incomplete molt in insect larvae, particularly lepidopterans (Dhadilla et al. 1998; Shimizu et al. 1997).

Tebufenozide i s used as an insecticide on a variety of forestry, fruit, vegetable, orchard and ornamental crops

. Current tebufenozide labels include use s on bushberries, cane berries, canola, citrus, tree nut crops (almonds, pecans, walnuts)

, other nuts, brassica veget ables, cotton,2

cranberries, fruiting vegetables, mint, ornamentals, pome fruits, sugarcane , trees/forests/shrubs, and pasture/rangeland

.
The maximum annual application rate o f tebufenozide is for fruiting vegetables, mint and

ornamental uses , at 2.0 lbs a.i./ A

. T he maximum chronic and cancer surface water estimated drinking water concentrations ( EDWCs ) are associated with the fruiting vegetables use, however

the maximum acute EDWC is associated with the use on sugarcane at the lower annual rate of

1.0 lb s a.i./ A /yr

. The computer model s PRZM and EXAMS , as implemented in EFED’s Surface Water Concentration Calculator (SWCC)

, were used to generate surface water EDWCs for use in

the human health dietary risk assessment, while the Pesticide Root Zone Model for Groundwater (PRZM

- GW) and Screening Concentration in Ground Water (SCI

- GROW) models were used to generate groundwater EDWCs

. A Provisional C ranberry M odel was also used to generate

surface water EDWCs.

According to a memorandum from Mohsen Sahafeyen da ted October 2, 20 1 4 (D P

423156 ) , the chairperson (Christine Olinger) and a senior member (Ray Kent) of the Health

Effects Division ’s (HED) Residues of Concern Knowledge

- Base Subc ommittee ( ROCKS ) met with other members of HED and EFED on September 29, 1014

. The group concluded that

tebufenozide and its major degradates RH

- 112651 , RH

- 112703 and RH

- 96595 are Residues of Concern (ROC) in surface water

- derived drinking water

. Although the group could not ascertain that any of the t h ree degrades were less toxic than the parent, t he group concluded that in groundwater only tebufenozide and metabolite RH

- 112651 are of concern

, based upon the

rationale that because the other two degradates (RH

- 112703 and RH

- 96595) were below 10% of applied radioactivity specificall y in the submitted aerobic soil studies, these entities would not be expected to constitute “major” degradates in groundwater. However, after conducting a full exposure assessment EFED has included the parent and three degradates in the groundwater

assess ment. A Total Toxic Residues (TTR) approach was employed to model both ground and surface water, in which TTR comprises parent tebufenozide plus all three of its major

metabolite s ( RH

- 112651 , RH

- 112703 and RH

- 96595 )

. In surface water TTR was conservative ly

modeled as a single conceptual entity with SWCC and with the Provisional Cranberry M odel

, using an aerobic soil half

- life representing the degradation of parent plus all three degradates, and a soil sorption coe fficient (K OC ) reflecting one of the (more mobile than parent) degradates

, for which data were available

. Unlike surface water, g roundwater modeling ( using PRZM

- GW )

was “ refined

, ” by simulat ing parent and the three summed degradates as separate entities, then combining their resulting EDWCs to re present TTR.

The maximum EDWC values recommended for use in the human health dietary risk

assessment are 116.4 μg/L for acute EDWC and 107. 2 ug/L for chronic and cancer EDWC s

. For surface water sources of drinking water, th e maximum ( 1

- in

- 10 year return frequency daily )

acute EDWC

, associated with the use of tebufenozide on sugarcane (by ground application)

, is

51.8 μg/L. T he maximum chronic (1

- in

- 10 year return frequency annual mean) and cancer (long term mean) EDWC s, associated with the use of tebufen ozide on fruiting vegetables (by aerial application)

, are 3.13 μg/L and 2.19 μg/L respectively

. The maximum acute groundwater

EDWC from PRZM

- GW is 116.4 μg/L associated with tebufenozide’s use on fruiting vegetables, mint and ornamentals . T he correspondi ng chronic and cancer (long

- term mean)

EDWC from PRZM

- GW is 107.2 μg/L

, and the SCI

- GROW EDWC is 1.18 μg/L

. Surface water

EDWC s generated using the Provisional Cranberry Model are strikingly similar to the PRZM

GW result s , with a chronic value of 105.8 μg /L. These (cranberry model) results are presented3

for illustrative purposes only, given the model’s provisional status. The bolded values presented

in Table 1 are recommended for use in the human health dietary risk assessment. Selected

model results ar e provided in Appendix A

.

Table 1

. Maximum EDWCs of t ebufenozide T otal T oxic R esidues

.

D rinking W ater

S ource (M odel U sed ) U se (rates modeled) M aximum E stimated D rinking W ater C oncentration (EDWC)

A cute ( μg/L ) C hronic ( μg/L ) C ancer ( μg/L )

Surface water (SWCC ; LAsugarcaneSTD scenario, ground application for acute; FLpeppersSTD scenario, ground application for chronic

and cancer ) Sugarcane ( 4 apps at 0.25 lbs a.i./A, 10 day RTI ) ; fruiting vegetables ( 8 apps at 0.25 lbs a.i./A, 1 0 day RTI ) 51.8 3.13 2.19

Surface water ( Provisional C ranberry

M odel) Cranberries ( 4 apps at 0.25 lbs a.i./A, 7 day RTI ) 279.3 105.8  ̄

Groundwater ( PRZM

GW ) Fruiting vegetables, mint, ornamentals (WI sands) ( 2.0 lb a.i./A/yr: 8 apps at 0.25 lbs a.i./A, 10 day RTI ) 116.4 107.2 107.2

PROBLEM FORMULATION

This is a screening

- level drinking water assessment (DWA) that uses modeling t o estimate surface water and groundwater concentrations of pesticides in drinking water source water (pre

- treatment)

, resul ting from pesticide us e on sites that are contamination

- vulnerable. Screening

- level DWAs are designed to eliminate the need for further scrutiny of chemicals with low potential for posing a drinking water concern. This assessment is based on available

en vironmental fate data. There are no significant data gaps in the environmental fate database.

There is little existing monitoring data for tebufenozide in water or sediment , and no detections above quantitation limits

.

ANALYSIS

Use Characterization

Te bufenozide was initially registered for use on walnuts and pecans in 1994 (USEPA 1994). In February 1999, the Agency completed a screening

- level ecological risk assessment (USEPA 1999) in support of the Section 3 Registration on pome fruit, cotton, walnu ts, cole crops and leafy vegetables, sugarcane, fruiting vegetables, forests, trees, shrubs and ornamentals. Following the Section 3 registration in 1999, additional new uses resulted in risk assessments for a special local need (Section 24c) use of tebuf enozide on pasture/rangeland (D259984) in Texas4

in 1999, a Section 3 registration for use on tree nuts and almond hull s (D255779) in 1999, a Section 3 registration for use on tree nuts (D255795) in 2000, and on citrus (D270058) in 2004

. Three Inter

- region al 4 (IR

- 4) minor use registrations have been evaluated for tebufenozide on blueberries, cranberry, turnip, mint, canola and cane berries (D247304) in 1998, on sweet potatoes (D285367) in 2003, and on grapes (D285026; D285365) in 2003. Add i tionally, Secti on 18 emergency use exemptions have been granted to control lepidopterous pests on cotton in Arkansas (D216767), Texas (DP Bard D216754) and Tennessee (D216767) in 1995 ; leafy

vegeta bles in Texas (D231454) and sugarcane in Louisiana (D226011) in 1996 ; pepp ers in

Ge orgia (no DP Barcode) in 1997 ; cranberries in New Jersey (D244220)

, Washington (D243302) and Massachusetts (D245577) in 1998

- and grapes in Virginia (D274766) in 2001. A comprehensive list of currently registered tebufenozide uses, along with the ir application rates
and retreatment intervals

, is given in Table 2

.

Table 2 . Methods and r ates of a pplication of c urrently r egistered u ses of t ebufenozide

.

Use Scenario Application Type Maximum

Single Application

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

of apps/yr RTI

(days) Maximum

Annual Application

Rate (lbs a.i./A) Bushberries, Cane

berries Ground, aerial 0.25 Not specified 10 1.0

Canola Ground, aerial 0.25 Not specified 10 1.0

Citrus Ground, aerial 0.25 Not specified 14 1.25

Brassica vegetables Ground, aerial 0. 12 Not specified 10 1.8

Cotton Ground, aerial 0.25 Not specified 10 1.0 Cranberry Ground, aerial 0.25 4 7 1.0 Fruiting vegetables Ground, aerial 0.25 Not specified 10 2.0

Mint Ground, aerial 0.25 Not specified 10 2.0

Orname ntals Ground, aerial 0.25 Not specified 10 2.0

Pome fruit Ground, aerial 0.31 Not specified 10 1.875 Sugarcane Ground, aerial 0.25 Not specified 10 1.0 Almonds, Walnuts Ground, aerial 0.47 Not specified 10 1.9

Pecans Ground, aerial 0.26 Not specified 8 1.9

Other nuts Ground, aerial 0.47 Not specified 10 1.9 Trees, Forests, Shrubs Ground, aerial 0.12 Not specified 5 0.25 Pasture, rangeland Ground, aerial 0.125 4 10 0.5

Environmental Fate Characterization

Parent t ebufenozide is characterized as per sistent to very persistent 1 , with laboratory half

lives that range up to 179 days. Based upon limited data t ebufenozide’s major degradates ( RH

112651 , RH

- 112703 and RH

- 96595) appear to be somewhat less persistent than the parent, with

calculated half

- live s for summed degradates ranging from 29.3 to 123.8 days in aerobic soil studies conducted using applied parent chemical (under which conditions the decay of degradates is confounded by their simultaneous formation from the parent compound)

. Microbially

-

1 Based on the Toxic Release Inventory classification system where half

- lives greater than 60 days in water, soil, and sediment are considered persistent and half

- life greater than 6 months are considered very persistent (USEPA, 2012a)5

me diated degradation is the primary dissipation pathway for parent tebufenozide. Parent

t ebufenozide is stable to hydrolysis (pH 5

- 9) and is expected to be stable to aqueous photolysis based on its UV absorbance spectrum . The compound is also relatively st able to indirect photolysis in pond water (t 1⁄2 = 67 days) and on soil (t 1⁄2 = 98 days). No abiotic degradation data are available on any of the major degradates. In an aged soil column leaching study, the parent compound was present in four soils at approx i mately 52

- 71% of the applied after 30 days of

aerobic aging. In terrestrial field studies, parent tebufenozide dissipated with half

- lives of 39

- 53 days. Bioaccumulation studies show that the BCF for tebufenozide in fish was 151X for whole

fish tissue and showed 90% depuration within 15 days.

Tebufenozide is classified as moderately mobile based on batch equilibrium based K oc values (351

- 894 mL/g OC ) and using the Food and Agricultural Organization (FAO) soil mobility

classification scheme

. The carboxylic acid metabolite RH

- 11 2651 is classified as mobile to moderately mobile under the FAO scheme based on its K oc values ( 76

- 156 mL/g OC ) . A second carboxylic acid metabolite, RH

- 11 2703, and the ketone metabolite RH

- 9 6595, are also mobile

based on column leachi ng study results . Thus, the parent compound and all three major degradates have the potential to contaminate surface water via runoff from treated areas after application , through subsurface ( e.g ., tile drain) flow, and as a consequence of spray drift dur ing application. Tebufenozide and its degradates also have the potential to leach to groundwater. General physical/chemical properties are summarized in Table 3 and submitted environmental

fate data for tebufenozide and its major degradates are summarize d in Table 4

.

Table 3. General physical and c hemical p roperties of tebufenozide

Property Value(s) Source

Molecular weight ( g/ mol ) 352. 48 MRID 424362

- 01, 424412

- 01

Vapor pressure (Pa; at 25  C) 3 x 10

- 6 U .S. EPA, 1993

Water solubil ity (mg/L; at

25  C) 0.83 mg/L U .S. EPA, 1993

Henry’s Law Constant (atm

m 3 /mol; at 25  C) 4.0 to 5.1 x 10

- 7 U .S. EPA, 1993

Octanol

- water partition coefficient (K

ow ) 17,906 (log K

ow 4.25) U .S. EPA, 1993

Fish Bioconcentration Factor 16x (edible) 333x (nonedible)
151x (whole fish) 424362

- 09

429312

- 24

Table 4

. Environmental f ate p arameters of tebufenozide

Parameter Value (s) Source /Comments

Persistence (days)

Hydrolysis half

- lives (23

- 25  C) (d ays) stable (pH 5) stable (pH7) stable (pH 9) 424362

- 04

Aqueous photolysis half

- life (25  C) stable 424362

- 056

Parameter Value (s) Source /Comments

Soil photolysis half

- life (days; assuming 12 h light/day) ( 25  C) 98 429915

- 12

Aerobic soil metabolism half

- li v e s , parent ( 2 0  C

for CA loam and 25  C for the rest ) 153 (CA loam) 31.1 (Speyer sand) 28.2 (Speyer loamy sand) 27.8 (Speyer sandy loam) 31.4 (SLV sandy loam) 424362

- 06

487711

- 02

Aerobic soil metabolism half

- li v e s , TTR ( 20  C

for CA loam and 25  C for the rest ) 139 (CA loam) 49.7 (Speyer s and) 41.3 (Speyer loamy sand) 42.1 (Speyer sandy loam) 49.4 (SLV sandy loam) 424362

- 06

487711

- 02

Aerobic soil metabolism half

- li v e s , summed degradates (RH

- 112651 + RH

- 112703 + RH

96595 ) ( 20  C for CA loam and 25  C for the rest ) 123.8 (CA loam) 29.3 (Speye r sand) 43.7 (Speyer loamy sand) 34.6 (Speyer sandy loam) 36.3 (SLV sandy loam) 424362

- 06

487711

- 02

Aerobic aquatic metabolism half

- li v e s (days) ( 25  C) 99 (Arkansas silty clay hydrosoil) 101 (California clay loam hydrosoil) 424362

- 07

Anaerobic aquatic m etabolism half

- li v e s (days) ( 25  C) 179 429312

- 16

Mobility

S oil

- water sorption coefficients, parent (K d, mL/g) 7.8 clay

4.4 loam 1.6 loamy sand 8.2 sandy clay loam 5.7 loamy sand 424362

- 08

Organic

- carbon normalized sorption coefficients, parent (K

oc ) ( m L/g OC ) 894 clay

656 loam 351 loamy sand 391 sandy clay loam 566 loamy sand 424362

- 08

Soil

- water sorption coefficients, degradate RH

112651 (K d, mL/g) 0.68 clay 0.68 clay loam 1.54 loamy sand

0.34 sand 429312

- 19

Organic

- carbon normalized sorption coeffi cients,

d egradate RH

- 112651 (K

oc ) ( m L/g OC ) 78 clay 111 clay loam 156 loamy sand

76 sand 429312

- 19

Field Dissipation

Terrestrial field dissipation half

- li v e s (days) 39

- 53 CA sandy loam

31

- 52 NY silt loam, WA sand 4229915

- 14

437977

- 037

Drinking Water Expos ure Modeling

Models

Tebufenozid e TTR EDWCs for surface water and groundwater were generated using

EFED’s standard suite of models. The Surface Water Concentration Calculator (SWCC version

1.10 6 ; May 2014 ) model was used to generate EDWCs of tebufenozid e TTR that may occur in surface water used as drinking water. SWCC (which essentially comprises updated implementat ions of the PRZM and EXAMS models) simulates pesticide application, movement and transformation on an agricultural field and the resultant pe sticide loadings to a receiving water body via runoff, erosion, and spray drift, and then simulates the fate of the pesticide and resulting concentrations in the water body. S tandard assumptions for drinking water assessment

are a watershed of 172.8 ha th at drains into an adjacent drinking water “ index ” reservoir of 5.26

ha surface area , an d average depth 2.74 m. Spray drift (modeled as direct deposition of the pesticide into the reservoir) is assumed to be 13.5 % of the applied active ingredient for aeria l application , and 6.6% of the applied for ground application

. A Percent Cropped Area (PCA) of

100 % was used because current labels include a multi tude of agricultural uses

.
Groundwater EDWCs for tebufenozide were derived using the PRZM

- GW model (Pesticid e Root Zone Model for Groundwater, version 1.07, Nov., 2014), with the 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 vulnerable groundw ater

. The model simulates transport through the crop root zone and soil profile, of a pesticide following its application to an agricultural field. PRZM

- GW was used to simulate 30 to 100 years of repeated tebufenozide application in six standard scenario s: Delmarva, GA coastal, NC cotton, WI corn, FL potato and FL citrus. Each scenario represents a different location known to be vulnerable to contaminant leaching ( e.g ., because of sandy soils). SCI

- GROW is a regression model used as a screening tool to estimate potential pesticide concentrations in vulnerable groundwater that might be used as drinking water. SCI

- GROW was developed by fitting a linear model to groundwater concentrations with the Relative Index of Leaching Potential (RILP) as the independ ent variable. Groundwater concentrations were taken from 90

- day average high concentrations from Prospective Groundwater studies; the RILP is a function of aerobic soil

metabolism and the soil

- water partition coefficient. The output of SCI

- GROW represent s concentrations that might be expected to occur in shallow unconfined aquifers under sandy soils, which is representative of the groundwater most vulnerable to pesticide contamination likely to serve as a drinking water source

. Modeling Approach and Inp ut Parameters

Screening

- level modeling was conducted to generate EDWC s in surface water and groundwater of tebufenozide TTR following tebufenozide’s use on numerous crops and

ornamentals

. Surface water modeling for all crops was conducted using SWCC

, base d on application rates presented in Table s 2 and 6

. Input fate parameters used in surface water modeling are presented in Table 5

. Scenarios model ed with SWCC are indicated in Table 6

, along with key scenario details

. For the use on cranberries , surface water modeling was also conducted using the Provisional Cranberry Model (v 2.0, December 9, 2010) , which is a provisional refinement to the Tier I Rice Model (v1.0, May 8, 2007)

. The Provisional Cranberry Model is based on the same assumptions as the Tie r I Rice Model, with the addition of8

degradation processes in dry and flood conditions and a water depth of twelve inches in the flooded cranberry bog. The cranberry bog water depth of twelve inches is a maximum depth recommended by the Cape Cod Cranberry Growers Association (2001). Degradation of tebufenozide residues of concern is assumed to occur predominantly via aerobic microbial metabolism, whether on dry cranberry bog soil or in bog flood water. The equations used in the Provisional Cranberry Mode l are briefly describe d in Appendix B

. Input parameter values used

in groundwater modeling are presented in Table 7

. As previously mentioned

, groundwater modeling using PRZM

- GW was “refined” by simulating parent and the three summed degradates as separa te entities, then combining their resulting EDWCs to represent TTR. In conducting this modeling, application rates were adjusted to reflect the maximum percent conversion to any degradate (26.39%) noted in any of the fate studies. In terms of parent equi valents, the combined application rate of parent and degradates thus equaled the maximum label rate ( on an annual basis ) of 2.0 lb a.i./A. In running

SWCC on tebufenozide TTR

, and PRZM

- GW on the summed major degradates

, the mean soil sorption coefficient for degradate RH

- 112651 (K OC = 105 mL/ g oc ) was employ ed because it is lower (more conservative) than th e K OC of the parent . T he K OC model of sorption was determined to apply rather than the K d model because the coefficient of variation was lower for

the r eported K OC values than for corresponding K d values

. This was true both for parent
tebufenozide and for RH

- 112651. In running PRZM

- GW on parent tebufenozide

, the mean soil sorption coefficient for tebufenozide ( K OC = 566 mL/g OC ) was used. I n running SCI

- GROW on
TTR the median K OC for RH

- 112651 ( 94. 5 mL/g OC ) was used

, in accordance with EFED’s input

parameter guidance ( http://www.epa.gov/oppefed1/models/water/input_parame ter_guidance.htm ) . In running

SWCC to represent TTR , an aerobic soil metabolism half

- life of 9 3.1 days was used, which is

the 90 percent upper confidence limit on the mean value fo r five aerobic soil measurements of

half

- life of parent plus degradates RH

- 11 2651, RH

- 11 2703, and RH

- 9 6595

. In running SCI

GROW to represent TTR , an aerobic soil metabolism half

- life of 49.4 days was used

, which is

the median half

- li fe for the same aerobic soil values

.9

Table 5 . Input v alues for the SWCC m odel ing of t ebufe nozide

Input Parameter Value Source/comment

Hydrolysis half

- life (t 1⁄2 in days) 0 (stable) MRID 424362

- 04

Aqueous Photolysis half

- life (t 1⁄2 in days) 0 (stable) MRID 424362

- 05

Aerobic Soil metabolism half

- life (t 1⁄2 in days) 93.1 MRID s 424362

- 06, 478811

- 02

. Represents the 90 percent upper confidence limit on the mean of 5

aerobic soil metabolism half

- life values for parent plus degradate s RH

- 112651, RH

- 112703, and RH

96595

. 1 , 2

Aerobic Aquatic metabolism half

l ife (t 1⁄2 in days) 10 3.1 MRID 424362

- 07. Represen ts the 90 percent upper

confidence limit on the mean of two half

- life values

in aerobic silty clay soil:water and clay loam soil:water systems

.

Benthic metabolism half

- life (t 1⁄2 in days) 537 MRID 429312

- 16. Represents three times the single available w hol e

- system half

- life (179 days)

from an anaerobic silt

- loam sediment:pond water

system.
Soil partition coefficient K

oc (mL/g) 105 MRID 429312

- 19 . Mean of four K

oc values for degradate RH

- 112651.

1 EFED input parameter guidance is located at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

2 Calculation excludes NJ sandy loam soil

Table 6 . SWCC scenarios and inputs for tebufenozide modeling

Use SWC C Scenario Single Applic. Rate (lbs a.i./A) [kg/ha] Number of

Applications First Applic.

Date Bushberries, Cane

berries ORberriesOP 0.25 [0.28 ] 4 5/15

Canola NDcanolaSTD 0.25 [0.28 ] 4 5/15

Citrus FLcitrusSTD 0.25 [0.28 ] 5 5/15

Brassica FLcabbageSTD 0. 12 [0. 135 ] 15 2 /15

Cotton MScottonSTD

,

NCcottonSTD 0.25 [0.28 ] 4 5/15

Cranberry ORberriesOP 0.25 [0.28 ] 4 5/15 Fruiting vegetables FLpeppersSTD 0.25 [0.28 ] 8 5/15

Mint ORmintSTD 0.25 [0.28 ] 8 5/15

Ornamentals FLnurserySTD_V2 0.25 [0.28 ] 8 5/15

Pome fruit NCappleSTD 0.31 [ 0.347 ] 6 5/15 Sugarcane FLsugarcaneSTD

,

LAsugarcaneSTD 0.25 [0.28 ] 8 5/15

Almonds, Walnuts

, Other nuts GAPecansSTD 0.47 [ 0.527 ] 4 5/15

Pecans GAPecansSTD 0.26 [0.291] 7 5/15
Trees, Forests,

Shrubs FLnurserySTD_V2 0.12 [0. 135] 2 5/15

Pasture, rangeland RangeBSS 0.125 [0.14] 4 5/1510

Table 7 . Input values for the PRZM

- GW M odel for T ebufenozide

. Input Parameter Value Source/comment

App. Rate (lb a.i./A/yr)

, parent 1.472 (8 applications at 0.184 lb/A each) Max rate (2.0 lb/A/yr) minus max

conversion fraction to RH

- 112651 (26.39%) observed in fate studies

App. Rate (lb a.i./A/yr), RH

112651 + RH

- 112703 + RH

96595 0. 528 (8 applications at 0.066 lb/A each) Max conversion fraction to RH

112651 observed in fate studies (26.39 % in MRID 42436207 ) times max app. rate (2.0 lb/A)

Hydrolysis half

- life (t 1⁄2 in days) 0 (stable) MRID 42436204

Aerobic Soil metabolism

half

- life (t 1⁄2 in days) 92.1 (parent)

80.7 (RH

- 112651 +

RH

- 112703 + RH

- 96595 ) MRIDs 42436206, 47881102

. Represent the 90 percent upper

confidence limit on the mean of

five aerobic soil metabolism half

life values for parent and summed degradates, respectively 2

.

Soil partition coefficient K

oc (mL/g) 566 (parent)

105 ( RH

- 112651 +

RH

- 112703 + RH

- 96595 ) MRID 42436208: mea n of four values for parent

MRID 42931219 : m ean of four

values for degradate RH

- 112651

1 TTR refers to parent + RH

- 112651 + RH

- 112703 + RH

- 96595

2 EFED input parameter guidance is located at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

Table 8 . Input v alues for the SCI

- GROW m odel for t ebufenozide

Input Parameter Value Source/comment

App. Rate (lb a.i./A/yr), TTR 2

. 0 ( 0.25 lb a.i./A, 8 apps/ yr ) Label max rate (annual) for fruiting vegetables, mint and ornamentals

Hydrolysis half

- life (t 1⁄2 in days) 0 (stable) MRID 42436204

Aerobic Soil metabolism half

life (t 1⁄2 in days) 49.4 (TTR) MRIDs 42436206, 47881102 : median of

five half

- li v e s for TTR

So il partition coefficient K

oc (mL/g

oc ) 94.5 (RH

- 112651 +

RH

- 112703 + RH

- 96595) MRID 42931219 : m e di an of four values for degradate RH

- 112651

Modeling Results

S urface water EDWCs for tebufenozide TTR are presented in Table 9

. Groundwater

EDWCs are prese nted in Table 10 . V alues in bold are recommended for use in the human health dietary risk assessment. Outputs from the model runs that produced the highest EDWCs are provided in Appendix A

. Output concentrations reported in Appendix A for surface water have

not been modified for percent cropped area since the PCA adjustment factor is 1.0

, as multiple

uses are included in the DWA

. Output concentrations for groundwater are never adjusted using a PCA

, since PCAs represent watershed

- scale dilution effects t hat cannot be presumed to apply to groundwater

.11

Table 9

. Tebufenozide TTR Screening L evel EDWCs for S urface W ater 1

Use Scenario Application

Method 1

- in

- 10 year

acute (μg/L) 1

- in

- 10 year

chronic (μg/L ) 30

- year mean

cancer (μg/L)

Bushberries,

Cane berri es ORberriesOP aerial 4.00 0.396 0.316

ground 2.98 0.269 0.181

Canola NDcanolaSTD aerial 12.7 0.784 0.41 3

ground 12.3 0.707 0.327

Citrus FLcitrusSTD aerial 28.4 1.75 1.22

ground 28.7 1.72 1.16

Brassica FLcabbageSTD aerial 25.5 2.87 2.00

grou nd 26.2 2.81 1.90

Cotton MScottonSTD aerial 32.7 1.68 0.85 3

ground 32.9 1.64 0.776

NCcottonSTD aerial 27.7 1.78 1.1 3

ground 28.0 1.74 1.06

Cranberry ORberriesOP aerial 4.22 0.398 0.316

ground 3.69 0.260 0.179

Fruiting vegetables FLpeppersSTD aerial 41.8 3.13 2.19

ground 42.5 3.10 2.11

Mint ORmintSTD aerial 9.89 0.934 0.67 2

ground 9.68 0.700 0.407

Ornamentals FLnurserySTD_V2 aerial 28.5 2.27 1.62

ground 28.5 2.19 1.51

Pome fruit NCappleSTD aerial 34.1 2.88 1.50

Sugarcane FLsugarcan eSTD aerial 41.8 2.00 1.29

ground 42.5 1.99 1.26

LAsugarcaneSTD aerial 50.9 2.68 1.58

ground 51.8 2.68 1.54

Almonds,

Walnuts

, Other

nuts GAPecansSTD aerial 43.0 2.17 1.3 2

ground 42.3 2.03 1.14

Pecans GAPecansSTD aerial 27.3 1.88 1.2 2

ground 27.2 1.70 1.03

Trees, Forests,

Shrubs FLnurserySTD_V2 aerial 1 0

. 8 0.438 0.2 04

ground 10.7 0.432 0.190

Pasture, rangeland RangeBSS aerial 19.2 1.13 0.60 8

ground 19.4 1.14 0.583

Cranberry Provisional

Cranberry Model 2 NA 279.3 105.8 105.8 3

1 Bolded value s are the highest surface water concentrations.

2 Not a SWCC scenario

3 Reflects a 21

- day holding time, post

- flood.12

Table 10

. PRZM

- GW and SCI

- GROW groundwater EDWCs based on tebufenozide use on fruiting vegetables, mint and ornamentals.

PRZM

- GW R esults

Scenario Simulated

Chemical Entity Annual

Appl. Rate (lbs a.i./A) 1 Max. Daily

Conc. (μg/L) Post

Breakthrough

Mean Conc. (μg/L) Simulation

Breakthrough Time (days)

Delmarva T ebufenozide 1.472 9.79 8.85 7967

Major degs 0.528 34.6 31.4 2359

TTR 2.0 44.4 40.2 NA FL (citrus) Tebufenozide 1.472 23.7 22.4 6473

Major degs 0.528 50.8 43.2 1772

TTR 2.0 74.5 65.6 NA

FL (potato) Tebufenozide 1.472 0.0041 0.0026 13058

Major degs 0.528 2.59 1.59 2834

TTR 2.0 2.59 1.59 NA

GA (coastal) Tebufenozide 1.472 3.31 2.99 10667

Major degs 0.528 16.0 14.8 2954

TTR 2.0 19.3 17.8 NA

NC (coastal) Tebufenozide 1.472 5.09 4.8 7245

Major degs 0.528 35.9 29.7 2924

TTR 2.0 41.0 34.5 NA WI (corn) Tebufenozide 1.472 40.4 38.1 10027

Major degs 0.528 76 69.1 3777

TTR 2.0 116.4 2 107.2 2 NA

SCI

- GROW Results Simulated Chemical Entity Application Rate EDWC (μg/L)

TTR 0.25 lb a.i./A, 8 apps/yr 1.18

1 Of parent equivalents.

2 Bolded values are recommended for use in the human health dietary risk assessment

The PRZM

- GW and SCI

- GROW results represent groundwater concentration s that might be expected in shallow

, unconfi ned aquifers under sandy soils. The SWCC model result s represent concentrations that might occur in untreate d surface water in runoff

- vulnerable

l ocations. The simulated concentrations provided in this assessment are expected to represent conservative estimates of concentrations in drinking water.

Monitoring Data

Only limited m onitoring data are available for tebufenozide

. EFED conducted a sear ch (January 27, 2015) of the USGS National Water Quality Assessment ( NAWQA ) Program

database ( http://cida.usgs.gov/nawqa_queries_public/ ) , the USGS Community Water S ystem ( CWS ) data (http://pubs.usgs.gov/ds/544/) , the CDPR surface water and sediment databa se (http://cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm) , and the USEPA /USGS / NWQMC (National Water Quality Monitoring Council) Water Quality Portal database ( http://www.waterqualitydata.us/ ) . The CWS

, CDPR and Water Quality Portal databases d o not
include a ny records of tebufenozide as a sampled constituent. The NAWQA database lists

tebufenozide as a constituent, and includes records of 11 “ filtered ” samples collected from the

Rio Grande River , near Browns ville, TX, on various dates in 20 13

. All result s ar e listed as “< 2

n g/L” , which presumably re flec t s the analytical method limit of quantitation

.13

Drinking Water Treatment Effects

N o specific information on the effects of drinking water treatment on the removal of

tebufenozide or its degradates is curr ently available. The EDWCs in this assessment are representative of concentrations in drinking water source water (pre

- treatment) and are derived from daily instantaneous peak concentrations. For surface water, the conceptual model assumes that pesticide reaches surface water via spray drift and runoff, and is then instantaneously mixed

within the water column and reversibly sorbed to benthic sediments

. As tebufenozide residues

are stable to hydrolysis and appear to be stable to abiotic oxidation

, the co mpound is not expected to degrade during the time that elapses from drinking water intake through distribution

to the consumer’s tap. Because organic carbon mediates the sorption of tebufenozide to soils

, treatment methods such as sedimentation, flocculat ion, and activated carbon, that are designed to capture contaminants via sorption, may remov e some tebufenozide and/ or its degradates

. Tebufenozide does not degrade via aqueous photolysis ; therefore

, w here ultraviolet light is used

as a means of disinfect ion, degradation is not expected to be enhanced

. Uncertainties and Data Gaps

This assessment is based on available environmental fate data. There are no significant data gaps in the environmental fate database submitted by the registrant. The drinking water assessment is a screening

- level assessment based on simpl e models and assumptions. The modeling assessment relies on maximum use patterns and national default PCAs to reflect potential surface and groundwater concentrations. To the extent that actu al use patterns involve application of less a.i. than the permissible (labeled) maxima, aquatic concentrations could be

lower than EDWCs reported herein

.

C ITATION S

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

S heet. June, 2001. Online at: http://www.cranberries.org/pdf/wateruse.pdf

. Accessed Mar. 17, 2010.

Dhadialla, T. S. , G. R. Carlson, and D. P. Le. 1998. New insecticides w ith ecdysteroidal and juvenile hormone activity. Annual Reviews in Entomology 43: 545

- 569.

Shimizu, B., Y. Nakagawa, K. Hattori, K. Nishimura, N. Kurihara, and T. Ueno. 1997. Molting hormonal and larvicidal activities of aliphatic acyl analogs of dibenzoylhydrazine insecticides. Steroids 62 (10): 638

- 642.

U.S. Environmental Protection Agency. 1993. Review of data to support EUP use in forests

. February 8 , 1993 (DP Barcode D182683).

U.S. Environmental Protection Agency

. 1994. EEB Branch Review Section 3 Registration of Tebufenozide Use on Walnuts (Scan Bar Code 2072743)

.

U.S. Environmental Protection Agency. 1999

. EFED risk assessment for Section 3 registration of tebufenozide (Confirm TM 2F & 70WSP). February 26, 1999 (DP Barcode D232998).14

U.S. Environmental Protection Agency. 2008. Registration Review

– Preliminary Problem Formulation for Ecological Risk and Environmental Fate, Endangered Species, and Drinking Wat er Assessments for Tebufenozide

. Office of Pesticide Programs.

Environmental Fate and Effects Division. 4 November 2008. DP Barcode s D352989, D352987, D352988

. U.S. Environmental Protection Agency. 2009. Guidance for Selecting Input Parameters in

Model ing the Environmental Fate and Transport of Pesticides, Version 2.1. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division, October 22, 2009. Onli ne at: http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

U.S. Environmental Protection Agency. 2012. Criteria Used by the PBT Profiler. September 4 , 2012. Office of Chemical Safety and Pollution Prevention. United States Environmental Protection Agency. Available at http://www.pbtprofiler.net/criteria.asp (Accessed January 23, 2015 )

U.S. Enviro nmental Protection Agency. 2012. Guidance for Selecting Input Parameters for Modeling Pesticide Concentrations in Groundwater Using the Pesticide Root Zone Model, Version 1.0. U.S. Environmental Protection Agency

, Office of Pesticide Programs

, Environm en tal Fate and Effects Division. H ealth Canada

, Pesticide Management Regulatory Agency

, Environmental Assessment Directorate . October 15,

2012.

U.S. Environmental Protection Agency. 2014. Tebufenozide: Residues of Concern in Drinking

Water. Memo from Mohs en Sahafayen to Jim Carleton and Sarah Winfield. Office of Pesticide Programs

, Health Effects Division. DP Barcode 423156

.15 

### Appendix A

SELECTED SURFACE WATER AND GROUNDWATER MODELING

OUTPUT FILES

SWCC Output

Summary of Water Modelin g of tebufenozide TTR (sugarcane) and the

USEPA Standard Reservoir

Estimated Environmental Concentrations for tebufenozide are presented in Table 1 for the USEPA standard reservoir with the LAsugarcaneSTD field scenario. A graphical presentation of the yea r

- to

- year peaks is presented in Figure 1. These values were generated with the Surface Water Calculator (Version 1.101). Critical input values for the model are summarized in Table 2.

This model estimates that about 3.4% of tebufenozide TTR applied to the field eventually reaches the water body. The main mechanism of transport from the field to the water body is by runoff (91% of the total transport), followed by spray drift (5.9%), and erosion (2.9%).

In the water body, pesticide dissipates with an effecti ve water column half life of 8.6 days. (This value does not include dissipation by transport to the benthic region; it includes only processes that result in removal of pesticide from the complete system.) The main source of dissipation in

the water column is volatilization (effective average half life = 12.1 days), followed by washout (37.9 days), and metabolism (139.6 days).

In the benthic region, pesticide dissipates very slowly (727.2 days).The main source of dissipation in the benthic region is metabol ism (effective average half life = 727.2 days). The vast majority of the pesticide in the benthic region (91.9%) is sorbed to sediment rather than in the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for tebufenozide TTR

. Peak (1

- in

- 10 yr) 51.8

4

- day Avg (1

- in

- 10 yr) 43.8

21

- day Avg (1

- in

- 10 yr) 28.7

60

- day Avg (1

- in

- 10 yr) 14.8

365

- day Avg (1

- in

- 10 yr) 2.68

Entire Simulation Mean 1.54

Table 2. Summary of Model Inputs for tebufenozide.

Scenario LAsugarcaneSTD

Koc (ml/g) 105

Wat er Half Life (days) @ 25 °C 103.116

Benthic Half Life (days) @ 25 °C 537

Photolysis Half Life (days) @ 40

°Lat 0

Hydrolysis Half Life (days) 0

Soil Half Life (days) @ 25 °C 93.1

Foliar Half Life (days) 0

Molecular Wt 352

Vapor Pressure (torr) 2.25e

- 4

Solubility (mg/l) .83

Figure 1. Yearly Peak Concentrations17



### Summary of Water Modeling of tebufenozide TTR (fruiting vegetables) and

the USEPA Standard Reservoir

Estimated Environmental Concentrations for tebufenozide are presented in Tab le 1 for the USEPA standard reservoir with the FLpeppersSTD field scenario. A graphical presentation of the year

- to

- year peaks is presented in Figure 1. These values were generated with the Surface Water Concentration Calculator (SWCC Version 1.106). Criti cal input values for the model are

summarized in Tables 2 and 3.

This model estimates that about 2.9% of tebufenozide applied to the field eventually reaches the water body. The main mechanism of transport from the field to the water body is by runoff (85. 6% of the total transport), followed by spray drift (14.3%) and erosion (0.07%).

In the water body, pesticide dissipates with an effective water column half

- life of 6.6 days. (This value does not include dissipation by transport to the benthic region; it i ncludes only processes that result in removal of pesticide from the complete system.) The main source of dissipation in the water column is volatilization (effective average half

- life = 8.6 days) followed by washout (37.9 days) and metabolism (112.9 days).

In the benthic region, pesticide dissipates slowly (192.5 days). The main source of dissipation in the benthic region is metabolism (effective average half

- life = 192.5 days). The vast majority of the pesticide in the benthic region (91.9%) is sorbed to s ediment rather than in the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for tebufenozide TTR

. Peak (1

- in

- 10 yr) 41.8

4

- day Avg (1

- in

- 10 yr) 36.1

21

- day Avg (1

- in

- 10 yr) 21.2

60

- day Avg (1

- in

- 10 yr) 12.0

365

- day Avg (1

- in

- 10 yr) 3. 13

Entire Simulation Mean 2.19

Table 2. Summary of Model Inputs for tebufenozide TTR

.
Scenario FLpeppersSTD

Cropped Area Fraction 1.0

Koc (ml/g) 105

Water Half

- Life (days) @ 25 °C 105

Benthic Half

- Life (days) @ 25 °C 179

Photolysis Half

- Life (days) @ 40

°Lat 0

Hydrolysis Half

- Life (days) 018

Soil Half

- Life (days) @ 25 °C 93.1

Foliar Half

- Life (days) 0

Molecular Wt 352

Vapor Pressure (torr) 2.25e

- 4

Solubility (mg/l) .83

Table 3. Application Schedule for tebufenozide.

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

5/15 Foliar 0.28 .95 .135

5/25 Foliar 0.28 .95 .135

6/4 Foliar 0.28 .95 .135

6/14 Foliar 0.28 .95 .135

7/15 Foliar 0.28 .95 .135

7/25 Foliar 0.28 .95 .135

8/4 Foliar 0.28 .95 .135

8/14 Foliar 0.28 .95 .135

Figure 1. Yearly Peak Concentrations19



### PRZM

- GW Output

Groundwater Analysis for tebufenozide (parent) and the Wisconsin Corn

- WI Central Sands Scenario

Estimated groundwater concentrations and breakthrough times for tebufenozide are presented in

Table 1 for the Wisconsi n Corn

- WI Central Sands groundwater scenario. A graphical presentation of the daily concentrations in the aquifer is presented in Figure 1. These values were generated with the PRZM

- GW (Version 1.07). Critical input values for the model are

summarized in Tables 2 and 3.

Table 1. Groundwater Results for tebufenozide and the Wisconsin Corn

- WI Central

Sands Scenario.

Peak Concentration (ppb) 40.4

Post

- Breakthrough Mean Concentration (ppb) 38.1

Entire Simulation Mean Concentration (ppb) 29.1

Average Breakthrough Time (days) 10026.81

Throughputs 3.606532

Table 2. Chemical Properties for Groundwater Modeling of tebufenozide.

Koc (ml/g) 572

Surface Soil Half Life (days) 92.1

Hydrolysis Half Life (days) 0

Diffusion Coefficint Air (cm2/day) 0

Henry's Constant 0.0

Enthalpy (kcal/mol) 0.0

Table 3. Pesticide application scheme used for tebufenozide. This application scheme was applied every year of the simulation.

Application Date

(Month/Day) Application Method Application Rate

(kg/ha)

5/1 5 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.20620

5/25 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.206

6/4 Ground application with mass

distribution increasing

prop ortionally with depth to 4 cm 0.206

6/14 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.206

6/24 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.206

7/4 Ground applicatio n with mass

distribution increasing proportionally with depth to 4 cm 0.206

7/14 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.206

7/24 Ground application with mass

distribution increasing proportionally with de pth to 4 cm 0.206

Figure 1. Aquifer Breakthrough Curve for tebufenozide and the Wisconsin Corn

- WI

Central Sands Scenario21



### Groundwater Analysis for tebufenozide degradates (RH

- 112651 + RH

- 112703

+ RH

- 96595) and the Wisconsin Corn

- WI Central Sands Scenario

Estimated groundwater concentrations and breakthrough times for tebufenozide degradates are presented in Table 1 for the Wisconsin Corn

- WI Central Sands groundwater scenario. A graphical presentation of the daily concentrations in the aquifer i s presented in Figure 1. These values were generated with the PRZM

- GW (Version 1.07). Critical input values for the model

are summarized in Tables 2 and 3.

Table 1. Groundwater Results for tebufenozide degradates and the Wisconsin Corn

- WI

Central Sands Scenario.

Peak Concentration (ppb) 76

Post

- Breakthrough Mean Concentration (ppb) 69.1

Entire Simulation Mean Concentration (ppb) 46.7

Average Breakthrough Time (days) 3777.435

Throughputs 2.90144

Table 2. Chemical Properties for Groundw ater Modeling of tebufenozide degradates

. Koc (ml/g) 105

Surface Soil Half Life (days) 80.7

Hydrolysis Half Life (days) 0

Diffusion Coefficint Air (cm2/day) 0

Henry's Constant 0.0

Enthalpy (kcal/mol) 0.0

Table 3. Pesticide application scheme used fo r tebufenozide degradates . This application scheme was applied every year of the simulation.

Application Date

(Month/Day) Application Method Application Rate

(kg/ha)

5/15 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.074

5/25 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.07422

6/4 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.074

6/14 Ground application with mass

distribution i ncreasing proportionally with depth to 4 cm 0.074

6/24 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.074

7/4 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.074

7/14 Gro und application with mass

distribution increasing proportionally with depth to 4 cm 0.074

7/24 Ground application with mass

distribution increasing proportionally with depth to 4 cm 0.074

Figure 1. Aquifer Breakthrough Curve for tebufenozide degradates and the Wisconsin

Corn

- WI Central Sands Scenario23

SCIGROW Output

SCIGROW

VERSION 2.3

ENVIRONMENTAL FATE AND EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS

U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL

FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

chemical:tebufenozide TTR time is 2/ 3/2015 8:41:44

--------------------------------------------- --------------------------- Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 0.25 0 8.0 2.000 9.45E+01 49.4

------------------------------------------------------------------------ groundwater screening cond (ppb) = 1.18E+00

************************************************************************24 

### Appendix B PROVISIONAL CRANBERRY MODEL EQUATIONS

The Provisional Cranberry Model is a refinement of the Tier I Rice Model v1.0 (Equation s 1 and 2 ) , which is a simple equilibrium partitioning equation that calculates a single,

scre ening

- level concentration in rice paddy water and released tailwater based on a compound’s applic ation rate and soil mobility.

Equation s 1

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

(1)

and, if appropriate:

(2)

where,

C
w 0 = initial water concentration [μg/L]

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

K d = water

- sediment partitioning coefficient [L/kg]

K OC = organic carbon partitioning coefficient [L/kg]

d

w = water column depth = 0.10 m

d sed = sediment dep th = 0.01 m

θ sed = porosity of sediment = 0.509

ρ b = bulk density of sediment = 1300 kg/m 3

First, t he Tier I Rice Model was pr ovisionally modified (Equation 3 ) to include as inputs degradation rate constants in or der to estimate single, screening

- level concentration s in paddy

water or tailwater at a given time after application.

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

(3)

where,

C
w = water concentration [μg/L] t = interval since last application [ d ] k = upper 90 th perce ntile degradation rate constant [ 1/d ]25



### Then, the Provisional Modified Rice Model water column depth was

increas ed to a depth that is used to flood cranberry bogs ( i.e. , 12 inches; Cape Cod
Cranberry Growers Association, 2001 

### ).

i.e.

, d

w = water column dep th = 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 i n a Dry Bog.

(4)

where,

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

m ai '
n = mass applied per unit area on the n th application [kg/ha]

k 2 = upper 90 th percentile degradation rate constant on dry bog [ 1/d ]

t n = interval from the n th application to harvest [ d ]

n = number of pre

- harvest applications



### These four equations and parameter sets constitute the Provisional Cranberry Model (Equations 1

- 4).

Equations 2, 4

, and 5 : Provisional Cranberry Model.

(4)

whe re,

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

m ai '
n = mass applied per unit area on the n th application [kg/ha]

k 2 = upper 90 th percentile degradation rate constant on dry bog [1/d]

t n = interval from the n th application to harvest [d] n = number of pre

- h arvest applications

followed by:

( 5 )26 and, if appropriate:

(2)

where,

C
w = water concentration [μg/L] t = interval since flood [d] k = upper 90 th percentile degradation rate constant [1/d]

K d = water

- sed iment partitioning coefficient [L/kg]

K OC = organic carbon partitioning coefficient [L/kg]

d

w = water column depth = 0.305 m

d sed = sediment depth = 0.01 m

θ sed = porosity of sediment = 0.509

ρ b = bulk density of sediment = 1300 kg/m 3