Document ID: EPA-HQ-OPP-2008-0554-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-06-02T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

                                                                     
OFFICE OF 

                                                                 
PREVENTION, PESTICIDES AND

                                                                   
TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 								PC Code 	107091

				DP Barcode	D352617

MEMORANDUM

DATE:	February 10, 2009

SUBJECT:	Tier I Estimated Drinking Water Concentrations of Etoxazole,
and Its Transformation Products R-8 and R-13, for the Use in the Human
Health Risk Assessment:  IR-4 Petition for the Use of the Chemical on
Stone Fruits (Group 12), Indoor Grown Tomato, Cucumber and Mint

TO:		Debra Rate, Ph.D., Biologist

		Sidney Jackson, Risk Manager Reviewer

		John Redden, Team Leader

		Daniel Rosenblatt, Chief 

		Alternative Risk Integration and Assessment Team

		Risk Integration Minor Use and Emergency Response Branch

		Registration Division (7505P)

FROM:	José Luis Meléndez, Chemist

		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)

This memo presents the Tier I Estimated Drinking Water Concentrations
(EDWCs) for etoxazole, and for its major transformation products R-8 and
R-13, calculated using the Tier I aquatic models FIRST (surface water)
and SCI-GROW (ground water) for use in the human health risk assessment.
 The registrant seeks registration for the uses of the chemical on stone
fruits (Group 12), indoor grown tomato, cucumber and mint. 

Exposure to surface water is possible through surface water runoff, soil
erosion, and off-target spray drift.  Due to relatively high adsorption
of etoxazole (slightly mobile to hardly mobile, KOC’s on the order of
~5000 to ~55,000 mL/g, FAO classification), the exposure to ground
waters is expected to be moderately low.  The Tier I Estimated Drinking
Water Concentrations (EDWCs) for etoxazole and for its major
transformation products R-8 and R-13 (as requested by HED), calculated
using FIRST (surface water) and SCI-GROW (ground water) for use in the
human health risk assessment were as follows:  For etoxazole surface
water, the acute value is 6.07 ppb and the chronic value is 0.618 ppb. 
The groundwater screening concentration of etoxazole for both acute and
chronic is 0.00346 ppb (or 3.46x10-3 ppb).  For R-8 surface water, the
acute value is 8.03 ppb and the chronic value is 4.08 ppb.  The
groundwater screening concentration of R-8 for both acute and chronic is
0.742 ppb.  For R-13 surface water, the acute value is 1.63 ppb and the
chronic value is 0.063 ppb.  The groundwater screening concentration of
R-13 for both acute and chronic is 0.000644 ppb (or 6.44x10-4 ppb)
(please, refer to Table 1).

A more definitive assessment could be performed, using Tier II aquatic
models PRZM/ EXAMS. Should any questions arise, please, contact José L.
Meléndez at 787-977-5856 or 787-946-9988.

Identification of specific data gaps:

No major data gaps were identified.

EXECUTIVE SUMMARY 

   

Etoxazole: CAS name:
2-(2,6-difluorophenyl)-4-[4-(1,1-dimethylethyl)-2-ethoxyphenyl]-4,5-dihy
drooxazole; IUPAC name:
(RS)-5-tert-butyl-2-[2-(2,6-difluorophenyl)-4,5-dihydro-1,3-oxazol-4-yl]
phenetole; CAS number 153233-91-1; PC Code 107091; and molecular formula
C21H23F2NO2; is an acaricide/ miticide.  Its chemical class is diphenyl
oxazoline.  The registrant, Valent U.S.A. Corporation, has claimed in a
prior submission (02/15/02) that they have not yet determined a mode of
action, but states that “it appears to control susceptible mites by
inhibiting the molting process through disruption of the cell
membrane.”  It reportedly works by contact of the mite juvenile stages
(eggs to nymphs), but does not kill adult mites.  Recent work by Nauen &
Smagghe (Ref. 11), suggests that etoxazole’s mode of action is
inhibition of chitin (the main component of the oxoskeletons of
arthropods and insects, and the cell walls of fungi) biosynthesis.

 28% other ingredients:  ZEAL™ MITICIDE, ZEAL™ WP Miticide, and
SECURE Miticide.  An additional product, TetraSan™ 5 WDG, contains 5%
active ingredient.  The proposed uses are stone fruit group 12 (e.g,
nectarine, peach, plum, prune-fresh), indoor grown tomato, mint and
cucumber.  The application methods vary depending on the crop.  For
cotton and mint, applications may be by ground or aerial methods.  For
pome fruits, non-bearing fruits, and tree nuts, the applications may be
by ground methods via airblast.  For other crops, the applications are
by ground spray methods.

 

The models used for this screening-level assessment (Tier I) are FIRST
and SCI-GROW, with the crop with the maximum application rate (mint),
the maximum PCA (0.87, or national default) and aerial applications. 
Two degradates were modeled along with etoxazole, R-8
[2-amino-2-(4-tert-butyl-2-ethoxyphenyl)-ethanol], and R-13
[4-(4-tert-butyl-2-ethoxyphenyl)-2-(2,6-difluorophenyl)-oxazole] (as
requested by HED).  The total residues approach was not utilized because
it was found that the mobility characteristics of the transformation
products were different than those of the parent, furthermore, the
structures of the transformation products were not necessarily similar
to the parent (refer to a summary of the results in Table 1, and
structures in the Appendix).

For this DWA, it has been assumed that at a given time, the maximum
amount of etoxazole has been applied to the field, and, at the same
time, certain amounts of R-8 and R-13 are applied by “granular”
method.  The EFED acknowledges that this approach does not achieve mass
balance, that is, the amount of pesticide plus degradates applied
exceeds the maximum application rate.  However, the Division believes
that the results obtained are suitable for a screening level assessment
and are conservative.

 

There is considerable uncertainty concerning the various degradates of
etoxazole (some of which are relatively persistent).  The absence of
full environmental fate information about such degradates constitutes an
uncertainty at this time.  There is also uncertainty in the role of
various competing dissipation and/or degradation mechanisms of
etoxazole.  Various studies have been deemed supplemental.  Despite
these facts, the EFED believes that this assessment is conservative. 

Table 1 provides a summary of Tier I modeled drinking water
concentrations of etoxazole, R-8 and R-13.  Additional refinements of
the assessment can be developed with higher tier analysis, if requested
by HED. 

Table 1.  Maximum Tier I Estimated Drinking Water Concentrations (EDWCs)
for drinking water risk assessment based on ground application of
etoxazole, based on one application on mint at 0.36 lb a.i./A/season.

Chemical	

Acute EDWC Surface Water FIRST (ppb)	

Chronic EDWC Surface Water  FIRST (ppb)*	

Acute and Chronic EDWC Ground Water  SCI-GROW (ppb)*

Etoxazole	6.07	0.618	0.00346

R-8	8.03	4.08	0.742

R-13	1.63	0.063	0.000644

* Results presented in ppb of the chemical, as opposed to ppb of parent
equivalent.

PROBLEM FORMULATION

This is a Tier I drinking water assessment that uses modeling and
monitoring data, if available, to estimate the ground water and surface
water concentrations of pesticides and transformation products in
drinking water source water (pre-treatment) resulting from pesticide use
on sites that are highly vulnerable.  This initial tier screens out
chemicals with low potential risk and provides estimated exposure
concentrations for the human health dietary risk assessment.

  

Tier 1 drinking waters assessments were issued on 4/29/03 and 4/24/07
(refer to Table 2), using FIRST and SCI-GROW, but the current most
conservative scenario was now found to be mint (seasonal application
rate 0.36 lb a.i./A, divided into two applications, and aerial
application).  The present action triggers the need for a new drinking
waters assessment because the uses have a higher seasonal rate of
application.

Table 2.  Summary of Etoxazole Drinking Water Exposure Assessments

Date	Reference	Uses included	Model(s)1

4/29/03	D289664	Pome fruit, cotton, strawberry	FIRST (SW). SCI-GROW (GW)

4/24/07	D335338	Cherry, melon (subgroup 9A), hops	FIRST (SW), SCI-GROW
(GW)

7/26/07	D341221	Increased application rate for cotton	No new modeling
required

This assessment	D352617	Stone fruits (group 12), indoor grown tomato,
cucumber and mint	New modeling is required with FIRST (SW) and SCI-GROW
(GW)

1 SW =surface water; GW = ground water.  The bolded use was the modeled
use.

For etoxazole, the following drinking water hypothesis is being employed
for this assessment:

Etoxazole use in accordance with the label, results in potential
contamination of both, surface and ground water resources, with
etoxazole and its relevant degradates R-8 and R-13.

The conceptual site model is a generic graphic depiction of the risk
hypothesis.  Through a preliminary iterative process of examining
available data, the conceptual model (i.e., the drinking water
hypothesis) has been refined to reflect the likely exposure pathways
that are most relevant and applicable to this assessment (refer to the
following figure).

Etoxazole is applied to the field via aerial (for cotton and mint) and
ground methods (for other crops).  Crop absorption may be important, but
crop uptake is not expected to be important because etoxazole binds to
soils (relatively high Kd and KOC values). In addition, spray drift is
an important factor in the contamination of nearby surface waters
because etoxazole is applied foliarly. As the field may be kept
irrigated and the soils are wet, large runoff events, accompanied with
erosion, may be a factor in horizontal movement due to the tendency of
the chemical to remain bound to the soils (high tendency to partition
with the soils).  Since etoxazole shows moderate persistence in
laboratory and field studies, it may be available for moderate periods
of time (on the order of weeks to months in aerobic media and several
months in anaerobic media). Vertical movement to subsurfaces is not
expected to be very important in the dissipation of etoxazole. 
Volatilization is expected to be a relatively minor route of dissipation
for the active ingredient (etoxazole has a relatively small vapor
pressure and Henry’s Law Constant).  The relevant degradates observed
in the laboratory studies are R-8 and R-13, and are expected to be
present in the field.

ANALYSIS

Use Characterization

A summary table of all use patterns, highlighting Tier I modeled use, is
illustrated below (Table 3).

Zeal™ WP Miticide, Secure™ Miticide, and Zeal™ Miticide label(s). 
New uses are shaded yellow, while modeled use is bolded and underlined.

USE	SINGLE  APP. RATE  (lb. a.i./A)	NUMBER OF APPS.	SEASONAL APP. RATE  
 (lb. a.i./A)	INTERVAL BETWEEN APPS. (days)	APP. METHOD	PHI (days)

Indoor grown Tomato	0.125	2	0.27	21	Foliar spray	1

Cucumber	0.135	2	0.27	21	Ground	7

Mint	0.18	2	0.36	21	Ground, aerial	7

Stone fruit (apricot, sweet and tart cherry, nectarine, peach, plum,
chicksaw plum, damson plum, Japanese plum, plumcot, fresh prune)	0.135	2
0.27	14	Ground	7

Cotton	0.045	1	0.045	N/A	Ground, aerial	28

Grape	0.135	1	0.135	N/A	Ground	14

Pome Fruit (apple, crabapple, loquat, pear, quince)	0.135	1	0.135	N/A
Ground with airblast equipment	14-28

Strawberry	0.135	1	0.135	N/A	Ground	1

Non-Bearing Fruit Trees	0.135	1	0.135	N/A	Ground with airblast equipment
365

Christmas Trees	0.135	1	0.135	N/A	Ground	N/A

Tree Nuts [almond, beech nut, Brazil nut, butternut, cashew, chinquapin,
filbert (hazelnut), hickory nut, macadamia nut, pecan, pistachio, walnut
(black, English)]	0.135	1	0.135	N/A	Ground with airblast equipment	28

Melon Subgroup 9A (cantaloupe, citron melon, muskmelon, watermelon)
0.135	1	0.135	N/A	Ground	7

Hop	0.18	1	0.18	N/A	Ground	7

Etoxazole may be applied to a number of agricultural crops, including
cotton, grape, pome fruit, tree nuts, melon and indoor grown tomatoes (a
proposed use).  It may also be applied on ornamental plants, Christmas
trees, non-bearing fruit trees and others.  There are various
application methods for this miticide. It can be applied aerially or by
ground methods to cotton and mint (mint is a proposed use).  It may be
applied by ground methods via ground spray or airblast to all other
crops (no aerial applications for other crops).

The use pattern selected for modeling was mint.  It involved the highest
application rate among all the crops, and aerial applications.  Even
though cotton may be applied aerially, it involves a much smaller
application rate, and certain crops may be applied by airblast, but
their application rate is also smaller than for mint.  Mint utilizes the
highest PCA, with the default of 87%.  The interval between applications
does not apply in many instances, because for those crops only one
application is allowed per season.

Fate and Transport Characterization

A physical/chemical and environmental fate/transport properties detailed
summary table for the pesticide is included in this section.  It
includes measured parameters, values, data sources, and comments (Table
4).

  SEQ CHAPTER \h \r 1 Table 4.  Summary of physicochemical and
environmental fate and transport properties of etoxazole and
transformation products.

PARAMETER	VALUE(S) (units)	SOURCE	COMMENT

  Chemical Name
2-(2,6-difluorophenyl)-4-[4-(1,1-dimethylethyl)-2-ethoxyphenyl]-4,5-dihy
drooxazole	_	CAS name

  Molecular Weight	359.42 g/mole	_	–

  Solubility (20°C)	0.075 mg/L or ppm	MRID: 45089902 and 45089903.	–

  Vapor Pressure (20°C)	7 x 10-6 mmHg	MRID: 45089902.	–

  Henry’s Law constant	8.5 x 10-6 atm-m3/mol	_	Estimated from vapor
pressure and water solubility.

  pKa (20°C)	Not available	Not Applicable	–

 Octanol-Water Partition Coefficient  (KOW)	3.31x105	MRID: 45089902.	–

  Hydrolysis Half-life 

  [pH 5, 7, 9; (20°C)]	pH 5 9.6 days;  pH 7 ~stable (99 days); pH 9
~stable (98 days)	MRID: 45090017.	_

  Aqueous Photolysis Half-life 

  (pH 7)	28.8 days of 12 hours of sunlight/ 12 hours dark; 34 days,
based on solar readings in Dublin, CA	MRID: 46658101.	Dark control
corrected.

  Soil Photolysis Half-life	CL from UK, t1/2  = 19.3 days	MRID:
45090020, 46299904.	–

  Aerobic Soil Metabolism Half-life	Study performed using
[U-14C-tert-butylphenyl] and [U-14C-difluorophenyl] radiolabels

SL from UK 10.2-12.0 days.

SL from CA 19.4-23.2 days.

Studies performed using [U-14C-tert-Butylphenyl] radiolabel

S from Germany 12.7 days.

LS from Germany 21.5 d.  CL from UK 44.7 days.  SL from UK 26.2 days
(@10(C).  SL from UK, same soil as above @30(C, 2.3 days.	MRID:
45090019, 45090021, 45090022.	_

  Anaerobic Soil Metabolism   

  Half-life	SL from UK 101.9-111.8 days.

	MRID: 45090023.	–

  Anaerobic Aquatic Metabolism   

  Half-life	Water clay sed. from Greenville, MS 138-155 days.  Etoxazole
was associated with the sediment.	MRID: 45621718.	–

  Aerobic Aquatic Metabolism 

  Half-life	Not available	Not Applicable	–

  Organic Carbon Partition

  Coefficient (KOC), Parent Etoxazole	5420, 5230, 11000, 4910, 18000,
23100, 55300, 14200 mL/gOC

	MRID: 45090024, 45090026, 46299905, 46299906.	For SL, CL, S, LS, SL,
SL, SL and SL soils, respectively

  Soil Partition Coefficient (Kd), Parent Etoxazole	131, 68, 66, 103,
156, 335, 193, 156  mL/g	MRID: 45090024, 45090026, 46299905, 46299906.
For SL, CL, S, LS, SL, SL, SL and SL soils, respectively

  Organic Carbon Partition

  Coefficient (KOC), Transformation Product R-7	1125, 7540, 2330 mL/gOC

	MRID: 45250906.	For SL, CL and S soils, respectively

  Soil Partition Coefficient (Kd), Transformation Product R-7	27, 98, 14
 mL/g	MRID: 45250906.	For SL, CL and S soils, respectively

  Organic Carbon Partition

  Coefficient (KOC), Transformation Product R-8	103, 351, 207 mL/gOC

	MRID: 45250907.	For SL, CL and S soils, respectively

  Soil Partition Coefficient (Kd), Transformation Product R-8	2.48,
4.56, 1.24 mL/g	MRID: 45250907.	For SL, CL and S soils, respectively

  Organic Carbon Partition

  Coefficient (KOC), Transformation Product R-13	36540, 83230, 13670
mL/gOC

	MRID: 45250908.	For SL, CL and S soils, respectively

  Soil Partition Coefficient (Kd), Transformation Product R-13	877,
1082, 82 mL/g	MRID: 45250908.	For SL, CL and S soils, respectively

  Terrestrial Field Dissipation 

  Half-life	St. Martin des Bois (Northern France) SiCL; DT50=8 days

Montech (Southern France)

CL; DT50=8 days

Senas (Southern France)

CL; DT50=4 days

Schleithal (Northern France)

SiL; DT50=9 days

The degradate R-8 was no detected at any test interval.

Bare ground in Santa Cruz Co., CA, SL; t½=7.0 days, major product
detected R-7 (generally 0-7.5 cm soil layer)

Bare ground in Payette Co., ID, SL; t½=11.7 days, major product
detected R-7 (only in the 0-7.5 cm soil layer)

Bare ground in Washington Co., MS, SiL; t½=<1 day, major product
detected R-7 (only in 0-7.5 cm soil layer)	MRID: 45250909, 45621721,
45621722, 45621723.	_

Accumulation in Fish    (Maximum BCF)	1600X for edible tissues

4700X for nonedible tissues

3300X for whole fish

After 5 days depuration, 70-78% of the [14C]residues were depurated (t½
depuration estimated at 2.6 days for edible tissues, and 4.6-6.2 days
for non-edible tissues).	MRID: 45621615, 46269907.	_

Based on a number of valid and supplemental studies, it appears that the
major routes of dissipation of etoxazole are aqueous and soil photolysis
(half-lives 28.8-34 and 19.3 days, respectively), and aerobic soil
metabolism (half-lives ranging from 10.2 to 44.7 days, n=7).  The
relatively high soil organic carbon adsorption coefficient (generally,
KOC > 5000), of etoxazole, indicates that it may not be a direct threat
to ground waters; however, modeling results indicated that it may reach
levels in adjacent bodies of water.

Important transformation products of etoxazole appear to be R-4, R-7,
and R-8.  Of these, R-8 is more mobile and relatively persistent.  R-7
shows moderate mobility.  Etoxazole is stable to hydrolysis at a range
of pHs, and compared to the aerobic conditions, the anaerobic metabolism
is a relatively minor route of dissipation of etoxazole (half-lives were
>100 days).  The major transformation products were R-11 in an anaerobic
soil metabolism study and R-11 and R-4 in an anaerobic aquatic
metabolism study.

Etoxazole was slightly to hardly mobile (FAO classification) in batch
equilibrium studies conducted on 8 soils (KF range 66-335; KFOC range
4910-55300).

Three field dissipation studies, conducted in bare soils in California
(Elder sandy loam soil, representative of a typical strawberries site),
Idaho (Cashmere sandy loam soil, representative of a typical apples
site), and Mississippi (Dundee silt loam soil, representative of a
typical cotton site), confirmed that etoxazole is relatively short lived
(half-lives ranged from <1 day to 11.7 days).  The only transformation
product observed in the field in substantial amounts was R-7 (generally
detected only in the 0-7.5 cm soil depth).  It should be noted that all
three terrestrial field dissipation studies were conducted in bare
ground sites.  For terrestrial field dissipation studies conducted in
cropped sites, generally the chemicals show higher persistence.

Etoxazole shows a significant potential to bioaccumulate, as expected
from its very high octanol/water partition coefficient (331,000). 
Residues bioaccumulated in Rainbow trout with maximum bioconcentration
factors of 1600x for the edible tissue, and 3300x for whole fish. 
However, depuration was relatively rapid (half-life 2.6 days for edible
tissue).

The summary of the various degradation products formed by each process
in the studies reviewed is provided in the following table (Table 5).

Table 5.  Summary of degradate formation from degradation of etoxazole.

STUDY TYPE	DEGRADATE and MAXIMUM CONCENTRATION	SOURCE

	R-4 (% applied)	R-7 (% applied)	R-13 and others (% applied)

	  Hydrolysis	60.6% @ 21 days, pH 5	13.0% @ 30 days, pH 7	_	MRID:
45090017.

  Aqueous Photolysis	_	_	R-11, 30.2% at 14 days, study termination.
MRID: 46658101.

  Soil Photolysis	_	_	R-3, 11.7% @ 295 hr; R-11, 12.0% @ 295 hr or study
termination	MRID: 45090020, 46299904.

  Aerobic Soil Metabolism	11.9% @ 30 days	21.6% @ 7 days	30.0% @ 62
days; R-8, 44.8% @/ 60 days; R-3 10.4% @ 61 days, various studies	MRID:
45090019, 45090021, 45090022.

  Anaerobic Soil Metabolism	_	_	Major degradates R-8, R-11	MRID:
45090023.

 Anaerobic Aquatic Metabolism 

	_	_	Major degradates R-11, R-4	MRID: 45621718.

 Terrestrial Field Dissipation	_	Detected in 0-7.5 cm layer	_	MRID:
45250909, 45621721, 45621722, 45621723.

The major degradates observed in the hydrolysis study were R-4 and R-7. 
In the aqueous photolysis study, the major transformation product was
R-11.  In the soil photodegradation study, the major transformation
products were R-3 and R-11.  In various aerobic soil metabolism studies,
various transformation products were observed: R-4, R-7, R-13, R-8 and
R-3.  Under anaerobic conditions R-11 was common to the anaerobic soil
metabolism study, and the anaerobic aquatic metabolism study. 
Furthermore, R-4 and R-8 were observed.  Important transformation
products of etoxazole appear to be R-4, R-7, and R-8.  Of these, R-8 is
more mobile and relatively persistent.  R-7 shows moderate mobility (see
below).  There are uncertainties regarding the degradation products
because, different ones were observed in different studies, a closer
inspection of the transformation products yielded the proposed
transformation pathway that follows.  In general, the aerobic soil
metabolism of etoxazole proceeds via oxidation and hydroxylation of the
dihydrooxazole ring.  Further degradation of open ring moieties of
etoxazole results in benzene-ring cleavage via dehalogenation, halogen
replacement, oxygenolytic halogen-carbon bond cleavage, and ortho- and
meta-cleavage.  Ring cleavage is followed by halogen elimination,
leading to transformation into smaller molecules that are eventually
mineralized to CO2.

R-7 appeared to be more mobile than etoxazole in two of the soils, and
of similar mobility in one soil, it was slightly mobile (FAO
classification) in batch equilibrium studies conducted on 3 soils (KF
range 14-98; KFOC range 1125-7540).  R-8, on the other hand, was more
mobile than the parent, it was moderately mobile (FAO classification) in
batch equilibrium studies conducted on 3 soils (KF range 1.24-4.56; KFOC
range 103-351).  R-13 was less mobile than etoxazole, it was hardly
mobile (FAO classification) in batch equilibrium studies conducted on 3
soils (KF range 82-1082; KFOC range 13670-83230).

Drinking Water Exposure Modeling

  SEQ CHAPTER \h \r 1 

Models (Ref. 1)

SCI-GROW v.2.3 (v 2.3, 8/5/03) (Screening Concentration in Ground Water)
is a regression model used as a screening tool to estimate pesticide
concentrations found in ground water used as drinking water.  SCIGROW
was developed by fitting a linear model to groundwater concentrations
with the Relative Index of Leaching Potential (RILP) as the independent
variable.  Groundwater 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 SCIGROW represents the concentrations that
might be expected in shallow unconfined aquifers under sandy soils,
which is representative of the ground water most vulnerable to pesticide
contamination likely to serve as a drinking water source.  (Ref. 2)

FIRST (v 1.1.1, 4/4/08) (FQPA Index Reservoir Screening Tool) is a
metamodel of PRZM and EXAMS used as a screening tool to estimate
pesticide concentrations found in surface water used as drinking water. 
FIRST was developed by making multiple runs of PRZM using varying
sorption coefficients and determining the concentration in the EXAMS
index reservoir scenario after a two-inch single storm event.  (The
Index Reservoir is a standard water body used by the Office of Pesticide
Programs to assess drinking water exposure (Office of Pesticide
Programs, 2002).  It is based on a real reservoir (albeit not currently
in active use as a drinking water supply), Shipman City Lake in
Illinois, that is known to be vulnerable to pesticide contamination.) 
The single runoff event moves a maximum of 8% of the applied pesticide
into the reservoir.  This amount can be reduced by degradation or
effects of binding to soil in the field.  Additionally, FIRST can
account for spray drift and adjusts for the area within a watershed that
is planted with the modeled crop (Percent Cropped Area).   Spray drift
(modeled as direct deposition of the pesticide into the reservoir) is
assumed to be 16% of the applied active ingredient for aerial
application, 6.3% for orchard air blast application, and 6.4% for other
ground spray application. Despite being a single event model, FIRST can
account for spray drift from multiple applications.  The default
agricultural Percent Cropped Area (PCA) is 87%.  The PRZM scenario used
for FIRST development was among the most vulnerable, and thus resulting
surface water concentrations represent the upper bound values on the
concentrations that might be found in drinking water from the use of a
pesticide.  (Ref. 3 and 4)

For volatile and semi-volatile compounds, Tier I modeling will tend to
over-estimate surface water EDWCs because there are no parameters in
FIRST that explicitly take into account volatility (i.e., no vapor
pressure or Henry’s Law Constant inputs).  Therefore, in reality, more
of the compound will be volatilizing than Tier I can account for.  If
drinking water levels of concern are exceeded for over-estimated Tier I
surface water EDWCs, Tier II modeling will be able to refine these EDWCs
by including volatility, Henry’s Law Constant, diffusion in air, and
enthalpy considerations.  Since SCI-GROW is a regression model developed
from actual pesticide data with a range of volatilities, systematic
conclusions cannot be drawn about over or underestimation of groundwater
EDWCs at Tier I. 

Modeling Approach and Input Parameters

Etoxazole labels indicate that the worst case scenario is for mint. The
crop was chosen for this assessment because the label permits use of the
maximum application rate of 0.18 pounds active ingredient per acre with
two applications at 21-day intervals.  The assessment uses the default
percent cropped area (PCA) of 0.87.  Laboratory studies indicate that
the major mechanisms of degradation are aerobic metabolism, soil
photodegradation and aqueous photolysis.  Tables 6 and 7 summarize the
input values used in the model runs for SCI-GROW and FIRST,
respectively.  The lowest non-sand Kd was used in FIRST.  The lowest KOC
value was used in SCI-GROW because there was greater than three-fold
variation in the values.  There were seven available aerobic soil
metabolism half-lives for etoxazole, obtained in five soil types and two
radiolabel positions.  The upper confidence bound value (90th
percentile) of the half-life was used for the aerobic soil metabolism in
FIRST.  The median half-life was used in SCI-GROW modeling.  The
modeling results associated with maximum allowable rate per year (0.18
lb a.i./A) are presented in Table 1.  Attached to this memorandum
(Appendix) are copies of the original printouts generated from FIRST and
SCI-GROW runs.

The primary transformation products of concern are R-8 and R-13 (as
requested by HED).   They were also simulated using the screening
models, FIRST and SCI-GROW.  EFED had only limited environmental fate
data for these transformation products; however, mobility data, a very
important parameter in the screening models, were available.  In the
absence of suitable data, it was assumed that the transformation
products were very persistent, and the half-lives were set to stable to
hydrolysis and to aqueous photolysis.  There are seven available aerobic
soil metabolism study results for the parent etoxazole.  Three of those
studies provided useful data about the decay of R-8 under such
conditions.  Two studies provided useful data for R-13.  Based on the
decay of these degradates, half-lives were estimated.  The upper
confidence bound value (90th percentile) was used in FIRST, and the mean
value for SCI-GROW.

R-8 reached a maximum of 44.8% of the applied parent in one aerobic soil
metabolism study. It is simulated by multiplying the label application
rate by 44.8%.  R-13 reached a maximum of 30.0% of the applied parent in
one aerobic soil metabolism study.   It is simulated by multiplying the
label application rate by 30.0%.  It is noted that by selecting the
highest percentage observed out of all seven studies, the results are
likely overestimations (particularly of the peak values), and represent
upper-bound estimates of the concentrations that might be found in
surface waters and ground waters due to the use of etoxazole on mint at
the maximum application rate.  In the FIRST simulation it was assumed
that the formulation was granular.  The reason is that FIRST assumes
that there is no spray drift for that type of formulation.  Drift is not
expected for a degradate formed in aerobic soil conditions.  The input
parameters for R-8 and R-13 are presented in Tables 6 and 7.

, n≥4                     Mean n=3                                    
   Mean n=2

1 Parameters are selected as per Guidance for Selecting Input Parameters
in Modeling the Environmental Fate and Transport of Pesticides; Version
II, February 28, 2002.

Table 7. FIRST (v.1.1.1) input parameter values for etoxazole, R-8 and
R-13, use on mint1.

PARAMETER (units)	Value(s) for Etoxazole	Value(s) for R-8	Value(s) for
R-13	SOURCE	COMMENT

Application Rate (lb a.i./A)	0.18	0.0533(3)	0.0537(4)	Proposed label.
Refer to comments 3 and 4 below.

Number of Applications	2	2	2	Proposed label.	Represents
most-conservative scenario in which the total maximum rate per year is
applied in two applications.

Interval between Applications (days)	21	21	21	Proposed label.	_

Percent Cropped Area (decimal)	0.87	0.87	0.87	Proposed label.	National
default.

Soil Partition Coefficient (Kd; (mL/g) or KOC (mL/gOC))	Kd=68 (9)
KOC=103 (9)	Kd=877 (9)	MRID: 45090024, 45090026, 46299905, 46299906,
45250907, 45250908	(9) Represents the lowest non-sand Kd value among
eight values ranging from 66 to 335 mL/g (etoxazole).                 
Lowest non-sand KOC among three ranging from 103 to 351mL/g.(R-8).    
Lowest non-sand Kd value Among three ranging from 82 to 1082
mL/g.(R-13). 

Aerobic Soil Metabolism Half-life (days)	26.9 (5)	473 (5)	715 (5)	MRID
45090019, 45090021, 45090022	(5)Upper confidence bound value, 90th
percentile, from 7 values (etoxazole).    From 3 values (R-8).          
                  From 2 values (R-13).

Wetted in?	No	No	No	Proposed label.	_

Depth of Incorporation (inches)	0	0	0	Proposed label.	–

Method of Application	Aerial spray	Ground/ Granular	Ground/ Granular
Proposed label.	Granular application for the degradates because drift is
not expected for them.

Solubility in Water (mg/L or ppm)	0.075	>>5.0 (2)	683 (2)	MRID#
45089902, 45089903, 45250907, 45250908	Refer to comment (2) below.

Aerobic Aquatic Metabolism Half-life (days)	53.8 (6)	946 (6)	1430 (6)
MRID 45090019, 45090021, 45090022	(6) 2X the aerobic soil metabolism
input.

Hydrolysis Half-life @ pH 7 (days)	Stable 	Stable 	Stable 	MRID#
45090017	Relatively stable for etoxazole.  No data available for R-8 and
R-13, assumed stable.

Aquatic Photolysis Half-life  @ pH 7 (days)	34	Stable 	Stable 	MRID
46658101	Highest available value for the parent.  No data available for
R-8 or for R-13, assumed stable.

1 Parameters are selected as per Guidance for Selecting Input Parameters
in Modeling the Environmental Fate and Transport of Pesticides; Version
II, February 28, 2002

2. Water solubility was provided in the mentioned study for the compound
in 0.01 M CaCl2.

3. Maximum concentration observed in the aerobic soil metabolism study
by application rate by mole ratio = 

                                                                        
                                             
(0.448)(0.18)(237.4/359.42) = 0.0533

4. Maximum concentration observed in the aerobic soil metabolism study
by application rate by mole ratio =

                                                                        
                                              
(0.300)(0.18)(357.4/359.42) = 0.0537

The Percent Cropped Area (PCA) used was the national default of 0.87
(options for Tier I are national scale cotton, wheat, corn, soybeans, or
default; regional PCAs are a Tier II tool intended for refined
assessment). (Ref. 6)

Modeling Results

Table 8 provides a summary of the modeling results for all model runs.

Table 8.  Maximum Tier I Estimated Drinking Water Concentrations (EDWCs)
for drinking water risk assessment based on ground application of
etoxazole, based on two applications on mint at 0.18 lb a.i./A each.*

Chemical	

Acute EDWC   Surface Water FIRST (ppb)	

Chronic EDWC Surface Water  FIRST (ppb)	

Acute and Chronic EDWC Ground Water  SCIGROW (ppb)

Etoxazole	6.07	0.618	0.00346

R-8	8.03	4.08	0.742

R-13	1.63	0.063	0.000644

* Results presented in ppb of the chemical, as opposed to ppb of parent
equivalent.

SCI-GROW concentration (ppb) represents the groundwater concentration
that might be expected in shallow unconfined aquifers under sandy soils.
Output is used for both acute and chronic endpoints.

FIRST concentrations (ppb) represent untreated surface water
concentrations.

 

The one-in-10-year peak day concentration is used for acute endpoints
and the one-in-10-year annual average concentration is used for chronic
endpoints. 

The estimated concentrations provided in this assessment are
conservative estimates of concentrations in drinking water.  If dietary
risks require refinement, higher tiered crop-specific and
location-specific models and modeling scenarios can be used.

Monitoring Data

No monitoring data are readily available for etoxazole.

Drinking Water Treatment

Due to relatively high adsorption of etoxazole (slightly mobile to
hardly mobile, KOC’s on the order of ~5000 to ~55,300 mL/g, FAO
classification), it is likely that primary treatment may reduce the
levels of etoxazole due to its tendency to bind.  However, there is no
information available at this time to determine the levels of reduction.
 The softening of drinking water generally results in an increase in pH.
 However, etoxazole was relatively stable to hydrolysis at a pH range of
5 – 9 at environmental temperature.  In general, it appears that
softening should not result in increased/ decreased dissipation from
hydrolysis (Ref. 9).

CONCLUSIONS 

A strength of this assessment is the availability of numerous Kd and KOC
values (eight each for the parent and three each for both of the
degradates), and numerous aerobic soil metabolism values (seven, three
and two for etoxazole, R-8 and R-13, respectively).  In addition, there
were data on the solubility of the degradates (obtained from batch
equilibrium studies, in 0.01 M CaCl2, a suitable surrogate for the
solubility of these degradates in water). However, the decay rates of
the degradates were derived from studies performed on the parent, and
may have included a smaller number of data points.  It was noted that
there is a high variability in the KOC values for etoxazole when
comparing the two studies available; nevertheless both studies indicated
relatively low mobility for the chemical.  The Kd was considered a
better predictor of the mobility of etoxazole and R-13 (the relative
standard deviation was smaller).  On the other hand, for R-8, the KOC
was found to be the best predictor of the mobility of the chemical.

A weakness of the assessment was the lack of an aerobic aquatic
metabolism study.  For the three chemicals, it was assumed that the
input value for the aerobic aquatic metabolism was twice the aerobic
soil metabolism input value, as per current guidance.  This absence of
real aerobic aquatic metabolism values was translated in the use of
input values of 946 days for R-8 and 1430 days for R-13.  While it is
possible that these chemicals are as persistent as indicated by those
values, it is also possible that the real values are lower.  The net
effect of using estimated values appears to be the overestimation of the
chronic EDWCs.

The application rate modeled in this assessment is the maximum one (0.18
lb a.i./A), with the minimum interval between applications (21 days) and
two applications (representing the use of etoxazole on mint) to obtain
EDWCs to be used nationwide.  It appears that the scenario selected will
be protective and conservative.  There are no data on what will be the
typical rate and interval (the modeled use is one of the proposed new
uses).  It is also unknown if the scenario represents what will be a
major or minor use for etoxazole.  According to the label, the proposed
application rate is 0.09-0.18 lb a.i./A/application.  The results of
this assessment represent the highest use of etoxazole, with two
applications.  Prior to this IR-4 new uses request, etoxazole was used
only once per season for all crops at rates of up to 0.18 lb a.i./A
(maximum rate for hops).  Thus, this action shows a doubling of the
seasonal application rate for the use on mint vs. the previously modeled
use on hops.  In addition to the use of the maximum rate, the effective
application rates for the degradates were derived by using the highest
observed percentage of each degradate in the aerobic soil metabolism
studies (corrected for the molecular weights of the degradates).  Of the
two degradates, which were observed in the aerobic soil metabolism
studies, R-8 was also observed in the anaerobic soil metabolism study. 
The formation of R-8 and R-13 in water appears unlikely because they
were not observed in the hydrolysis, aqueous photolysis and anaerobic
aquatic metabolism studies.

It was noted that the values of the surface waters concentrations of R-8
were very high (8.03 ppb for the peak and 4.08 ppb for the chronic
EDWCs), compared to the values obtained for the parent (6.07 ppb for the
peak and 0.618 ppb for the chronic EDWCs), despite the fact that the
“application rate” of R-8 was only a fraction (roughly ⅓) of the
application rate of etoxazole (0.0533 lb a.i./A for R-8 and 0.18 lb
a.i./A for the parent).  The higher EDWC values observed for R-8,
compared to etoxazole, are due to the high persistence of R-8 observed
in the aerobic soil metabolism studies (473 days for R-8 vs. 26.9 days
for etoxazole), and consequently also in the input values for the
aerobic aquatic metabolism. In addition, the KOC for R-8 is relatively
small (KOC = 103 mL/gOC), which translates in higher levels of the
chemical reaching the surface waters through runoff.  Finally, it was
assumed that R-8 does not undergo hydrolysis or photolysis, since no
data were available (vs. an aqueous photolysis rate for etoxazole of 34
days).

There is considerable uncertainty concerning the various degradates of
etoxazole (some of which appear to be relatively persistent).  The
absence of full environmental fate information about such degradates (in
particular about hydrolysis, aquatic metabolism and aqueous photolysis)
constitutes an uncertainty at this time; however, a conservative
approach was taken in this assessment in the absence of such data. There
is uncertainty in the role of the various competing dissipation and/or
degradation mechanisms of etoxazole.  In addition, a number of studies
have been deemed supplemental.

For this DWA, it has been assumed that at a given time, the maximum
amount of etoxazole has been applied to the field, and, at the same
time, certain amounts of R-8 and R-13 (determined by the percent of the
chemicals observed in the aerobic soil metabolism studies) are applied
by granular method (to simulate their formation on soil, and no drift). 
The EFED acknowledges that this method does not achieve mass balance,
that is, the amount of pesticide plus degradates applied exceeds the
maximum application rate of 0.18x2 lb a.i./A.  However, the Division
believes that the results obtained are suitable for a screening level
assessment.  The alternative approach of the total residues was not
utilized because the mobility characteristics of the degradates were
different than for the parent.

Despite these facts, the EFED believes that this assessment is
conservative.  A more definitive assessment could be performed, using
Tier II aquatic models PRZM/EXAMS, and if additional data are obtained
from the registrant about the degradates of concern.

The effects of water treatment on etoxazole and its degradates is
uncertain.  It is likely that primary treatment may reduce the levels of
etoxazole due to its tendency to bind.  However, there is no information
available at this time to determine the levels of reduction.APPENDIX

Nomenclature:

Applicant's Code	IUPAC Chemical Names

Etoxazole/Oxazole
(RS)-5-tert-butyl-2-[2-(2,6-difluorophenyl)4,5-dihydro-1,3-oxazole-4-yl]
phenetole

R-3			N-(2,6-Difluorobenzoyl)-4-tert-butyl-2-ethoxybenzamide

R-4		
N-(2,6-Difluorobenzoyl)-2-amino-2-(4-tert-butyl-2-ethoxyphenyl)ethanol	

R-7			2-amino-2-(4-tert-butyl-2-ethoxyphenyl)ethyl-2'
,6'-difluorobenzoate hydrochloride

R-8			2-amino-2-(4-tert-butyl-2-ethoxyphenyl)ethanol

R-11			2,6-Difluorobenzoic acid			

R-12			4-tert-Butyl-2-ethoxybenzoic acid			

R-13			4-(4-tert-Butyl-2-ethoxyphenyl)-2-(2,6-difluorophenyl)-oxazole

R-15			4-tert-Butyl-2-ethoxybenzamide

DBF			2,6-Difluorobenzamide

Registrant’s Code	CAS Name, available for etoxazole only

Etoxazole/Oxazole	2-(2,6-difluorophenyl)4-[4-(1,1-demethylethyl)
2-ethoxyphenyl-4,5-dihydrooxazole

Etoxazole

Output files from FIRST and SCIGROW:

                           SCIGROW

                          VERSION 2.3

            ENVIRONMENTAL FATE AND EFFECTS DIVISION

                 OFFICE OF PESTICIDE PROGRAMS

             U.S. ENVIRONMENTAL PROTECTION AGENCY

                        SCREENING MODEL

                FOR AQUATIC PESTICIDE EXPOSURE

 

 SciGrow version 2.3

 chemical:Etoxazole on Mint

 time is 10/21/2008  11:18:22

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.180           2.0           0.360      4.91E+03       20.5

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

 groundwater screening cond (ppb) =   3.46E-03 

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

 

                           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:R-8 on Mint

 time is 10/21/2008  11:20: 3

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.053           2.0           0.107      1.03E+02      377.0

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

 groundwater screening cond (ppb) =   7.42E-01 

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

 

                           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:R-13 on Mint

 time is 10/21/2008  11:21:37

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.054           2.0           0.107      1.37E+04      256.0

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

 groundwater screening cond (ppb) =   6.44E-04*

 *Estimated concentrations of chemicals with Koc values greater than
9995 ml/g

 are beyond the scope of the regression data used in SCI-GROW
development.

 If there are concerns for such chemicals, a higher tier groundwater
exposure

 assessment should be considered, regardless of the concentration
returned

 by SCI-GROW.

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

   RUN No.   1 FOR Etoxazole        ON   Mint          * INPUT VALUES * 

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

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

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

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

  0.180(  0.285)   2  21      68.0   75.0   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.) 

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

     26.90        2           0.00   34.00- 4216.00   53.80      53.12

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

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              6.072                      0.618

   RUN No.   2 FOR R-8              ON   Mint          * INPUT VALUES * 

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

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

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

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

  0.053(  0.105)   2  21     103.0    5.0   GRANUL( 0.0)  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.) 

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

    473.00        2          N/A      0.00-    0.00   946.00    946.00

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

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              8.032                      4.077

   RUN No.   1 FOR R-13             ON   Mint          * INPUT VALUES * 

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

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

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

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

  0.054(  0.106)   2  21     877.0  683.0   GRANUL( 0.0)  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.) 

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

    715.00        2           0.00    0.00-    0.00  ******    1430.00

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

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              1.626                      0.063

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

References:

Policy Establishing Current Versions of Exposure Models and
Responsibility for Model Maintenance (11/06/2002)

SCIGROW: Users Manual (11/01/2001, revised 08/23/2002)

FIRST Users Manual (08/01/2001)

FIRST: A Screening Model to Estimate Pesticide Concentrations in
Drinking Water (05/01/2001)

Guidance for Selecting Input Parameters in Modeling the Environmental
Fate and Transport of Pesticides, Version II (02/28/2002) 

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␱㜁Ĥ␸䠁Ĥ摧栫f᠀ SEQ CHAPTER \h \r 1 Use of the Index
Reservoir and Percent Crop Area in EFED Drinking Water Assessments
(12/01/1999)

Golf Course Adjustment Factors for Simulated Aquatic Exposure
Concentrations (06/01/2005)

  SEQ CHAPTER \h \r 1 Policy for Estimating Aqueous Concentrations from
Pesticides Labeled for Use on Rice (10/29/2002)

The Incorporation of Water Treatment Effects on Pesticide Removal and
Transformations in Food Quality Protection Act (FQPA) Drinking Water
Assessments  (10/25/2001)

Food and Agriculture Organization of the United Nations.  FAO PESTICIDE
DISPOSAL SERIES 8.  Assessing Soil Contamination: A Reference Manual. 
Appendix 2. Parameters of pesticides that influence processes in the
soil.  Editorial Group, FAO Information Division: Rome, 2000.   
HYPERLINK "http://www.fao.org/DOCREP/003/X2570E/X2570E00.htm" 
http://www.fao.org/DOCREP/003/X2570E/X2570E00.htm  

Ralf Nauen and Guy Smagghe.  2006. Mode of action of etoxazole. Pest
Management Science 62, 5, 379-382 (2006).  Abstract available on the web
at:   HYPERLINK
"http://www3.interscience.wiley.com/journal/112534516/abstract" 
http://www3.interscience.wiley.com/journal/112534516/abstract  

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