UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

DP Barcodes: 0423653 and 423655 

PC Code: 056008 

MEMORANDUM 

DATE: June 24, 2015 

SUBJECT: Application for Registration of New Use of Ethyl I- Naphthaleneacetate, on 

Pomegranate in Association with IR-4 petition 4E83 l 0 for the Product Tre-hold 

Sprout Inhibitor A 112. 

TO: Driss Benmhend, Risk Manager Reviewer 

Shaja Joyner, Risk Manager #20 

FROM: 

Cynthia Giles-Parker, Chief 

Fungicide Branch 

Laura Nollen, Risk Manager Reviewer 

Barbara Madden, Risk Manager, Risk Manager #05 

Luis Suguiyama, Acting Chief 

Risk Integration, Minor Use and Emergency Re~ponse Branch 

Registration Division (7505P) ,,.. k4.-

Jose L. Melendez, Chemist ~ .._ l' f4e:u!:41.:A.~ Brian 

Allen 

Montague

Vaughan, 

, 

Ri

Fishery 

sk Assessment 

Biologist

Proce

~ 

ss Leader 

Environmental Risk Branch V 

Environmental Fate and Effects Division (7507P) 

THROUGH: Mah T. Shamim, Ph.D., Chief 

Environmental Risk Branch V 

~~ 

Environmental Fate and Effects Division (7507P) 

The Environmental Fate and Effects Division (EFED) has reviewed the proposed new use for the 

ethyl I -naphthalene acetate (NAA-EE) on pomegranate for trunk sprout and root sucker control. 

The Interregional Research Project No. 4 (IR-4). and the regist~ant, AMV AC Chemical 
2

Corporation, petitioned a tolerance exemption for the above mentioned crop for the product TreHold® Sprout Inhibitor A-112. The product would be applied as a spray in a 1% active solution 

at up to 44 gallons per acre. 

Pomegranates are generally grown in the arid climates of California and a small area of Arizona. 

They are adaptable to a wide range of soils such as deep loam, sandy soils and adobe clay soils. 

Generally, between 150 -200 trees are planted per acre with 18 feet between rows and 12 to 18 

feet between trees. Acreage has been increasing with 35,000 acres planted in California in 2013, 

up from 15,000 acres 6 years earlier. (Western Farm Press May 2013).

EFED evaluated the proposed new use against the previous assessment of the uses for the 

chemical. A previous assessment for the use of the chemical on avocado (D361448) concluded 

that the proposed use of two applications at 0.22 lb a.e./A (a.e. means acid equivalent) at 45 day 

intervals should not pose acute or chronic risk to any non-target organisms. However, the new 

proposed use is at a much higher rate and, as a result, EFED has reassessed potential exposure 

levels. Table 1 shows a summary of application information proposed for pomegranate along 

with label application information for other registered crops.

Table 1. Summary use information for naphthalene acetates, based on the 2007 revision of the RED 

(USEPA 2007), the sample labels for Rejuvenate Seed Treatment1, Fruitone® L2, and the proposed label 

for Tre-Hold® Sprout Inhibitor A-1123. The proposed new use is in bold type.

USE

SINGLE 

APP. 

RATE

(lb. a.e./A)*

NO.

APPS AT 

MAX 

RATE

SEASONAL 

APP. RATE 

(lb. a.e./A)

INTERVAL 

BETWEEN 

APPS. 

(days)

APP.

METHOD

*

INCORP. 

DEPTH 

(inches)

Pomegranate 3.6 2 7.2 60 Spray** 0

Avocado, mamey sapote, mango 0.11 2 0.22 45 G, A, B 0

CG 11–10: Pome fruits: apple, 

pears, azarole, crabapple, loquat, 

mayhaw, medlar, Asian pear, 

quince, Chinese quince, Japanese 

quince, Japanese quince, tejocote 

and cultivars, varieties and/or 

hybrids of these

0.11 3 0.33 5 G, A, SD 0

Citrus (mandarin, oranges, 

tangelos, tangerines, and nonbearing), cherries, some nonbearing fruit and nut trees, 

ornamental plants (herbaceous, 

non-flowering trees, woody shrubs 

and vines), shade trees, and 

residential fruit, and ornamental 

trees

0.11 3 0.33 5 G, A, SD 0

Olives 0.33 1 0.33 N/A AB 0

 1 Rejuvenate Seed Treatment (EPA Reg. No. 87320-2) contains 6.25% NAA potassium salt or 0.44 lb NAA 

a.e./gallon.

2 Fruitone L® (EPA Reg. No. 5481-541) contains 3.5% NAA sodium salt or 3.1% NAA a.e. 3 Tre-Hold® Sprout Inhibitor A-112 (EPA Reg. No. 5481-429) contains 15.1% NAA ethyl ester or 1 lb NAA 

a.e./gallon.
3

Table 1. Summary use information for naphthalene acetates, based on the 2007 revision of the RED 

(USEPA 2007), the sample labels for Rejuvenate Seed Treatment1, Fruitone® L2, and the proposed label 

for Tre-Hold® Sprout Inhibitor A-1123. The proposed new use is in bold type.

USE

SINGLE 

APP. 

RATE

(lb. a.e./A)*

NO.

APPS AT 

MAX 

RATE

SEASONAL 

APP. RATE 

(lb. a.e./A)

INTERVAL 

BETWEEN 

APPS. 

(days)

APP.

METHOD

*

INCORP. 

DEPTH 

(inches)

Potato seed pieces 0.0004 1 0.0004 N/A ST 3***

*a.e. = acid equivalents; N/A = not applicable; G = ground; A = aerial; SD = dip or soil drench; ST = seed treatment; AB = 

airblast; B = brush, sponge or paint roller (to individual trees); T = treat rambutan panicles spraying solution to runoff.

**Ground applications, diluted in a large volume of water, applied to the lower tree trunks and immediate surrounding area. 

The PHI is 45 days.

***Shallowest depth of planting potatoes was obtained from the following source, accessed 08/27/2012: 

http://www.cals.uidaho.edu/potatoes/Research&Extension/Topic/Seed&Planting/EffectsOfRemovingSeedPieces&PlantingDe

pthOnPotatoYield-99.pdf (William H. Bohl and Stephen L. Love. 1999. Affects of Removing Seed Pieces and Planting Depth 

on Potato Yield). Furthermore, the following site states that, “Generally the center of the seed piece should be planted 2 to 4 

inches below field level and covered with 2 to 3 inches of soil.” (The site was accessed 08/27/2012: 

http://www.ag.ndsu.edu/pubs/plantsci/rowcrops/ae1040w.htm.)

##Even though the label is not clear on what is the application rate per acre, it appears to 0.11 lb a.e./A, similar to other crops.

Aquatic Organism Exposure and Risk Quotients (see previous Problem Formulation 

D421702, USEPA 2014, for toxicity values used in this assessment)

Preliminary evaluation indicated that using EECs from the Tier 1 model GENEEC2 would yield 

RQs that exceed the levels of concern for some taxa; therefore, EFED proceeded with Tier 2 

modeling using the SWCC (Surface Water Concentration Calculator). The results of GENEEC2 

are summarized in Appendix A and not discussed further here. Table 2 shows the EECs 

obtained from the Tier 2 SWCC model. For the input parameters used in the models, and model 

output files, refer to the Appendices A and B, respectively.

Table 2. NAA EE Surface Water EECs Based on the SWCC Tier 2

Peak (mg/L) 21-day (mg/L) 60-day (mg/L)

0.00839 0.00328 0.00131

Pore Water Peak (mg/L) Pore Water 21-day (mg/L)

0.00103 0.000995

Risk quotients in Table 3 are based on SWCC exposure estimates and toxicity values from actual 

submitted study results or ECOSAR estimates for toxicity to aquatic organisms where data has 

not been submitted. Based on these risk quotients no acute or chronic Levels of Concern are 

exceeded for the proposed Pomegranate use for trunk sprout and root sucker control.

Table 3. Risk Quotients for Aquatic Species Based on the Tier 2 SWCC and NAA, EE Endpoints

Species Endpoint Toxicity Value 

(mg/L) RQ

Fish, Acute Exposure

Actual Value Bluegill sunfish-(MRID 42498101) 96-hr, LC50 2.68 <0.01

Fish, Chronic Exposure

Estimated value using ECOSAR 1.11 Chronic Value 0.14 0.01
4

Table 3. Risk Quotients for Aquatic Species Based on the Tier 2 SWCC and NAA, EE Endpoints

Species Endpoint Toxicity Value 

(mg/L) RQ

Aquatic Invertebrates, Acute Exposure

15.1 % Formulation Test EC50 corrected to 100%-

Daphnia magna (MRID 00042755) 48-hr, LC50 3.6 <0.01

Aquatic Invertebrates, Chronic Exposure

Estimated value using ECOSAR 1.11 -Daphnia magna ChV (esters) 1.95 0.02

Estimated value using ECOSAR 1.11 -Daphnia magna ChV (neutral orgs) 0.49 0.01

Marine/Estuarine Aquatic Invertebrates, Acute

Estimated value using ECOSAR 1.11 - Mysid Shrimp 96-hr, LC50 1.55 0.01

Marine/Estuarine Aquatic Invertebrates, Chronic

Estimated value using ECOSAR 1.11 -Mysid Shrimp Chronic Value 3.24 <0.01

Aquatic Plants, Acute Exposure

Estimated value using ECOSAR 1.11 Green Algae 96-hr, EC50 1.52 0.01

Aquatic Plants

Estimated value using ECOSAR 1.11 Green Algae Chronic NOEC 0.69 0.01(1)

(1) It is a chronic endpoint. However, compared against the peak EEC the RQ is less than 1.0.

Terrestrial Organism Toxicity and Exposure Considerations

NAA EE has been observed to be practically non-toxic to birds on an acute dietary basis. The 

observed dietary value for Bobwhite quail with NAA ethyl ester technical exceeded 5620 ppm 

(MRID 42584202) with no mortality or adverse effects observed at this level. Acute toxicity to 

laboratory mammal was observed to be 2186 mg a.i./Kg of body weight (practically non-toxic) for 

the technical grade NAA ethyl ester. No avian oral acute or chronic avian reproduction studies 

are available for NAA ethyl ester, though the NAA salt was observed to be slightly toxic to mallard 

duck on an oral basis (LD50 1750 mg a.i./Kg bw). At higher rates for pomegranate use (3.6 lb 

ai/A) predicted residue levels for exposed short grasses immediately surrounding Pomegranate 

trees could reach 450 ppm for typical and 864 ppm for maximum residue levels as acid equivalent

values. Though an actual LC50 has not been established acute hazard to birds is not predicted 

from this use. 

Chronic avian reproduction data for a similarly structured compound with the same mode of action 

(quinclorac; NOAEC = 500 - 1000 ppm; MRID 44084501 & 44129201), in addition to that for 

other synthetic auxins (aminopyralid, dicamba; NOAEC = 800-2600 ppm), suggest low chronic 

toxicity to birds. However, areas immediately surrounding the bases of treated Pomegranate trees 

could reach residue levels within this range of chronic toxicity values if maximum expected 

residue values on short grass are assumed. Typical expected residue levels would not exceed the 

Chronic NOAEL observed for similar chemicals.

Acute toxicity to honeybees has not been determined for the ethyl ester or other NAA salts (data 

has been requested for the Napthalene acetic acid). However, the exposure of pollinator insects to 

trunks of sprayed pomegranates following targeted application would be unlikely. 
5

Currently the Agency has no terrestrial plant data for NAA ethyl ester and only a few studies with 

an NAA salt formulations Drift of spray to surrounding vegetation and non-target plants is 

possible, but the targeted application to sprouts or cuttings would appear to limit this type of 

exposure pathway. Label precautions regarding the prevention of spray drift are included. Runoff 

to adjacent areas would be based on residues concentrated immediately near the root structures of 

pomegranate trees and not in the row areas between trees. 

Uncertainties

Very little environmental fate data were available for these compounds. Quantitative structure 

activity relationships (QSAR) and limited available data were used to derive some of the input 

parameters for the models. The major uncertainties with respect to this assessment are related to 

the absence of measured values for fate parameters. Furthermore, there is lack of information 

about possible degradates of NAA.

No toxicological data is available to the Agency regarding chronic effects for aquatic 

invertebrates, fish or terrestrial wildlife with NAA-EE or the NAA acid form. In addition, no 

pollinator insect data has been submitted, though for direct application to trunks or cuttings this 

is not determined to be an exposure concern. Runoff to non-target terrestrial plants near 

pomegranate orchards is potentially possible, but with no actual NAA-EE or NAA plant toxicity 

data on this formulation or half-life data in soils, characterization of the potential risk to nontarget plants cannot be made with any certainty.

Environmental Fate and Ecological Effects data have been requested in the Registration Review 

Problem formulation for NAA actives that would help to alleviate these uncertainties (see 

D423581 dated November 18, 2014 for further details).

EFED Label Recommendations

The following label statements are recommended based in part on the OPP Label Review 

Manual (Chapter 8, 09/2012), available at http://www.epa.gov/oppfead1/labeling/lrm/index.htm

(accessed 10/11/2012).

i. End-Use Product Environmental Hazards

EFED notes that the following statements already appear in the proposed label:

“Do not apply directly to water, to areas where surface water is present, or to intertidal areas 

below the mean high water mark. Do not contaminate water by cleaning of equipment or 

disposal of wastes. Do not contaminate irrigation ditches or water used for irrigation or domestic 

purposes. Do not apply when conditions favor drift from treated areas. Do not use in a 

greenhouse. Do not store near extreme heat, open flame, or sources of ignition.”
6

EFED suggests replacing the sentence, “Do not contaminate water by cleaning of equipment or 

disposal of wastes.” with “Do not contaminate water when disposing of equipment washwater or 

rinsate.” The recommended sentence complies with the current Label Review Manual.

ii. Label Statement for Spray Drift Management

EFED notes that the following statements already appear in the proposed label:

Tre-Hold® Sprout Inhibitor A-112 Label:

SPRAY DRIFT MANAGEMENT: A variety of factors including weather conditions (e.g., wind 

direction, wind speed, temperature, relative humidity) and method of application can influence 

pesticide drift. The applicator and grower must evaluate all factors and make appropriate 

adjustments when applying this product. Do not apply by spray when wind speeds are greater 

than 10 mph at the application site. Use only medium or coarse spray nozzles or droplets.

.

Risk Characterization and Conclusions

Based on SWCC Tier II modeling for Pomegranate uses at a maximum of 3.6 lbs ai/acre and 2 

applications, no aquatic species levels of concern are exceeded. Predicted environmental 

concentration are far below any observed or predicted toxicity levels for fish, invertebrates or 

aquatic plants. It should be noted that this conclusion is based on a very limited data set and 

extensive chemical structure modeling estimation for missing toxicological endpoints. 

Tre-Hold A112 is applied as a directed spray to lower tree trunks and immediate surrounding 

root growth areas for control of sprouts and root suckers. The radius of this concentrated spray 

area is not clearly defined on the label, but it is anticipated that residue levels immediately 

surrounding the trees could be higher than would be expected from this spray concentration if 

distributed over an entire acre. There is some uncertainty as to what exposure levels would be 

expected under current label directions and therefore some uncertainty as to what levels of NAA 

EE wildlife could be exposed to. Acute toxicity to birds and mammals is low and acute risk is 

not expected even with concentrated areas under trees. The levels that would indicate chronic 

risk to birds are reached if predictions for chronic toxicity are based on similar structured 

chemicals such as Quinclorac (NOAEL=500 ppm/LOAEL = 1000 ppm). 

As no honeybee toxicity data has been submitted for NAA salts or the ester there is some 

uncertainty regarding potential risk. The AMVAC has indicated that data are available in Europe 

and that results indicate low toxicity to honeybees. EFED does expect that direct application to 

trunk sprouts or root suckers will provide very limited exposure potential to pollinator insects. 

Therefore risk to these beneficial pollinators is not expected.

Seedling emergence effects to sensitive dicot terrestrial crop plant were observed at 0.011- 0.015 

lb ai/A with ammonium salt formulation. The monocot species showed less sensitivity to this 

formulation. With the potassium salt formulation effects to vegetative vigor were observed at 
7

0.01 to 0.043 lb ai/A for dicots and effects to monocots were observed at 0.02-0.075 lb ai/A. 

However, EFED does not expect direct application to tree trunks and root structure to lead to 

significant off target plant exposure with proper spray drift precautions. Hot arid areas in which 

pomegranates are grown would offer less potential for runoff events as well. Effects to nontarget crops or vegetation is not expected from this usage as proposed on the current label.

References

Crosby, D.G., Tang, C.S. 1969. Photodecomposition of 1-Naphthaleneacetic Acid. 17(6), 1291-

1293.

USEPA 2007. Reregistration Eligibility Decision (RED) Naphthaleneacetic Acid, Its Salts, Ester, 

and Acetamide. OCSPP. OPP. EPA 738-R-07-07017. Revised October 2007.

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

Transport of Pesticides, Version 2.1 (dated October 22, 2009 and approved November 10, 

2009), available at 

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

04/08/2015).

USEPA 2014. Problem Formulation for Registration Review of Napthaleneacetic Acid and Its 

Sodium, Potassium and Ammonium Salts, Ethyl Ester and Acetamide (Document ID 

EPA‐HQ‐OPP‐2014‐0773-0003 in www.regulations.gov, DP Barcode: D423581, dated 

November 18, 2014).
8

Appendix A. Aquatic Modeling for NAA EE

Tier 1 Modeling Using GENEEC2

GENEEC was designed to mimic a much more sophisticated PRZM/EXAMS simulation but 

requires far fewer inputs and much less time and effort to use. The model uses a chemical's label 

application information, its soil/water partition data and its degradation kinetics to estimate high 

level exposure values in the same EFED “standard” agricultural field/farm pond scenario as used 

with PRZM/EXAMS simulations. The program is generic in that it does not consider differences 

in climate, soils, topography or crop in estimating potential pesticide exposure.

GENEEC is also simpler than the PRZM and EXAMS models in its treatment of hydrology. The 

linked PRZM and EXAMS models simulate the impact of daily weather on the treated 

agricultural field over a period of thirty years. During this time, pesticide is washed-off of the 

field into the water-body by twenty to forty rainfall/runoff events per year. Each new addition of 

pesticide to the water-body adds to the pesticide which has arrived earlier either through previous 

runoff events or through spray-drift and begins degrading on the day it reaches the water. 

GENEEC, on the other hand, is a single event model. It assumes one single large rainfall/runoff 

event occurs that removes a large quantity of pesticide from the field to the water all at one time. 

Longer-term, multiple-day average concentration values are calculated based on the peak day 

value and subsequent values considering degradation processes.

GENEEC2 (version 2.0) was developed in response to suggestions for improvements by model 

users, by the desire to stay current with the newer versions of the PRZM (Carsel, 1997)4 and 

EXAMS (Burns, 1997)5 programs upon which GENEEC is based and by availability of much 

improved data on spray drift and quantitative methods of estimation of offsite drift developed by 

the Spray Drift Task Force (SDTF). The main differences between versions 1.0 and 2.0 include: 

(a) an entirely new binding curve to represent dissolved concentration as a function of Kd; (b) the 

use of the binding parameter, Kd in preference to Koc to represent pesticide attachment to soil, to 

organic matter or to water-body bottom and suspended sediments; (c) a change in the 

recommendation for depth of incorporation; (d) a change in the timing of the single event 

rainstorm for chemicals which receive multiple applications; (e) addition of a subroutine from 

the SDTF to estimate spray drift; and (f) a change in the time durations of the output values to 

better match the durations of relevant toxicity tests.

Table A1 summarizes the input parameters used in GENEEC2. Table A1b summarizes output.

 4 R.F. Carsel, J.C.Imhoff, P.R.Hummel, J.M.Cheplick and J.S.Donigian, Jr. 1997. PRZM3, A Model for Predicting 

Pesticide and Nitrogen Fate in Crop Root and Unsaturated Soil Zones: User’s Manual for Release 3.0; 

Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 

Athens, GA.

5 Burns, L.A. March 1997. Exposure Analysis Modeling System (EXAMSII) Users Guide for Version 2.97.5, 

Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 

Athens, GA.
9

Table A1. Environmental Fate and Other Input Parameters for the Estimation of Naphthalene-acetic Acid, 

Ethyl Ester (Expressed in Acid Equivalents), Using GENEEC22

Parameter Value Source

Run Number 1 User Defined

Output File Name NAA-2015.txt User Defined

Chemical Name NAA (EE) Product Label1

Crop Name Pomegranate Product Label1

Application Method – diluted in a large volume of water, applied 

to the lower tree trunks and immediate surrounding area B (Ground) Product Label1

Application Rate (lb a.e./A3) 3.6 Product Label1

Applications Permitted per Season at Max. Rate 2 Product Label1

Application Interval (days) 60 Product Label1

Water Solubility (20°C) (ppm)

(Solubility for the acid. The pH is not specified.) 420 MRID# 40522903

Hydrolysis Half-Life (pH 7)

Half-life for NAA ethyl ester at pH 7 is 266 days while there are 

no hydrolysable groups in the acid (NAA).

0 (stable) MRID# 00129382

Aerobic Soil Metabolism Half-Life (days)

(3x available value = 3 x 10 days = 30 days) 30 HSDB(see USEPA 2014)

Aerobic Aquatic Metabolism Half-life (days)

(2x aerobic soil metabolism input value) 60 Per guidelines2

Aqueous Photolysis Half-Life (days) 4 Crosby & Tang 

(1969)

Adsorption/Desorption Coefficient (KOC, mL/gOC) 24.82 EPISUITE v.4.1

Pesticide is Wetted-In N (No) Product Label1

Depth of Incorporation (in) 0 Product Label1

Droplet Size Distribution (option A is the default value for ground 

applications) A (Fine) Product Label1

Nozzle Height (option B is the default; however, for these 

applications applied to the lower tree trunks and immediate 

surrounding area, option A is appropriate)

A (Low Boom 

Sprayer) Product Label1

Width of No-spray Zone (ft) 0 Product Label1

1. Proposed label for Tre-Hold® Sprout Inhibitor A-112.

2. For output from GENEEC2, refer to the Appendix B. Input parameter values were selected based on 

the Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of 

Pesticides version 2.1, dated 10/22/2009 and approved 11/10/2009. URL: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (accessed 04/08/2015).

3. The abbreviation a.e. means acid equivalent.

Table A1 b NAA EE Surface Water EECs Based on GENEEC2 Tier 1 Output

Peak (mg/L) 21-day (mg/L) 60-day (mg/L)

0.238 0.222 0.194
10

Tier 2 modeling using the Surface Water Concentration Calculator (SWCC)

A brief description of the aquatic models used in this risk assessment follows. Additional 

information about these models is provided in the Agency’s website at 

http://www.epa.gov/pesticides/science/models_pg.htm#aquatic. For agricultural and certain nonagricultural uses, exposure concentrations for surface waters assessments are estimated based on 

EFED’s Tier II aquatic model PRZM/VVWM. A graphical user interface Surface Water 

Concentration Calculator (SWCC v.1.106, May 6, 2014), developed by the EPA, was used to 

facilitate inputting chemical and use specific parameters into the appropriate input files and 

chemical files, replacing the older PE5 shell (November 2006), which used PRZM3 and 

EXAMS. The SWCC estimates pesticide concentrations in water bodies that result from 

pesticide applications to land. The calculator was designed for regulatory applications as applied 

in the Office of Pesticide Programs, USEPA, as well as PMRA, Health Canada. The calculator 

uses the Pesticide Root Zone Model (PRZM v5.0+, May 6, 2014) and the Varying Volume 

Water Body Model (VVWM, May 6, 2014, a replacement for the older EXAMS model). The 

PRZM field or orchard crop scenario is the basic file which describes the local or regional 

climatological information, soil hydrology, soil characteristics, crop characteristics, and the 

pesticide properties necessary to determine pesticide loadings to surface water. This basic file 

constitutes the first part of the “exposure scenario.” It simulates the processes in the agricultural 

field, such as runoff and erosion, on a daily time step. The runoff and erosion flux output data 

from PRZM are used as chemical loadings to the VVWM, which simulates surface water, in 

order to predict the EECs. The VVWM is conceptually similar to the current EXAMS-based 

model in that both are 2-compartment models driven by first-order processes. It simulates the 

USEPA standard water bodies (i.e., farm pond and/or index reservoir) but with greater efficiency 

and flexibility for incorporation into a user interface. The VVWM also allows for variations in 

water body volume on a daily basis due to runoff, precipitation, and evaporation. Temperature, 

wind speeds, and pesticide dissipation processes are also allowed to vary daily. EECs were 

determined using the standard pond scenario which describes a vulnerable surface water scenario 

for the VVWM component of the modeling exercise.

To model pomegranate, the CA fruit scenario was chosen. The input parameter values selected 

were for the acid since presumably the ester degrades to the acid rapidly in the environment. 

Table A2 summarizes the input parameters used in the SWCC.

Table A2. Environmental Fate and Other Input Parameters for the Estimation of Naphthaleneacetic Acid, 

Ethyl Ester (Expressed in Acid Equivalents), Using the SWCC2

Parameter Value Source

Chemical Name NAA, EE Product Label1

Crop Name Pomegranate Product Label1

Scenario CA Fruit User selected

Dates of Application (per label, apps usually occur between Feb. 

to May in the San Joaquin Valley; date of first application selected 

so both apps occur within the labeled range) (dd-mm)

15-03; 14-05 Product Label1

Application Rate (lb a.e./A)3 3.6 Product Label1

Application Rate (kg a.e./A)3 4.03 Product Label1

Applications Permitted per Season at Max. Rate 2 Product Label1
11

Table A2. Environmental Fate and Other Input Parameters for the Estimation of Naphthaleneacetic Acid, 

Ethyl Ester (Expressed in Acid Equivalents), Using the SWCC2

Parameter Value Source

Application Interval (days) 60 Product Label1

Water Solubility (ppm, 20°C)

(Solubility for the acid. The pH is not specified.) 420 MRID 40522903

Hydrolysis Half-Life (pH 7)

Half-life for NAA ethyl ester at pH 7 is 266 days while there are 

no hydrolysable groups in the acid (NAA).

0 (stable) MRID 00129382

Aerobic Soil Metabolism Half-Life (days)

(3x available value = 3 x 10 days = 30 days) 30 HSDB(see USEPA 2014)

Reference Temperature (°C) 25 Assumed

Aerobic Aquatic Metabolism Half-life (days)

(2x aerobic soil metabolism input value) 60 Per guidelines2

Reference Temperature (°C) 25 Assumed

Anaerobic Aquatic Metabolism Half-life 0 (stable) No data available

Reference Temperature (°C) 25 Assumed

Aqueous Photolysis Half-life (days) 4 Crosby & Tang

(1969)

Aqueous Photolysis Reference Latitude (°) 40 Assumed

Adsorption/Desorption Coefficient (KOC, mL/gOC) 24.82 EPISUITE v.4.1

Method of Application Ground Product Label1

Depth of Incorporation (cm) 0.0 Product Label1

Application Efficiency (fraction) 0.99 Product Label1

Spray Drift (fraction for low boom height is appropriate, droplet 

size ASABE very fine to fine is default, 90th percentile) 0.027 Product Label1

Width of No-spray Zone (ft) 0 Product Label1

Vapor Pressure (torr) 0.3 MRID 40522903

Foliar Dissipation Half-life 0 No data available

Molecular Weight (g/mol) (for the acid) 186.21 2004 RED4

1. Proposed label for Tre-Hold® Sprout Inhibitor A-112.

2. For output from the SWCC, refer to the Appendix B. Input parameter values were selected based on the 

Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of 

Pesticides version 2.1, dated 10/22/2009 and approved 11/10/2009. URL: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (accessed 04/08/2015).

3. The abbreviation a.e. means acid equivalent.

4. USEPA. 2004. Revised EFED Risk Assessment for the Naphthaleneacetic Acid Reregistration

Eligibility Decision: Revision Based on Application at Higher Use Rates (DP Barcode: D306433). 

Memorandum from A. Vaughan and J. Melendez (Environmental Fate and Effects Division) to Michael 

Goodis (Special Review and Reregistration Division) dated 10/27/2004. Office of Pesticide Programs.

Table A3. NAA EE Surface Water EECs Based on GENEEC2

Peak (mg/L) 21-day (mg/L) 60-day (mg/L)

0.238 0.222 0.194

Table A4. NAA EE Surface Water EECs Based on the SWCC

Peak (mg/L) 21-day (mg/L) 60-day (mg/L)

0.00839 0.00328 0.00131

Pore Water Peak (mg/L) Pore Water 21-day (mg/L)

0.00103 0.000995
12

Appendix B. Example Output Files

GENEEC2 Output File

 RUN No. 1 FOR NAA(EE) ON Pomegranat * INPUT VALUES * 

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

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP

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

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

 3.600( 4.500) 2 60 24.8 420.0 GRLOFI( 2.9) 0.0 0.0

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

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

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

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

 30.00 2 0.00 4.00- 496.00 60.00 53.53

 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001

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

 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

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

 238.37 235.86 222.03 194.19 175.96

EPI Suite v.4.11’s ECOSAR v.1.11 Output File

ECOSAR Version 1.11 Results Page

SMILES : O=C(OCC)Cc(c(c(ccc1)cc2)c1)c2

CHEM : 1-Naphthaleneacetic acid, ethyl ester

CAS Num: 

ChemID1: 

MOL FOR: C14 H14 O2 

MOL WT : 214.27

Log Kow: 3.748 (EPISuite Kowwin v1.68 Estimate)

Log Kow: (User Entered)

Log Kow: (PhysProp DB exp value - for comparison only)

Melt Pt: 88.50 (deg C, User Entered for Wat Sol estimate)

Melt Pt: 88.50 (deg C, PhysProp DB exp value for Wat Sol est)

Wat Sol: 14.75 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Wat Sol: (User Entered)

Wat Sol: (PhysProp DB exp value)

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

Values used to Generate ECOSAR Profile

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

Log Kow: 3.748 (EPISuite Kowwin v1.68 Estimate)
13

Wat Sol: 14.75 (mg/L, EPISuite WSKowwin v1.43 Estimate)

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

ECOSAR v1.11 Class-specific Estimations

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

Esters

 Predicted

ECOSAR Class Organism Duration End Pt mg/L 

(ppm)

=========================== ================== ======== ====== 

==========

Esters : Fish 96-hr LC50 2.730

Esters : Daphnid 48-hr LC50 4.707

Esters : Green Algae 96-hr EC50 1.519

Esters : Fish ChV 0.142

Esters : Daphnid ChV 1.947

Esters : Green Algae ChV 0.687

Esters : Fish (SW) 96-hr LC50 3.732

Esters : Mysid 96-hr LC50 1.551

Esters : Fish (SW) ChV 0.733

Esters : Mysid (SW) ChV 3.238

Esters : Earthworm 14-day LC50 763.130 

*

=========================== ================== ======== ====== 

==========

Neutral Organic SAR : Fish 96-hr LC50 4.739

(Baseline Toxicity) : Daphnid 48-hr LC50 3.162

 : Green Algae 96-hr EC50 4.591

 : Fish ChV 0.560

 : Daphnid ChV 0.483

: Green Algae ChV 1.722

Note: * = asterisk designates: Chemical may not be soluble enough to

 measure this predicted effect. If the effect level exceeds the

 water solubility by 10X, typically no effects at saturation (NES)

 are reported.

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

Class Specific LogKow Cut-Offs

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

If the log Kow of the chemical is greater than the endpoint specific cut-offs

presented below, then no effects at saturation are expected for those 

endpoints.

Esters:

------

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50)

Maximum LogKow: 6.0 (Earthworm LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)
14

Baseline Toxicity SAR Limitations:

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

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)
15

SWCC Output File

Summary of Water Modeling of NAA, EE and the USEPA Standard Pond

Estimated Environmental Concentrations for NAA, EE are presented in Table 1 for the USEPA standard 

pond with the CAfruit_WirrigSTD 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). Critical input values for the model are summarized in Tables 2 and 3.

This model estimates that about 0.3% of NAA, EE applied to the field eventually reaches the water body. 

The main mechanism of transport from the field to the water body is by spray drift (90.8% of the total 

transport) followed by runoff (9.16%).

In the water body, pesticide dissipates with an effective water column half-life of 6.1 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 = 6.7 days) followed by metabolism (90.8 days) and photolysis 

(383.1 days).

In the benthic region, pesticide is stable. Most of the pesticide in the benthic region (73%) is sorbed to 

sediment rather than in the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for NAA, EE.

Peak (1-in-10 yr) 8.39

4-day Avg (1-in-10 yr) 6.42

21-day Avg (1-in-10 yr) 3.28

60-day Avg (1-in-10 yr) 1.31

365-day Avg (1-in-10 yr) 0.341

Entire Simulation Mean 0.281

Table 2. Summary of Model Inputs for NAA, EE.

Scenario CAfruit_WirrigSTD

Cropped Area Fraction 1

Koc (ml/g) 24.82

Water Half-Life (days) @ 25 °C 60

Benthic Half-Life (days) @ 25 °C 0

Photolysis Half-Life (days) @ 40 °Lat 4

Hydrolysis Half-Life (days) 0
16

Soil Half-Life (days) @ 25 °C 30

Foliar Half-Life (days) 0

Molecular Wt 186.21

Vapor Pressure (torr) 0.3

Solubility (mg/l) 420

Table 3. Application Schedule for NAA, EE.

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

03/15 Ground 4.03 0.99 0.027

05/14 Ground 4.03 0.99 0.027

Figure 1. Yearly Peak Concentrations