Document ID: EPA-HQ-OPP-2008-0361-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-04-08T04:00Z

SEQ CHAPTER \h \r 1 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

PC Code: 082583

DP Barcode: 357419

	

MEMORANDUM						     			

DATE:		October 17, 2008

SUBJECT:	Drinking Water Assessment for the Proposed Section 3
Registration of Cyhalofop-butyl for New Uses on Wild Rice Grown in
California 

TO:		Daniel Rosenblatt, Review Manager

		Sidney Jackson, Risk Manager Reviewer		

		Registration Division (7505P)

Office of Pesticide Programs

FROM:	Katrina White, Biologist

		Environmental Risk Branch II

		Environmental Fate and Effects Division (7507P)

THROUGH:	Tom Bailey, Branch Chief

		Nelson Thurman, Senior Fate Scientist

		Environmental Risk Branch II

		Environmental Fate and Effects Division (EFED) (7507P)

		Office of Pesticide Programs

The attachment to this memorandum presents the drinking water assessment
in response to a request from Dow Agrosciences LLC to register
cyhalofop-butyl (butyl (R)-2-[4-(4-cyano-2-
fluorophenoxy)phenoxy]propionate; PC Code 082583; CAS Number
122008-85-9)  for use as a postemergence herbicide to control grass
weeds in wild rice grown in California only.  The proposed registrations
would amend the label for the end-use product Clincher CA (EPA
Registration Number 62719-356; 29.6 % active ingredient (a.i.),
flowable) along with Clincher Technical (EPA Registration Number
62719-335) for use on rice to use on rice and wild rice.  

Questions related to this assessment can be directed to Dana Spatz,
(703) 305-6063 (  HYPERLINK "mailto:spatz.dana@epa.gov" 
spatz.dana@epa.gov ) or Katrina White, Ph.D., (703) 305-4536   HYPERLINK
"mailto:(white.katrina@epa.gov)"  (white.katrina@epa.gov) .

Attachment: 

Drinking Water Assessment for the Section 3 Registration of
Cyhalofop-butyl for Use on Wild Rice in California

Drinking Water Assessment for the Section 3 Registration of
Cyhalofop-butyl for Use on Wild Rice in California

October 17, 2008

Executive Summary

Proposed Use

Dow Agrosciences LLC is seeking Section 3 registration of
cyhalofop-butyl (butyl (R)-2-[4-(4-cyano-2-
fluorophenoxy)phenoxy]propionate; PC Code 082583; CAS Number
122008-85-9) for use as a postemergence herbicide to control grass weeds
in wild rice grown in California only.  The proposed registrations would
amend the label for the end-use product Clincher CA (EPA Registration
Number 62719-356; 29.6 % active ingredient (a.i.), flowable) along with
Clincher Technical (EPA Registration Number 62719-335) for use on rice
to use on rice and wild rice.  This assessment reports the drinking
water exposure assessment that has been conducted to support human
health risks assessment from the proposed new use. The proposed use on
wild rice would allow for a maximum single application of 0.28 lbs
active ingredient per acre (a.i./A) and a maximum seasonal application
rate of 0.46 lbs a.i./A, with a maximum of two applications that must be
applied at least ten days apart. Clincher CA may be applied via ground
spray or aerial spray from the 1 to 2 leaf stage up to 60 days before
harvest.  The timing allows for application to flooded or preflooded
(dry) paddies.  The proposed use for wild rice does not change the
application rate and, for the most part, should result in similar
exposures as the current approved use on rice.

Environmental Fate and Modeling Results for Drinking Water
Concentrations

The major degradates observed in environmental fate studies included
cyhalofop-acid, cyhalofop-amide, cyhalofop-diacid,
3-fluoro-4-(4-hydroxyphenoxy)benzoic acid (FHPBA), and
3-fluoro-4-(4-hydroxyphenoxy)benzonitrile (DP).  Previous drinking water
assessments estimated exposure to total residues of cyhalofop-butyl and
its major degradates.  In this assessment, exposure was estimated to
total residues of cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid
because these were the degradates of concern identified for drinking
water.  Since the last drinking water assessment was completed in 2001,
a standard model was developed to estimate surface water concentrations
from use of pesticides on rice, the Tier I Rice Model.  The model was
modified to account for possible aerobic aquatic degradation and aquatic
dissipation over time and used to estimate surface water concentrations
in water released from the rice paddy (tail water).  As in previous
assessments, estimated exposure concentrations (EECs) in ground water
were modeled using Tier I SCIGROW (version 2.3, dated July 29, 2003). 
The results of all analysis are presented in   REF _Ref210538157 \h  \*
MERGEFORMAT  

Table 1-1 .  Estimated exposure concentrations represent exposure to
total residues of cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid,
with assumptions that cyhalofop-butyl and cyhalofop-acid may be present
in the R or S form or as a mixture of the enantiomers.  Cyhalofop-butyl
and its degradates were not detected in surface water and drinking water
monitoring studies conducted in California where Rice is grown.

Tail water concentration estimates represent peak concentrations where
the paddy water is released, e.g., at the edge of the field.  The tail
water estimates allow for either degradation (an upper-bound exposure
estimate) or dissipation (a lower bound exposure estimate that accounts
for dissipation into other compartments not specifically addressed in
the Tier 1 model) to occur over time.  None of the estimates account for
expected dilution of paddy water in the receiving water body.  Peak
surface water EECs are approximately 2 - 11x ( 279 versus 137 and 25
ppb) the peak EECs reported in the previous drinking water assessments (
 REF _Ref211760007 \h  Table 3-3 ).  Chronic surface water EECs are
approximately 0.009 – 8x (0.13 – 21 versus 2.6 – 14.2 ppb) the
chronic EECs reported in the previous drinking water assessments (  REF
_Ref211760007 \h  Table 3-3 ).

Table   STYLEREF 1 \s  1 -  SEQ Table \* ARABIC \s 1  1 .Summary of the
highest predicted surface water and ground water concentrations for the
drinking water assessment on the use of cyhalofop-butyl on wild rice in
California

Drinking Water Source (Model Used)	Estimated Drinking Water
Concentration of Total Residues of cyhalofop-butyl, cyhalofop-acid, and
cyhalofop-diacid  (g/L)

	Acute or Peak	Annual Average (Noncancer Chronic)	Annual Average (Cancer
Chronic)

 Surface Tail Water (Tier I Rice Model with Aerobic Aquatic Degradation
only Considered)	279	21	21

 Surface Tail Water (Tier I Rice Model with Aquatic Dissipation
Considered)	12	0.13	0.13

Ground Water (SCI-GROW version 2.3)	0.152	0.152	0.152

Data Gaps and Uncertainties

The main uncertainties and data gaps in this risk assessment include the
following.

The model used to estimate surface water concentrations based on aerobic
aquatic degradation rates does not account for all the routes of
dissipation for the pesticide.  It does not account for all types of
pesticide degradation, mass transfer, volatilization, dilution, or other
dissipation processes.  The exposure estimates were therefore bracketed
using both dissipation rates and aerobic aquatic degradation rates.  The
EECs based on dissipation rates include uncertainties in measured
concentrations as a result of sampling and analytical errors (typical of
field studies in general), estimated concentrations in paddy water and
where paddy water is discharged  and should be used as bounding exposure
in conjunction with EECs based solely on aerobic aquatic degradation. 

Dilution of tail water into the receiving water body and downstream
dilution before it reaches drinking water intakes is expected to occur;
however, little information is available to estimate the degree of
dilution because that will depend on usage of the pesticide, the
weather, and other factors.  Therefore, the estimated surface water EECs
do not reflect this expected dilution.

The environmental chemistry method for the soil/sediment in the aquatic
field dissipation studies resulted in the butyl being hydrolyzed to the
acid.  Additionally, interference prevented analysis of the amide in
some circumstances.  The environmental chemistry method in water did not
have an independent laboratory evaluation.  Validated aquatic field
dissipation studies that are able to detect the parent compound and
major metabolites in both water and soil/sediment and that have
associated validated environmental chemistry methods are standard data
requirements.  The studies would reduce the uncertainty associated with
exposure to cyhalofop-butyl and its degradates in the natural
environment.  This is especially important because the aquatic
dissipation study results may be used to estimate surface water
concentrations and exposure to organisms.

No information on whether cyhalofop-butyl or cyhalofop-acid undergo
conversion to the S-enantiomer is available. The limited information
available on similar compounds in foreign soils indicate it is unlikely
(USEPA, 2008).  However, it is possible that it could racemize in water
and may behave differently with different microbial populations (Lee,
1989; Qin and Gan, 2007).

The sorption data for cyhalofop-butyl is not reliable and data on
sorption of the degradates are only available for a few soils.  As
sorption behavior of chemicals in different soils and sediments can
vary, estimated sorption may be off by a factor of three (Allen-king,
2002).  These measurements have a direct impact on estimated surface
water concentrations as this is the main input parameter for the Tier I
Rice model.  The lowest measured Kd value of all degradates was used to
estimate exposure, resulting in a conservative estimate of exposure. 
This is not expected to have a significant impact on the exposure
assessment.

Problem Formulation

This is a Tier I drinking water assessment that uses modeling and
available monitoring data to estimate the ground water and surface water
concentrations of pesticides 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.  

Analysis

Use Characterization

Cyhalofop-butyl is a registered active ingredient on three Section 3
labels and three Section 18 labels.  The Section 3 labels are for
similar uses on rice with the proposed amendment to add use on wild rice
in California only on the technical label and the Clincher CA label. The
proposed use on wild rice would allow for a maximum single application
of 0.28 lbs active ingredient per acre (a.i./A) and a maximum seasonal
application rate of 0.46 lbs a.i./A, with a maximum of two applications
that must be applied at least ten days apart (  REF _Ref210533526 \h 
Table 3-1 ). Clincher CA may be applied via ground spray or aerial spray
from the 1 to 2 leaf stage of rice up to 60 days before harvest.  The
timing allows for application to flooded or preflooded (dry) paddies. In
this assessment, application to flooded paddies was modeled as this was
expected to result in the highest modeled drinking water concentrations
(USEPA, 2001a).  Cyhalofop-butyl may be applied via ground or air. 
Additionally, a seven day holding period following the most recent
application is required before paddy water may be discharged.  The
proposed new uses will not result in increased application rates from
previously approved uses.

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  1 .  Proposed and
previously registered uses on the Clincher CA label (EPA Registration
Number 62719-356) 

Crop/ Use	Recommended Single Application Rates	Maximum Single
Application Rate1	Maximum Seasonal Application Rate2	Application
Interval 

	oz./A	oz./A	lbs. a.i./A	oz./A	lbs. a.i./A	 days

Rice and Wild Rice	13 - 15	15	0.28	25	0.46	10

Abbreviations:  oz./A refers to the total fluid ounces of product (29.6%
a.i.) per acre as specified on the label; lbs.a.i./A =pounds active
ingredient per acre as converted from oz/A;  A=Acre; a.i.=active
ingredient

Calculated as Maximum single application rate (ounces per A) x 0.238 lbs
a.i. per gallon/128 oz per gallon (from conversion table on label).

Calculated as Maximum seasonal application rate (ounces per A) x 0.238
lbs a.i. per gallon/128 oz per gallon (from conversion table on label).

The proposed new uses include the use footprint of the previously
registered uses and expands it to some counties in Northern California. 
Wild rice was grown on 11,780 acres in California in 1997 (USDA, 2000). 
California's wild rice is grown in three distinct climatic regions: the
rice-producing areas in the Sacramento Valley; areas surrounding Clear
Lake in Lake County; and the mountain valleys in north-eastern
California.  In 2008, the counties where Rice was grown included Butte,
Colusa, Fresno, Glenn, Merced, Placer, Sacramento, San Joaquin,
Stanislaus, Sutter, Tehama, Yolo, and Yuba based on counties with
programs listed by the United States Department of Agriculture Risk
Management Agency (  REF _Ref210532591 \h  Figure 3-1 ).   In 2008, the
counties where wild rice was grown included Lassen, Modoc, Shasta,
Sutter, and Yolo (  REF _Ref210532575 \h  Figure 3-2 ). The proposed use
will expand use of cyhalofop-butyl to north eastern counties of Lassen,
Modoc, and Shasta.  In California, seeding is generally done in the
spring, except in some of the higher elevations, where planting may also
occur in the fall (Zep et al., 1996).  In the Sacramento Valley, annual
reseeding in the spring is required because the paddies do not remain
moist over the winter (Zep et al., 1996).  Thus, in most circumstances
cyhalofop-butyl will be applied to wild rice paddies in the spring;
however, the proposed use could also result in some applications of
cyhalofop-butyl in the fall at high elevations.  

 

Figure   STYLEREF 1 \s  3 -  SEQ Figure \* ARABIC \s 1  1 .  Counties
with rice programs in 2008  

(From USDA 2008 County Crop Progams available at:    HYPERLINK
"http://www.rma.usda.gov/data/cropprograms.html" 
http://www.rma.usda.gov/data/cropprograms.html , accessed September 24,
2008).

 

Figure   STYLEREF 1 \s  3 -  SEQ Figure \* ARABIC \s 1  2 .  Counties
with wild rice programs in 2008  

(From USDA 2008 County Crop Progams available at:    HYPERLINK
"http://www.rma.usda.gov/data/cropprograms.html" 
http://www.rma.usda.gov/data/cropprograms.html , accessed September 24,
2008).

Environmental Fate and Transport Characterization

A complete discussion of the physicochemical properties and
environmental fate information is available in   REF _Ref211765007 \h 
\* MERGEFORMAT  Appendix A .  Review of Subdivision N guideline studies
on the fate characteristics of cyhalofop-butyl (butyl) indicate that the
parent is degraded to cyhalofop-acid by biologically-mediated hydrolysis
in less than a day (  REF _Ref211765437 \h  Table A 4 ). Further
degradation leads mainly to cyhalofop-amide and to cyhalofop-diacid.    

Hydrolysis and photolysis are much slower (half-lives ranged from 25
days to stable at pH 5 and 7) compared to biological degradation at
neutral to acidic pH (  REF _Ref211765437 \h  Table A 4 ).  Abiotic
hydrolysis is more rapid at pH 9 (half-life = 2 days).

The major degradates (made up greater than 10% applied parent
equivalents) in aerobic studies include cyhalofop-acid (acid),
cyhalofop-amide (amide), and cyhalofop-diacid (diacid), maximum percent
applied parent equivalents were 98.7%, 44.5%, and 86.5% respectively. 
Two degradates were major degradates under certain circumstances. 
3-fluoro-4-(4-hydroxyphenoxy)benzoic acid (FHPBA) was a maximum of 20.3%
applied parent equivalents in an anaerobic aquatic metabolism study
(MRID 45000517) and (2R)-2-(4-hydroxyphenoxy)propanoic acid (DP or FCPP)
was a maximum of 12.0% applied parent equivalents in a photodegradation
study.  Minor degradates that made up less than 10% applied parent
equivalents include (2R)-2-(4-hydroxyphenoxy)propanoic acid (HPPA) and
(3-fluoro-4-hydroxybenzonitrile) (FHB).  

The major degradates of cyhalofop-butyl (acid, amide, diacid) are
generally water-soluble and weakly acidic.  The pKa of cyhalofop-acid is
3.80, which makes it an anion at pH 7, and its solubility is 251 mg/L at
pH 7 (  REF _Ref211765346 \h  Table A 2 ).  Reliable sorption data on
cyhalofop-butyl is not available.  Sorption of cyhalofop-acid in the
aquatic environment was not well predicted by organic carbon and Kd
values ranged from 0.46 – 6.2 L/kg.  The Kd values for cyhalofop-amide
ranged from 0.3 – 0.47 L/kg and the Kd for cyhalofop-diacid ranged
from 5.7 – 10.4 L/kg.  Not enough data was available to evaluate the
relationship of sorption to percent OC for the diacid and amide.  

The physicochemical properties indicate that the degradates will have
little tendency to volatilize, or to sorb to soil (  REF _Ref211765346
\h  Table A 2  and   REF _Ref211765699 \h  Table A 5 ).  The degradates
will be quite mobile due to the low Kd values.  Cyhalofop-butyl residues
will likely degrade in the water column, and be substantially
mineralized to carbon dioxide.   Residues in paddy water from California
and Arkansas field studies dissipated to below detectable levels after
28 days (MRID 45000520).  

Cyhalofop-butyl and cyhalofop-acid may exist as an R or S enantiomer. 
The active ingredient registered is in the R form; however, conversion
to the S enantiomer may occur in the natural environment. 

Drinking Water Exposure Assessment

Previous Assessments

  REF _Ref210535100 \h  Table 3-2  summarizes the previous drinking
water assessments completed for use of cyhalofop-butyl on rice.  The
most recent assessment was reported in a combined ecological risk
assessment with drinking water numbers included and was completed on
September 27, 2001 (D275810) for a Section 3 label for the use of
cyhalofop-butyl on rice (USEPA, 2001a).  The use examined was
essentially the same as reviewed in this assessment, except that uses
were not restricted to use in California and the proposed label allows
for use on wild rice.  Exposure to total residues, specific degradates
not specified, was evaluated.  The assessment was completed before the
Tier I Rice Model was developed to estimate surface water concentrations
that are used in risk assessment.  Instead a hypothetical rice paddy was
assumed and surface water concentrations were estimated after discharge
of the rice paddy water to a reservoir where 2x dilution was assumed.   
REF _Ref211760007 \h  Table 3-3  summarizes the EECs from the previous
drinking water assessments.

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  2 .  Summary of
uses and modeling methods used in previous drinking water assessments
for cyhalofop-butyl

DP Barcode

Date

	Chemical in Assessment	Use Site	Uses Assessed	Model Used

D275810

8/10/2001	Total Residues (specific degradates included not stated)	Rice
Paddies	210g/ha followed by 310g/ha, 10 day interval	Hypothetical rice
paddy followed by discharge to Index Reservoir (2X dilution) 

D275810

9/27/2001	Total Residues (specific degradates included not stated)	Rice
Paddies	Flooded paddies 0.463 lbs a.i./A, or split into equal
applications of 0.185 and 0.278 lbs a.i./A with a 10-day interval
Hypothetical rice paddy after growing season with discharge to Index
Reservoir (2X dilution) 

SCI-GROW

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  3 .  Summary of
the drinking water EECs from the previous drinking water assessments.

Drinking Water Source (Model Used)	Estimated Drinking Water
Concentration of 

g/L)

	Acute or Peak	Chronic

Surface Water – Califronia (Wet Seeded)	36	3.7

Surface Water - Gulf Coast (Wet Seeded)	137	14.2

Surface Water – Mississippi Valley (Dry Seeded)	119	12.4

Surface Water – Release day 79	25	2.6

Ground Water (SCI-GROW version 2.3)	0.16	0.16

Information taken from Page 11 and 44 of Section 3 Registration for
Cyhalofop-butyl on Rice (D275810; Memo to J. Miller from W. Eckel and
R.W. Felthousen, dated 9/27/2001)

Since the previous assessments were completed a surface water monitoring
study (MRID 445573201) and a drinking water monitoring study (MRID
47380601) were submitted to the agency.

Surface Water

Tier I Rice Model and Surface Water Modeling

Concentration of total toxic residues in surface water were estimated
using a modified version of the standard Tier I Rice Model that accounts
for possible degradation or dissipation in the paddy water.

The original Tier I Rice Model relies on an equilibrium partitioning
concept to provide high-end screening estimates of EECs resulting from
application of pesticides to rice paddies.  When a pesticide is applied
to a rice paddy, the model assumes that it will instantaneously
partition between a water phase and a sediment phase.  The Tier I Rice
Model was calibrated to generate estimates that are similar to or
greater than dissolved concentrations measured within rice paddies and
in discharged paddy water.  The calibration involved determination of
the sediment interaction depth by calibrating the model to maximum
residues measured in paddy water in dissipation studies.  The model does
not account for pesticide degradation, mass transfer between the aqueous
phase and the sediment, volatilization, dilution, or other dissipation
processes. Pesticide degradation, mass transfer, volatilization,
dilution and other dissipation processes may have occurred in the
datasets used to calibrate the model but probably had little effect on
the calibration because the calibration was based on the maximum
measured residues. The model was not evaluated or calibrated for
concentrations measured in sediment and does not account for residues
bound to suspended sediment.  Guidance for using the Tier I Rice Model
may be found on the U.S. Environmental Protection Agency (EPA) Water
Models web-page (USEPA, 2007).

The Tier I Rice Model was provisionally modified to account for
degradation and dissipation in the paddy water during the seven day
holding period required by the label prior to when water is released
from the field.  Rates of dissipation were based on dissipation that
occurred in aquatic dissipation studies and degradation was based on
aerobic aquatic degradation rates.   Assumptions of the Tier I Rice
Model, other than stability to dissipation or degradation, apply to the
modified model.  

Due to a range of environmental variables and other factors, the Tier I
Rice Model is expected to generate high-end EECs that are likely to
exceed peak measured concentrations of pesticides in water bodies
downstream of rice paddies.  Also, the EECs are expected to be greater
than what would actually occur at drinking water intakes downstream of
rice paddies in California and inland areas of the Southeastern U.S.,
where dilution is expected to occur.  

Model Inputs and Estimated Exposure Concentrations in Surface Water

The residues of concern identified for drinking water concern were
cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid.  Thus, aquatic
exposure was estimated for total residues of cyhalofop-butyl,
cyhalofop-acid, and cyhalofop-diacid using a modified version of the
Tier I Rice Model to allow for aerobic degradation and aquatic
dissipation.  The models are described below and summarized in   REF
_Ref211997789 \h  Table 3-4 .  Exposure was only modeled for the
applications to wet paddies because modeled concentrations for dry
applications would result in lower concentrations in water (USEPA
2001a).  

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  4 .  Summary of
modeling used to estimate surface water concentrations of total residues
of cyhalofop-butyl and its degradates

Model	Characterization	Class of Exposure Estimate

Tier I Rice Model with Aerobic Degradation	Estimates exposure over time
allowing for aerobic aquatic degradation in the water column for both
paddy water and tail water	Upper bound on drinking water exposure
because it doesn’t account for other routes of dissipation and
doesn’t take into account downstream dilution 

Tier I Rice Model with Aquatic Dissipation	Estimates exposure over time
allowing for aquatic dissipation including sorption, abiotic
degradation, metabolism, and plant uptake for both paddy water and tail
water	Indirectly accounts for other routes of dissipation with
uncertainties in terms of how well the field study represents actual
conditions in the range of CA sites; still likely to be upper bound
because of downstream dilution 

Tier I Rice Model

The equation of the Tier I Rice Model is:

Cw = mai’ / (0.00105 + 0.00013 x Kd)

Where Cw is the paddy water concentration (ppb), mai’ is the
application rate (kg/hectare) and Kd is the soil-water distribution
coefficient in L/kg.  

Modified Tier I Rice Model with Degradation or Dissipation Rates

To account for possible loss of total residues from water, surface water
concentrations were estimated using aerobic aquatic degradation rates
and aquatic dissipation rates.  

Tier I Rice Model Modified with Aerobic Aquatic Degradation Rates

The EECs based on aerobic aquatic degradation rates allow for aerobic
degradation to occur and no other losses are accounted for.  These EECs
reflect conservative exposure estimates and estimates exposure over
time.

Tier I Rice Model Modified with Aquatic Dissipation Rates

The EECs based on aquatic dissipation rates take into account additional
routes of dissipation not included in the aquatic degradation, to the
extent that such routes occurred during the field study.  However,
because the study also reflects uncertainties in measured concentrations
as a result of sampling and analytical errors (typical of field studies
in general), estimated concentrations in paddy water and where paddy
water is discharged should be used as bounding exposure in conjunction
with EECs based solely on aerobic aquatic degradation. 

The concentration in water for the modified Tier I Rice Model was based
on the following equation:

Cw, t = Cw, 0 e(-kt)

Where

Cw, t 	= the concentration in water at time, t

Cw, 0 	= the concentration in water at application or time of zero
(calculated using the Tier I 	Rice Model)

e 	= base of natural logarithm

k 	= first-order rate constant of degradation or dissipation (1/days)

t 	= time after application (days)

When two applications were modeled, the initial concentration in the
water after each application was estimated using the Tier I Rice model,
degradation/dissipation was modeled from the date of application for
every day after for a specified time.  Concentrations in water from the
first and second applications were added to determine the total
concentration in water over time for each day.  Acute concentrations
were reported at the maximum concentration for the given scenario.  The
exposure calculations began eight days after the second application for
tail water concentrations because a seven day water holding time is
required on the label.  Chronic concentrations were taken as the average
daily concentration over 365 days.

Dilution of Tail Water

Tail water is defined as water released from the rice paddy.  These
concentrations may be seen briefly where the paddy water is released. 
Actual EECs will be lower in the receiving water body where dilution
will occur as the tail water mixes with waters it is released into and
the water moves away from the point of release.  The concentrations
reported do not reflect any dilution of the tail water.  Dilution and
degradation/dissipation are expected to reduce concentrations in water
prior to their movement to drinking water intakes.  The extent of this
reduction in concentrations depends on 1) the length of time the
compound is in the water, 2) the distance the water will travel before
the drinking water intake, 3) the amount of dilution and 4) whether the
water it is mixed with also carries residues of cyhalofop-butyl.  These
factors will vary and are uncertain.

The input parameters for the Tier I rice model and modified version of
the Tier I Rice model are in   REF _Ref210126315 \h  \* MERGEFORMAT 
Table 3-5 .    REF _Ref210819105 \h  \* MERGEFORMAT  Appendix C 
contains the data used to calculate input values and the calculations
from the model.

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  5 .  Summary of
input parameters used to estimate surface water concentrations for total
residues of cyhalofop-butyl, acid, amide, and diacid 

Fate Property	Value	MRID or Source, Comments

Soil-Water Distribution Coefficient, Kd 	0.463 L/kg	MRID 45014714,
45000519; Although the coefficient of variation (standard
deviation/mean) was lower for KOC values than Kd values for
cyhalofop-acid (  REF _Ref211765109 \h  \* MERGEFORMAT  Table C 2 ),
organic carbon was not a good predictor of sorption (  REF _Ref211765872
\h  \* MERGEFORMAT  Figure C 1 ).  Data for cyhalofop-acid was evaluated
because it had the most robust dataset.  Surface water concentrations
were estimated using the lowest Kd values measured for cyhalofop-acid
and other degradates.  Kd values ranged from 0.463 – 10.37 L/kg (  REF
_Ref211765109 \h  \* MERGEFORMAT  Table C 2 ).

Aerobic Aquatic Metabolism 	42 days

k = 0.0384 1/day	MRID 45000518 and 45000526; Values represent the upper
90th percentile confidence bound of the mean first-order half-lives
(nonlinear fit) of total residues measured in water and sediment for
cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid (  REF
_Ref211766107 \h  \* MERGEFORMAT  Table C 3 ).  The upper 90th
percentile bound of the mean half-lives is 58 days if bound/unextracted
residues were included in the calculation (  REF _Ref211997928 \h  \*
MERGEFORMAT  Table C 4 ).  The value with the bound residues was not
used because exposure to bound residues was not expected to occur and
the estimated value is already sufficiently conservative.

Field Dissipation Studies	2.72 days

k = 0.3169 1/day

	MRID 45000520; Values represent the upper 90th percentile confidence
bound on the mean dissipation half-life (linear/natural log fit) of
total residues of cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid
measured in water in aquatic dissipations studies completed in Arkansas
and California.  Applications were applied to both dry and flooded plots
that were either cropped or bare ground.  Dissipation rates could be
calculated for total residues measured in both soil and water; however,
residues were not reported in percent applied equivalents and soil
residues in the California plot were only detected in two samples and
residues in the Arkansas plot were all less than 50 ng/g after the first
day of application.  

Peak surface water EECs for the tail water ranged from 12 –  279 µg/L
for total residues.  The annual average concentrations ranged from 0.09
– 21 µg/L.    REF _Ref210547689 \h  Table 3-6  summarizes all
predicted surface water EECs and surface water EECs over time are shown
in   REF _Ref210550755 \h  Figure 3-3 .  As tail water mixes with the
water it is released into and moves toward drinking water intakes it
will be diluted with water from other sources.  This dilution was not
considered in the estimated drinking water concentrations.

Figure   STYLEREF 1 \s  3 -  SEQ Figure \* ARABIC \s 1  3 .  Estimated
surface water concentrations of total residues cyhalofop-butyl, acid,
and diacid predicted over time from the use of cyhalofop-butyl on wild
rice.  A second application occurred 10 days after the first.

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  6 .  Summary of
estimated environmental concentrations (EECs) of total residues of
cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid in tail water from
the use of cyhalofop-butyl on wild rice

Use - Type of Exposure

	Model	App. Rate (kg/ha)1	Concentration of Total Residues (µg/L)

	Peak	Annual Average3

Two Applications – 

Tail Water	Tier I Rice Model with Degradation Considered	0.31 followed
by 0.212	279	20

Two Applications – 

Tail Water	Tier I Rice Model with Dissipation Considered 	0.31 followed
by 0.212	12	0.09

Abbreviations:  App. = application; ha=hectare; A=acre; a.i.=active
ingredient

Calculated from lbs a.i./A using the following equation:  (lbs a.i./A) x
(1 kg/2.205 lbs) x (2.47 A/hectare)=kg a.i./A.  The values reflect 0.28
lbs a.i./A and 0.18 lbs a.i./A.

In this scenario, there were two applications with an application
interval of ten day based on the minimum application interval specified
on the label.

This was calculated as the average concentration from seven days after
the second application through 365 days (from day 18 through 383 days).

Ground Water

The regression model SCI-GROW2 (v. 2.3) was used to estimate the
concentration of cyhalofop-butyl in ground water.  SCI-GROW estimated
the concentration of cyhalofop-butyl in shallow ground water sources to
be 0.152 (g/L using the average aerobic soil half-live of total
residues.  Input parameters for SCI-GROW are presented in   REF
_Ref204751751 \h  Table 3-7  and the output files in   REF _Ref210819105
\h  \* MERGEFORMAT  Appendix C .

SCIGROW (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 organic-carbon water partition coefficient (KOC). 
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. 

Table   STYLEREF 1 \s  3 -  SEQ Table \* ARABIC \s 1  7 .  Input values
used for modeling groundwater concentrations of cyhalofop-butyl and its
degradates using SCI-GROW2

Model Input Parameter	Input Value and Unit	Source/Comments

Aerobic Soil Metabolism Half-life (days)	Without soil residues:

Half-life = 21 days	MRID 45014715, 45000515.  Average of six half-lives
for cyhalofop-butyl, cyhalofop-acid, and cyhalofop-diacid (see   REF
_Ref211766051 \h  \* MERGEFORMAT  Table C 5 ).

Organic-Carbon Normalized Partition Coefficient  Koc	35 (mL/g)

	MRID 45014714; The lowest KOC value was used because there was greater
than a three fold difference in values.  The lowest KOC was the KOC for
the diacid in Speyer 2.2, a loamy sand soil from Germany, see   REF
_Ref211765109 \h  \* MERGEFORMAT  Table C 2 .

Application Rate	0.23lbs a.i./A

	Maximum seasonal application rate/2 from proposed label

Maximum No. of Applications/Year	2	Proposed label

Monitoring

Monitoring data provide different kinds of information than modeling
estimates.  For example, monitoring data consist of actual information
from the field, reflecting current use pattern and usually
underestimating frequency of occurrence.  Monitoring data does not
always include peak values, and inputs for monitoring cannot be adjusted
as modeled ones can.  In addition, monitoring is often conducted for
purposes other than characterizing exposure from a particular pesticide,
and as a consequence is used to complement modeling rather than to
refine it.  In general, a useful interpretation of monitoring values
requires in-depth assessment of the data, which is beyond the scope of a
Tier I assessment.  

Surface Water Monitoring Study

Dow AgroSciences submitted a study entitled “Surface water monitoring
of cyhalofop-butyl in a California rice growing region in 2001,”  MRID
45573201.  Surface water monitoring was conducted weekly on Thursdays
from May 24 to August 9, 2001.  Application began on May 4, about three
weeks before the monitoring began.  Samples were collected from the
Cross Canal where it enters the Feather River at State Highway 99.  Dow
states that this sampling site integrates drainage from the five-county
area where application of cyhalofop-butyl was allowed under the Section
18 registration (155,000 acres in Hydrologic Catalog Unit number
180201109).  

According to California Pesticide Use Reports 788 lbs of cyhalofop-butyl
was applied to 2,688 acres of rice in the monitored watershed
(Sacramento River) in 2001.  Results were initially reported for
cyhalofop-butyl and cyhalofop-acid with detection limits of 0.5 ppb. 
Storage stability studies were submitted; however, the laboratory method
was not independently evaluated.  The water samples were re-analyzed for
cyhalofop-amide and cyhalofop-diacid.  No detections were reported.

It is difficult to interpret the results of the study.  While it is
encouraging that no parent or metabolites were detected at 0.5 ppb, the
chronic drinking water level of comparison is lower, estimated to be
0.015 ppb in 2001 (USEPA, 2001c).  Additionally, 1) we do not know when
paddy water was released in relation to when surface water samples were
collected, 2) the one week sampling interval was a long period and could
easily miss residues in water, and 3) the environmental chemistry method
did not have an independent laboratory validation as required.  Control
samples were collected from an area where cyhalofop-butyl was not used
and fortified with cyhalofop-butyl in the lab.  The data tables in the
study report are difficult to read but recoveries appear to range from
8-96%, with stored samples yielding lower recoveries.  This indicates
that a large percentage of residues in the water samples may have been
lost due the analytical method or during storage.  The analytical method
report indicates a much higher recovery rate with average recoveries
ranging from 88 – 107% for the different compounds.  Finally,
monitoring should begin closer in time to the start of chemical
application, rather than the 20-day lag in the study.

Drinking Water Monitoring Study

A drinking water monitoring study was also submitted (MRID 47380601) and
is still being reviewed by the Agency.  According to the report,
approximately 4,250 kg of cyhalofop-butyl was applied in California
(Suter, Yuba, Placer, Glenn, Colusa, Sacramento, and Butte counties)
between May 5, 2002 and July 21, 2002 under a Section 18 Specific
Exemption.  Water samples were collected on a semi-weekly basis from the
drinking water facility intakes of Sacramento and West Sacramento
facilities from April 30 to July 18 2002.  Cyhalofop-butyl,
cyhalofop-acid, cyhalofop-amide, and cyhalofop-diacid residues were not
found at the limit of quantitation (0.1 µg/L) in any drinking water
samples.  Cyhalofop-butyl was detected in one sample near the limit of
detection of 0.04 µg/L at the West Sacramento facility.    

While it is encouraging that no parent or metabolites were detected at
0.1 ppb, it is difficult to interpret the results of the study because
the environmental chemistry method did not have an independent
laboratory validation as required.  Control samples included matrix
spikes (deionized water spiked with cyhalofop-butyl) with recoveries of
cyhalofop-butyl ranging from 78-102%.  Assuming the method was a valid
method and significant loss did not occur with storage and transport,
this study indicates that when approximately 4,250 kg of cyhalofop-butyl
is applied in the Sacramento Valley area on rice, drinking water
exposure to Sacramento residents getting water from the two facilities
monitored will be less than 0.1 µg/L.  It does not provide any
information about drinking water intakes upstream of the Sacramento and
West Sacramento areas or for when applications exceed 4,250 kg in a
season.  

Other Monitoring Results

The following databases and sources were searched for monitoring
information on cyhalofop-butyl:

The United States Environmental Protection Agency (USEPA) STORET
Database (  HYPERLINK "http://www.epa.gov/storet/dbtop.html" 
http://www.epa.gov/storet/dbtop.html )

The United States Geological Survey (USGS) National Water-Quality
Assessment (NAWQA) Program Data Warehouse (  HYPERLINK
"http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567" 
http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567 ) 

The USGS National Stream Quality Accounting Network (NASQAN) program
(http://water.usgs.gov/nasqan/)

Sampling for Pesticides Residues in California Well Water Cumulative
Report; EEH03-08; December 2003
(http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/eh0308.pdf) 

California Department of Pesticide Regulation (DPR) Surface Water
Database (  HYPERLINK
"http://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm" 
http://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm )

 No monitoring information was found.

Drinking Water Treatment

Little information is available on the effect of drinking water
treatment on cyhalofop-butyl and its degradates.  The softening of
drinking water will generally result in an increase in pH and could
result in hydrolysis of the butyl to the acid.  

Literature Cited

Allen-King, R. M., P. Grathwohl, and W. P. Ball.  2002.  New modeling
paradigms for the sorption of hydrophobic organic chemicals to
heterogeneous carbonaceous matter in soils, sediments, and rocks. 
Advances in Water Resources 25:  985-1016.

Blasioli, S., I. Braschi, M. V. Pinna, A. Pusino, and C. E. Gessa. 
2008.  Effect of undesalted dissolved organic matter from composts on
persistence, adsorption, and mobility of cyhalofop herbicide in soils. 
Journal of Agricultural Food Chemistry 56:  4102-4111.

Corbin, M.; W. Eckel; M. Ruhman; D. Spatz;  N. Thurman; R. Gangaraju; T.
Kuchnicki; R. Mathew; and I. Nicholson.  2006.  NAFTA Guidance Document
for Conducting Terrestrial Field Dissipation Studies.    HYPERLINK
"http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.
htm" 
http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.h
tm  (accessed March 26, 2008).

Food and Agriculture Organization of the United Nations (FAO).  Appendix
2.  Parameters of pesticides that influence processes in the soil.  In
FAO Pesticide Disposal Series 8.  Assessing Soil Contamination. A
Reference Manual.  FAO Information Division Editorial Group. Rome, 2000.
   HYPERLINK "http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm" 
http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm  (accessed March 27,
2008).

Lee, P.W. 1989. Hydrolysis of [Chlorophenyl-14C] DPX-GB800 in buffer
solutions of pH 5, 7, and 9. Unpublished study submitted by E.I. du Pont
de Nemours and Co., Inc., Wilmington, DE. Laboratory Project ID
AMR-1185-88. MRID 40999303.

Parveen, S., T. Kohguchi, H. Shimazawa, N. Nakagoshi.  2005.  Measuring
of some selected herbicides in paddy surface water in the Saijo Basin,
Western Japan.  Agron. Sustain. Dev. 25:  55-61.  

Pinna, M.V., I. Braschi, S. Blasioli, C.E. Gessa, and A. Pusino.  2008. 
Hydrolysis and adsorption of cyhalofop-butyl and Cyhalofop-acid on soil
colloids.  Journal of Agricultural and Food Chemistry 56:  5273-5277.  

Qin, S, and J. Gan.  2007.  Abiotic enantiomerization of permethrin and
cypermethrin:  effects of organic solvents.  J. Agric. Food Chem. 55: 
5734-5739.

Tu, M.; C. Hurd; and J. M. Randall.  2001.  Weed Control Methods
Handbook:  Tools & Techniques for Use in Natural Areas, The Nature
Conservancy.    HYPERLINK
"http://tncweeds.ucdavis.edu/products/handbook/methods-handbook.pdf" 
http://tncweeds.ucdavis.edu/products/handbook/methods-handbook.pdf 
(accessed May 5, 2008).  

United States Department of Agriculture (USDA).  2000.  Crop Profile for
Wild Rice in California.  January, 2000.    HYPERLINK
"http://www.ipmcenters.org/CropProfiles/docs/cawildrice.pdf" 
http://www.ipmcenters.org/CropProfiles/docs/cawildrice.pdf  (accessed
September 24, 2008).

United States Environmental Protection Agency (USEPA). 2001a.  Section 3
Registration for Cyhalofop-butyl on Rice.  Memo to J. Miller from W.
Eckel and R. Felthousen; DP Barcode D275810; September 27, 2001.  U.S.
Environmental Protection Agency, Office of Prevention, Pesticides and
Toxic Substances, Office of Pesticide Programs, Environmental Fate and
Effects Division, Washington, DC.  

U.S. EPA, 2001b.  Product Chemistry Review of Cyhalofop-butyl Technical,
Memo to J. Miller from S. Mathur; DP Barcode 269915; April 26, 2001. 
U.S. Environmental Protection Agency, Office of Prevention, Pesticides
and Toxic Substances, Office of Pesticide Programs, Washington, DC.  

USEPA 2001c.  Cyhalofop-butyl:  Surface Water Monitoring in California,
2001.  Memo to J. Miller from W. Eckel; DP Barcode 280411; February 20,
2002.  U.S. Environmental Protection Agency, Office of Prevention,
Pesticides and Toxic Substances, Office of Pesticide Programs,
Environmental Fate and Effects Division, Washington, DC.  

USEPA 2007.  Guidance for Tier I Estimation of Aqueous Pesticide
Concentrations in Rice Paddies.  Memo from S. Bradbury to Environmental
Fate and Effects Division; May 8, 2007.  U.S. Environmental Protection
Agency, Office of Prevention, Pesticides and Toxic Substances, Office of
Pesticide Programs, Environmental Fate and Effects Division, Washington,
DC.  Available at   HYPERLINK
"http://www.epa.gov/oppefed1/models/water/#rice" 
http://www.epa.gov/oppefed1/models/water/#rice  (accessed September 29,
2008).

USEPA 2008.  Ecological Risk Assessment Addressing the Proposed
Registration of Fluazifop-p-butyl for New Uses on Peanuts and Dry Beans
and Amended Uses on Soybeans.  Memo from R. Dean to J. Miller; DP
Barcode 347516; August 28, 2008.  U.S. Environmental Protection Agency,
Office of Prevention, Pesticides and Toxic Substances, Office of
Pesticide Programs, Environmental Fate and Effects Division, Washington,
DC.  

Wood, A.  2007.  Compendium of Pesticide Common Names.  Last updated on
Feb. 8, 2007.  Online at:   HYPERLINK
"http://www.alanwood.net/pesticides/index.html" 
http://www.alanwood.net/pesticides/index.html 

Environmental Fate MRID Studies

MRID Number	Study Title

45000233	Rick, D.; Dittenber, D.; Markham, D. (1999) The
Bioconcentration of DE-537 N-Butyl Ester by the Rainbow Trout,
Oncorhynchus mykiss Walbaum: Lab Project Number: 991077. Unpublished
study prepared by The Dow Chemical Company. 91 p. 

45000510	Shimada, N. (1995) XRD-537 BE Hydrolysis Study: Lab Project
Number: GHF-R-299: DPC/AE-1529-2G: AE-1529-2F. Unpublished study
prepared by Daiichi Pure Chemicals Co., Ltd. 103 p. 

45000511	Cook, W. (1999) Hydrolysis of Cyhalofop-butyl at pH 5, 7, and
9: Lab Project Number: 990053. Unpublished study prepared by Dow
Agrosciences LLC. 38 p. 

45000512	Ohdake, J. (1992) XDE-537 N-Butyl Ester; Stability Under
UV-Light (254nm): Lab Project Number: GHF-P 1184: 91-607-F. Unpublished
study prepared by DowElanco Japan Ltd. 17 p. 

45000513	Ridge, M. (1997) Photodegradation of (carbon 14)-DE-537 on a
Soil Surface: Lab Project Number: GHE-P-6158: 295/67. Unpublished study
prepared by Covance Labs. 82 p. {OPPTS 835.2410} 

45000514	Kennard, L. (1999) Photodegradation of (carbon 14)
Cyhalofop-butyl on Aerobic Soil by Natural Sunlight: Lab Project Number:
ENV98069. Unpublished study prepared by Dow AgroSciences LLC. 138 p. 

45000515	Yoder, R. (1999) Aerobic Soil Degradation of (carbon
14)-Cyhalofop-Butyl in Two U.S. Soils: Lab Project Number: ENV98060.
Unpublished study prepared by Dow AgroSciences LLC. 64 p. 

45000515	Yoder, R. (1999) Aerobic Soil Degradation of (carbon
14)-Cyhalofop-Butyl in Two U.S. Soils: Lab Project Number: ENV98060.
Unpublished study prepared by Dow AgroSciences LLC. 64 p. 

45000516	Cook, W. (1999) Aerobic Soil Degradation of
(carbon-14)-Cyhalofop-butyl and its Degradates at 10 and 20(degrees
centigrade): Lab Project Number: ENV98071. Unpublished study prepared by
Dow AgroSciences LLC. 76 p. 

45000517	Batzer, F. (1999) Anaerobic Metabolism of Cyhalofop-butyl: Lab
Project Number: ENV98055. Unpublished study prepared by Dow AgroSciences
LLC. 138 p. 

45000518	Smith, J.; Graper, L.; Smith, K. (1999) Aerobic Aquatic
Metabolism of (carbon 14)-Cyhalofop-butyl: Lab Project Number: ENV98034.
Unpublished study prepared by Dow AgroSciences LLC. 72 p. 

45000519	Heim, L.; Meitl, T. (1999) Batch Equilibrium Sorption of
(carbon 14)-Cyhalofop-butyl and (carbon 14)-Cyhalofop-acid on Sterile
Soils: Lab Project Number: 990038. Unpublished study prepared by Dow
AgroSciences LLC. 249 p. 

45000520	Knuteson, J.; Foster, D. (1999) Field Dissipation of
Cyhalofop-butyl in USA Rice Culture Systems: Amended Report: Lab Project
Number: ENV98033. Unpublished study prepared by Dow AgroSciences LLC.
243 p. 

45000522	Olberding, E.; Yeh, L.; Foster, D. (1999) Validation Report for
the Determination of Residues of Cyhalofop-butyl and Metabolites in
Water by Capillary Gas Chromatography with Mass Spectrometry Detection
and Liquid Chromatography with Mass Spectrometry Detection: Lab Project
Number: RES98074. Unpublished study prepared by Dow AgroSciences LLC. 68
p. {OPPTS 850.7100} 

45000523	Olberding, E.; Yeh, L.; Foster, D. et al. (1999) Validation
Report for the Determination of Residues of Cyhalofop-butyl and
Metabolites in Sediment and Soil by Liquid Chromatography with Mass
Spectrometry Detection: Lab Project Number: RES98075. Unpublished study
prepared by Dow AgroSciences LLC. 76 p. {OPPTS 850.7100} 

45000524	Shimada, N. (1995) XRD-537 BE Soil Metabolism Study: Lab
Project Number: GHF-R-300: DPC/AE-1529-3G. Unpublished study prepared by
Daiichi Pure Chemicals Co., Ltd. 208 p. 

45000525	Shimada, N. (1995) XRD-537 BE Soil Leaching Study: Lab Project
Number: GHF-R-301: DPC/AE-1529-4G. Unpublished study prepared by Daiichi
Pure Chemicals Co., Ltd. 98 p. 

45014712	Merritt, D.; Concha, M.; Shepler, K. (1994) Degradation Study:
Photodegradation of (carbon-14)XRD-537 Butyl Ester (BE) in Sterilized
Buffer at pH 5 and Synthetic Humic Water Buffered at pH 5 by Natural
Sunlight: Lab Project Number: ENV93089: 426W. Unpublished study prepared
by Huntingdon Life Sciences Ltd. 155 p. 

45014713	Knowles, S. (1997) Estimation of Photochemical Oxidation of
Cyhalofop-Butyl Ester: Lab Project Number: GHE-P-5967: P97-002.
Unpublished study prepared by DowElanco Europe. 9 p. 

45014714	Jackson, R. (1997) The Sorption of DE-537 and its Degradation
Products in Soil: Lab Project Number: 3Y: GHE-P-6033. Unpublished study
prepared by DowElanco Europe. 53 p. 

45014715	Jackson, R. (1997) The Degradation of DE-537 and in European
Soils: Lab Project Number: 1Y: GHE-P-5680. Unpublished study prepared by
DowElanco Europe. 95 p. 

45000526	Ridge, M. (1999) The Degradation of (carbon 14)-DE-537 in
Natural Water/Sediment Systems: Lab Project Number: GHE-P-6032.
Unpublished study prepared by Corning Hazleton (Europe). 164 p. 

45204003	Thomas, A. (2000) Frozen Storage Stability of Cyhalofop-butyl
in Soil: Lab Project Number: 98077. Unpublished study prepared by Dow
AgroSciences LLC. 55 p. 

45204001	Thomas, A.; Robb, C. (2000) Frozen Storage Stability of
Cyhalofop-butyl and its Major Metabolites in Water: Lab Project Number:
990007. Unpublished study prepared by Dow AgroSciences LLC. 102 p.
{OPPTS 860.1380} 

45000521	Jenkins, W. (1997) DE-537, Technical: Activated Sludge,
Respiration Inhibition Test: Lab Project Number: GHE-T-731:
96/DES391/0806. Unpublished study prepared by Huntingdon Life Sciences
Ltd. 33 p. {OPPTS 850.6800} 

45573201	Knuteson, J. (2001) Surface Water Monitoring of Cyhalofop-Butyl
in a California Rice Growing Region in 2001: Lab Project Number: GH-C
5355: ML01-0939-DOW. Unpublished study prepared by Dow AgroSciences LLC.
138 p. 

47380601	Krieger, M. (2003) Drinking Water Monitoring in California for
Cyhalofop-butyl and Metabolites-2002. Project Number: GH/C/5637.
Unpublished study prepared by Dow AgroSciences, LLC. 93 p.

Appendix   SEQ Appendix \* ALPHABETIC  A .  Environmental Fate and
Transport Characterization

Cyhalofop-butyl is an aryloxphenoxypropionic (formerly oxyphenoxy acid
esters) class herbicide (Wood, 2007).  This class of herbicides
selectively inhibit de novo fatty acid biosynthesis, specifically
inhibiting an early step in fatty acids biosynthesis, the carboxylation
of Acetyl CoA to Malonyl-CoA, catalyzed by the enzyme acetyl CoA
carboxylase (USEPA, 2001).  The mode of action is to inhibit lipid
synthesis resulting in the disruption of cell walls (Tu et al., 2001).  
   REF _Ref211765286 \h  Table A 1  summarizes the identity information
associated with cyhalofop-butyl.

Table A   SEQ Table_A \* ARABIC  1 .  Chemical Identification for the
Active Ingredient Cyhalofop-butyl1

Parameter	Identity Information for Cyhalofop-butyl

Common Name:	Cyhalofop-butyl 

Pesticide Class:	aryloxphenoxypropionic herbicide

EPA PC Code:	082583

Product Chemistry Review of Cyhalofop-butyl Technical (Memo to J. Miller
from S. Mathur; DP Barcode D269915; April 26, 2001)

Enantiomer Considerations for Cyhalofop-butyl

Cyhalofop-butyl may exist as an R or S enantiomer.  The methods used in
studies have not specified whether they were specific to the R or S
enantiomer and no information is available on whether conversion of the
R enantiomer occurs in the environment.  Some information is known for a
similar compound fluazifop-butyl.  Studies on fluazifop-butyl suggest
that information on the R enantiomer should be adequate as that is the
enantiomer that is applied and its S form is either degraded faster or
converted to the R form in soil (USEPA, 2008).  However, we do not know
how cyhalofop-acid will behave in soils with a range of different
microbial populations or in water.   Due to these data gaps, exposure
may be viewed as the exposure to total residues of cyhalofop-butyl, with
assumptions that cyhalofop-butyl and cyhalofop-acid may be present in
the R or S form or as a mixture of the enantiomers.  More information on
the behavior of specific enantiomers in water or soils would reduce the
uncertainty on which enantiomer will predominate in the environment. 

Physicochemical Properties

Physical and chemical properties can be used to identify a priori the
potential behavior of a chemical in the environment.  Cyhalofop-butyl
has a vapor pressure of 0.053 mPa and estimated Henry’s law constants
ranging from 9.5 x 10-4 to 9.5 x 10-9 Pa-m3/mole, indicating it is not
likely to volatize substantially at environmental temperatures (  REF
_Ref211765346 \h  Table A 2 ; based on criteria in Corbin et al., 2006).
 It is slightly soluble with a water solubility of 0.44 mg/L (MRID
45000203) and has a moderate log KOW of  3.32, indicating that it has a
higher affinity for organics than for water (MRID 45000203; US EPA,
2001b) and has the potential to accumulate in organisms.    REF
_Ref211765346 \h  Table A 2  provides a summary of the physico-chemical
properties of cyhalofop-butyl and related compounds.

Cyhalofop-acid and diacid, two major degradates of cyhalofop-butyl, are
weak acids with an estimated pKa of 3.8.  At typical environmental pHs,
they will mainly be present in anionic form (assuming a pKa of 3.8,  61%
is ionized at pH 4, 94% ionized at pH 5, and greater than 99% is ionized
at pH 6 and higher).  Cyhalofop-acid is moderately to readily soluble in
water with water solubilities ranging from 9.8 to 152 mg/L (based on
criteria in FAO, 2000).  The log KOW ranged from -0.58 to 1.80, and it
is expected to have a higher affinity for organics and lower solubility
in its neutral form, e.g., at lower pH.  

Table A   SEQ Table_A \* ARABIC  2 .  Summary of physico-chemical
properties of cyhalofop-butyl and related compounds1

Property	Cyhalofop-butyl2	Cyhalofop-acid	Cyhalofop-amide
Cyhalofop-diacid

Empirical Formula	C20H20FNO4	C16H12FNO4	C16H14FNO5	C16H13FO6

Molecular weight (g/mole)	357.38	301.285 	319.295	320.285

Melting Point (oC)	45.5 – 49.5	182.04 (estimated)5	213.62 (estimated)5
200.06

(estimated)5

Boiling Point (oC)	270	437.52 (estimated)5	502.18 (estimated)5	473.17

(estimated)5

Density (g/mL; g/cc; or g/cm3)	1.172

	Dissociation Constant, pKa	Not measurable	3.802

< 3.8 (assumed)3

Vapor Pressure (Pa)	5.3 x 10-5

	3.07 x 10-6 (estimated)5	3.17 x 10-8 (estimated)5	2.47x10-7

(estimated)5

Henry’s Law Constant (atm-m3/mole)	9.4x10-9 

(calculated)	5.49 x 10-12 (estimated)5

2.34 x 10-16 (estimated)5

Water Solubility

(mg/L)

	0.44

0.6 at pH 2.5 and 25oC4

0.7 at pH 7 and 25oC4

0.7 at pH 8 and 25oC4

	177 at pH 2.802

251 at pH 7.062

9.80 at pH 9.802

0.1– 0.5 (estimated)3

58.22 (estimated)5

Log KOW	3.3158	1.80 at pH 42

-0.58 at pH 72

-0.68 at pH 102	1.91 (estimated)5	3.04 (estimated)5

Data that were not submitted in an MRID product chemistry study are not
primary sources and in general, these data are not used in modeling. 
However, physico-chemical properties are sometimes used when no primary
data are available or better information is available from other
sources.  

Data from MRID 45000203 as reviewed in Product Chemistry Review of
Cyhalofop-butyl Technical (Memo to J. Miller from S. Mathur; DP Barcode
269915; April 26, 2001)

Jackson, R. 1997. The sorption of DE-537 and its degradation products in
soil.  As reported in an e-mail message from M. Krieger, to B. Eckel on
March 13, 2001.

MRID 45014712, a metabolism study, reported these values.  The values
are not primary data.

Estimated by EPI-Suite version 3.20 and SMILES string shown in   REF
_Ref211765380 \h  \* MERGEFORMAT  Table A 3 .

Environmental Fate

This section summarizes environmental fate information for
cyhalofop-butyl and its degradates.  Cyhalofop-butyl degrades rapidly
via aerobic and anaerobic degradation.  The metabolites are identified
in   REF _Ref211765380 \h  Table A 3 ..  

Table A   SEQ Table_A \* ARABIC  3 .  Summary of major and minor
degradates of cyhalofop-butyl and the range of maximum percent of
applied equivalents in degradation studies1

Degradate Names

SMILES String

Structure	Maximum % applied equivalents

Major Degradates (Made up >10% of applied parent equivalents)

Cyhalofop-acid (CAS No. 122008-78-0); 

(R-(+)-2-[4-(2-fluoro-4-cyanophenoxy)phenoxy]propanoic acid); 

XRD-537 acid; 

(2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid 

SMILES String:  CC(OC1=CC=C(OC2=C(F)C(=CC=C2)C#N)C=C1)C(O)=O

	1.2 – 98.7

Cyhalofop–amide (CAS No. Unavailable); 

(2-[4-(4-aminocarboxyl-2-fluorophenoxy)phenoxy]propanoic acid); 

XRD-537 amide; 

2-[p-(4-carbamoyl-2-fluorophenoxy)phenoxy]propionic acid; 

2-[4-[4-(aminocarbonyl)-2-fluorophenoxy]phenoxyl]propanoic acid;

SMILES String:   CC(OC1=CC=C(OC2=C(F)C=C(C=C2)C(N)=O)C=C1)C(O)=O

	1.9 - 44.5

Cyhalofop-diacid (CAS No. Unavailable); 

(R-(+)-2-[4-(4-carboxy-2-fluorophenoxy)phenoxy]propanoic acid); 

XRD-537 diacid; 

4-[p-(1-carboxyethoxy) phenoxy]-3-fluorobenzoic acid;
4-[4-(1-carboxyethoxy)phenoxy]-3-fluorobenzoic acid

SMILES String:  CC(OC1=CC=C(OC2=C(F)C=C(C=C2)C(O)=O)C=C1)C(O)=O

	11.9 – 86.5

FHPBA (CAS No. Unavailable); 

3-fluoro-4-(4-hydroxyphenoxy)benzoic acid

	0.2 – 20.3

DP or FCPP; 

(4-(2-fluoro-4-cyanophenoxy)phenol); 

XRD-537 DP; 

3-fluoro-4-(4-hydroxyphenoxy)benzonitrile

	0.4 -12.0  

Minor Degradates (made up <10% of applied parent equivalents)

HPPA; 

(R-(+)-2-(4-hydroxyphenoxy)propanoic acid); 

(2R)-2-(4-hydroxyphenoxy)propanoic acid

	0.14 - 7.7

FHB; 

(3-fluoro-4-hydroxybenzonitrile); 

XRD-537 HBN

	0.19 – 0.37

This table is based on information from MARC Meeting:  Cyhalofop-butyl
residues in drinking water (Memo from W. Eckel to Y. Donovan; August 1,
2001), as well as information in   REF _Ref211941510 \h  \* MERGEFORMAT 
Table B 1  and gathered from Data Evaluation Records (DERs).

Simplified Molecular Input Line Entry System (SMILES) strings were
obtained by inputing the structure into the online SMILES Translator,
available at   HYPERLINK "http://cactus.nci.nih.gov/services/translate/"
 http://cactus.nci.nih.gov/services/translate/  (accessed September 23,
2008).

Abiotic Degradation 

Abiotic degradation rates for cyhalofop-butyl are slower than biotic
degradation rates.  Overall, hydrolysis half-lives for cyhalofop-butyl
increased with increasing pH and temperature and ranged from 0.5 days to
stable (  REF _Ref211765437 \h  Table A 4 ).  One study showed some
discrepancies with this trend, with significant degradation measured at
pH 1.2 at 37oC (half-life = 2 days; MRID 45000510); however, the pH is
not expected to occur commonly in the environment.  At low pH near 4 or
5, cyhalofop-butyl is expected to be stable, at pH near 7 rates will
half-lives ranged from >63 – 88 days, and at pH 9, cyhalofop-butyl
hydrolyzed within days (half-live = 2 days).  The hydrolysis rates
reported for 37oC corresponds to 98.6oF.  This temperature is not
expected to occur for prolonged periods in California; however, rates of
degradation may be greater in the Central Valley rather than in Northern
California.  Photodegradation rates in water ranged from 33 – 42 days
and cyhalofop-butyl was stable to photolysis in soil.  No data were
available on abiotic degradation rates of cyhalofop-butyl’s
degradates.  

Table A   SEQ Table_A \* ARABIC  4 .  Summary of Degradation and
Dissipation Studies for Cyhalofop-butyl and Related Compounds1

MRID Number (Year)

Status3 (Source)	Study Type

	Study Parameters

Half-life

 (days)2

Media	pH

%OC	Butyl	Acid	Amide	Diacid

45000510

(1995)

Supplemental (DER 2/23/2001)

	Hydrolysis 161-1	Sterile buffered water	1.2

4

7

9	2 at 37oC

>63 at 25oC

25 at 37oC

>63 at 25oC 

31 at 37oC

2  at 25oC

0.5 at 37oC

	45000511

(1999)

Acceptable (DER 2/23/2001)	Hydrolysis 161-1

	Sterile buffered water	5

7

9	Stable

88

2.1

	Pinna et al. (2008)	Hydrolysis	Sterile buffered water	4

7

9	347

85

2

	Non-sterile buffered water	4

7

9	4.8

1.0

0.8	301

--

12

45014712 (1994)

Supplemental (DER 2/26/2001)	Photolysis in water 161-2	Aqueous buffer
solution	5	41.5 (alpha)

36.7 (beta)

	Synthetic humic solution	5	32.7 (alpha)

	45000514

(1999)

Acceptable (DER 3/5/2001)	Photolysis on soil

161-3

	Silt loam soil (AR)	5.8

1.62%OM	Stable4

	45000524

(1995)

Supplemental (DER 3/12/2001)	Sterile control for aerobic aquatic soil
metabolism7	Sandy loam soil/distilled water (Japan)	6.3

6.15%OC

	Stable

	Sandy loam soil/distilled water (Japan)	6.3

0.96%OC	Stable

	45000515

(1999)

Acceptable (DER 3/8/2001)	Aerobic soil metabolism

162-1	Silt loam soil (AR)

Clay loam soil (CA)	5.8

1.62%OM

6.3

3.38%OM	LN=9

Nonlin.=0.10

2 comp.=0.09

LN=8

Nonlin.=0.12

2 comp.=0.12	Nonlin.=0.028

2 comp.=0.04

Nonlin.=0.036

2 comp.=0.04	2 comp

.=0.21

2 comp.

=0.12	2 comp.

=0.80

2 comp. =0.40

45000516

(1999)

Acceptable (DER 3/9/2001)	Aerobic soil metabolism 162-1	Silt loam soil
(AR)	5.8

1.62%OM	LN=2.32

Nonlin.=0.12

2 comp.=0.13

LN=2.61

Nonlin.=0.54

2 comp.=0.46	LN/=nr

Nonlin.=0.19

2 comp.=0.02

LN=nr 

Nonlin.=0.03

2 comp.=0.13	2 comp.

 = 0.35

2 comp.

=0.64	2 comp. =0.38

2 comp. =0.32

45014715

(1997)

Acceptable (DER 3/8/2001)

Recalculated Half-lives (DER Addendum 10/17/2008)	Aerobic soil

metabolism 162-1	Sandy loam5 (Italy)

Clay loam (Italy)

Loamy Sand (Germany)

Sandy clay loam (UK)	5.7/6.3

0.8%OC

5.0/6.1

1.0 %OC

6.1

2.3%OC

7.6/8.3

1.3%OC	LN=28

Nonlin.=0.1

Butyl+Bound=

Stable

LN=28

Nonlin.=0.1

Butyl+Bound=

Stable

LN=29

Nonlin.=0.2

Butyl+Bound= Stable

LN=44

Nonlin.=0.1

Butyl+Bound=

Stable	LN=52

Nonlin.=0.4

LN=47

Nonlin.=0.5

LN=36

Nonlin.=0.5

LN=33

Nonlin.=0.7	LN=23

Nonlin.=1.2

LN=15

Nonlin.=1.1

LN=3

Nonlin.=0.2

LN=24

Nonlin.=0.9	LN = 22

Nonlin.= 5.3

LN=13

Nonlin.=4.2

LN=7

Nonlin.=0.6

LN=20

Nonlin.=1.5

45000518

(1999)

Acceptable (DER 3/16/2001)	Aerobic aquatic metabolism 162-4	Flooded silt
loam sediment (AR)	5.4

1.27%OC	0.1

	7.6

	2.2

	14

45000526

(1996)

Acceptable (DER 3/15/2001)	Aerobic aquatic metabolism 162-4	Flooded silt
loam (Spain)

Flooded sand (France)	7.7-8.6

1.5%OC

6.6-6.9

1.5%OC

	1.7 - 4.4 hrs6

1.2-5.3 hrs6	4.5-7.5

5.6-8.5

	3.9-15.3

15.2-17.1

	7.9-17.6

37.3 – 43.3

Sterile Water/sand	6.6-6.9

1.5%OC

	Not stable

	Blasioli et al. (2008)	Aerobic aquatic metabolism	Paddy field sediment
+ water

Forest soil + water	5.5-6.0

14gOC/kg

6.8-7.1

73gOC/kg	1

1.3	13.7

0.6

Autoclaved paddy field sediment + water

Autoclaved forest soil + water	5.5-6.0

14gOC/kg

6.8-7.1

73gOC/kg	96.3

57.8	144

24.1

45000517

(1999)

Acceptable (DER 3/13/2001)	Anaerobic soil metabolism

162-2	Silt loam soil/pond water (AR)	5.8

1.62%OM	LN=0.5

Nonlin.=0.2

	LN=23

	LN=2.6

	Not determined 

45014715

(1997)

Acceptable (DER 3/8/2001)

Recalculated Half-lives (DER Addendum 10/17/2008)	Anaerobic aquatic
metabolism 162-2 or 162-3	Sandy loam soil/distilled water3 (Italy)

	5.7/6.3

0.8%OC

	Not reported	LN=23

Nonlin.=2.9

	LN=25

Nonlin.=2.5

	LN=21

Nonlin.=55

45000517

(1999)

Acceptable (DER 3/13/2001)	Anaerobic aquatic

metabolism

162-3	Silt loam sediment/

pond water (AR)	6.5

1.03%OM	LN=0.5

Nonlin.=0.2

	LN=54.8

	LN=2.8

	Not determined

45000520 (1999)

Acceptable (DER 4/17/2001)

	Aquatic field dissipation	Silt loam soil (AR) flooded

Residues measured in water	5.3-6.1

1.1%OC (soil)

7.5-7.6 (water)	Bare: 

LN =0.04 

Nonlin.=0.04

Cropped:

LN=0.03

Nonlin.=0.03	Bare: 

LN=1.23

Nonlin.=1.3

Cropped :

LN=0.79

Nonlin.=0.80	Bare: 

LN=0.41 

Nonlin.=1.9

Cropped :

LN=0.41

Nonlin.=1.4	Bare: 

LN=0.20

Nonlin.=1.9

Cropped :

LN=0.21

Nonlin.=1.5

Residues measured in soil	5.3-6.1

1.1%OC	

Not reported	Bare: 

LN=0.60

Nonlin.=0.3-0.4

Cropped :  

LN=0.60

Nonlin.=

0.3-0.4	Bare: 

LN=0.43

Nonlin.=  4.3-4.4

Cropped :  

LN=0.49

Nonlin.= 3.2-3.4	Bare: 

LN=0.55

Nonlin.=  16.8

Cropped :  

LN=3.0

Nonlin.=

15.5

	Aquatic field dissipation	Clay loam soil (CA) flooded

Residues measured in water	6.5-6.6

1.6-2.3%OC (soil)

7.0-7.2 (water)	Bare : 

LN=0.01 

Nonlin.=0.01

Cropped :

LN=0.01

Nonlin.=0.02	Bare: 

LN=1.82

Nonlin.=1.9

Cropped :

LN=1.82

Nonlin.=1.9	Bare: 

LN=0.20 

Nonlin.=2.1

Cropped :

LN=0.20

Nonlin.=2.1	Bare: 

LN=1.14

Nonlin.=3.6

Cropped :

LN=1.14

Nonlin.=3.6

Residues measured in soil	6.5-6.6

1.6-2.3%OC	

Not reported	Bare: 

LN = 0.60

Nonlin.=

0.3-0.4

Cropped :  

LN = 0.60

Nonlin.=

0.3-0.4	Bare: 

LN = 0.43

Nonlin.=  4.3-4.4

Cropped :  

LN=0.49

Nonlin.= 3.2-3.4	Bare: 

LN=0.55

Nonlin.=  16.8

Cropped :  

LN=3.0

Nonlin.= 15.5

Parveen et al. (2005)	Aquatic field dissipation	Rice paddy fields in
Japan	Not reported	<1 

0.99

	Abbreviations:  DER = data evaluation record; DT50 = dissipation time
of 50% of the chemical; alpha and beta refer to the radiolabeled ring. 

Half-live values are based a first order linear fit of the data
(plotting days after treatment x the natural log of percent applied),
unless otherwise specified.  When a study reported half-lives in
multiple ways this fit was designated with LN.   Nonlinear (Nonlin.)
indicates the half-life was determined using a first order equation and
a nonlinear first-order curve fit.  The two-compartment model (2 comp.)
took sorption into account in the calculations.

If the values were from the open literature it does not have a study
status because a standard classification method is not available.  The
results are reported because the information is still useful in
describing the environmental fate of substances in the environment. 

The reported half-life in the study was 0.5 days in both light and dark
controls (DER 3/5/2001).

These soils were from Italy, Germany, and the United Kingdom and were
not classified using the USDA classification system.

The validity of these half-lives is questionable because 59.1-65.9
percent of applied cyhalofop-butyl equivalents degraded immediately
after treatment (DER 3/15/2001).  Half-lives were based on 0 – 12 hour
and 0 – 24 hour time points.

The study results of the aerobic soil metabolism studies were invalid
for a number of reasons; however, the sterile controls of the study did
demonstrate that observed degradation was biotic rather than abiotic and
the study was classified as supplemental for this reason.

Biotic Degradation

Aerobic and anaerobic degradation of cyhalofop-butyl was rapid in
laboratory studies.  Half of the applied cyhalofop-butyl hydrolyzed to
cyhalofop-acid in 0.1 – 0.2 days in soil and 0.1-1.3 days in
aquatic/sediment/soil systems (  REF _Ref211765437 \h  Table A 4 ). 
Anaerobic half-lives were also less than a day.  The primary degradation
pathway is via microbially mediated hydrolysis.  Aerobic and anaerobic
degradation rates of cyhalofop-butyl’s degradates ranged from hours to
months; however, most degradation occurred within a week to a month.  

Field Studies

Dissipation of cyhalofop-butyl was examined in bare and cropped plots in
California and Arkansas (MRID 45000520).  In the Arkansas plot,
cyhalofop-butyl was applied to a dry field at 210 g a.i./hectare (ha)
followed by 310 g a.i./ha to the flooded field.  In the California
study, both applications were made to flooded plots.  The application
interval in both studies was 14-15 days.  Half of cyhalofop-butyl
applied equivalents dissipated in less than a day.  Half of
cyhalofop-acid and amide dissipated in 0.3 – 5 days.  Half of
cyhalofop-diacid dissipated in 0.2 to 16.8 days.  In water, residues
were not detected after 28 days.  In soils, residues were not detected
after 56 days.  The acid was only detected in the 0-7.6 cm soil depth. 
The amide had some interference in the method but was not detected below
7.6 cm.  Cyhalofop-diacid and FHPBA were detected at soil depths of
0-7.6 and 7.6-15.2 cm.  The analytical chemistry method in water was not
evaluated by an independent laboratory as required.  The environmental
chemistry method for the soil/sediment resulted in the butyl being
hydrolyzed to the acid.  Additionally, interference prevented analysis
of the amide in some circumstances.

Maximum concentrations in paddy water were:

cyhalofop-butyl 209 µg/L (15 days after the first application), 

cyhalofop-acid 278 µg/L (15 days after the first application),

cyhalofop-amide 29 µg/L (16 days after the first application),

cyhalofop-diacid 30 µg/L (17 days after the first application),

FHPBA 24 µg/L (18 days).

Maximum concentrations in soil were:

cyhalofop-butyl/acid 121 µg/kg (1 day after the first application),

cyhalofop-amide 34 µg/kg (7 days after the first application),

cyhalofop-diacid 35 µg/kg (16 days after the first application),

FHPBA 14 µg/kg (21 days after the first application).

Mobility

Cyhalofop-butyl

No acceptable studies on the sorption of cyhalofop-butyl have been
submitted.  A supplemental batch equilibrium was conducted with a 2-hour
equilibration time (MRID 45000519).  These measurements are not valid as
2-hours is not enough time to achieve equilibration, especially as
cyhalofop-butyl may have been degrading during this time.  However,
these values provide an initial estimate of soil-water distribution
coefficients (Kd) and organic carbon-water partition coefficients (KOC).
 Initial estimates of Kd values ranged from 17.8 – 75.0 L/kg and KOC
values ranged from 2892 – 7960 L/kg.  These values indicate that
cyhalofop-butyl is slightly mobile based on the NAFTA and FAO
classification systems (Corbin et al., 2006; FAO, 2000).  Due to its
short half-life it is not expected to commonly leach into groundwater.

Cyhalofop-Acid and other Degradates

Measured Kd and KOC values are summarized in   REF _Ref211765699 \h 
Table A 5 .  Based on the Kd values, results indicate the acid and amide
have the highest mobility and the diacid the lowest mobility.  However,
the diacid showed the lowest measured KOC.  The data indicated that the
mobility of the diacid may be highly dependent on the type of soil
present.  For example, it was highly mobile in a loamy sand soil and
less mobile in clay loam and sandy clay loam soils.  Higher mobility in
sandy soils and lower mobility in clay soils is commonly observed and
was probably not seen for the amide because sorption was only
characterized in one soil.  Additionally, mobility of the acid and amide
were not characterized in the sandy loam soil which may have shown
higher mobility for these compounds.  

The anion exchange capacity of most soils is small compared to their
cation exchange capacity.  Thus, anions (negatively-charged ions) tend
to be weakly sorbed to most soils (in effect, repelled by soil matrix
surfaces which are generally negatively charged).  Generally speaking,
other factors being the same, mobility is expected to decrease with pH
for weak acids as more of the compound will be present in its neutral
form at lower pH.  Additionally, the pH-dependent anion exchange
capacity increases as pH decreases.  Soil-water distribution
coefficients did not correlate to organic carbon.

Table A   SEQ Table_A \* ARABIC  5 .  Summary of the sorption data
available for the degradates of cyhalofop-butyl measured in MRID
45014714

Compound	Range of Measured Kd Values in L/kg	Range of Measured KOC
values in L/kg1	Ce range (µg/L)2	Mobility Classification3

Cyhalofop-acid	0.463 – 6.2 (10)4	57 - 254	7.4 - 5740	Medium to high

Cyhalofop-amide	0.3 – 0.47 (3)	38 - 59	1.17 – 3.03	High to very high

Cyhalofop-diacid	5.66 – 10.37 (5)	35 - 634	8.24 – 42.19	Low to very
high

KOC values, were calculated from the Kd as. KOC = Kd *100/% OC

Ce Range is the range of the analyte concentration in water at
equilibrium when the sorption coefficients were measured.

The mobility classification is based on the NAFTA terrestrial field
dissipation guidance available at   HYPERLINK
"http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.
htm#IIIA" 
http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.h
tm#IIIA  (Corbin et al., 2006).

The value in parentheses indicates the number of reported values.

Bioconcentration/Bioaccumulation

Bioconcentration was examined in rainbow trout (MRID 45000233). 
Bioconcentration factors (BCF) were calculated as the ratio of total
[14C]residues in the various fish tissues versus the average
concentration of cyhalofop-butyl in the exposure water from 7 to 28 days
(0.19 or 1.10 ng/mL).  Bioconcentration factors were lowest in muscle
(edible tissue) at 27 and highest in the viscera (nonedible tissue) at
507-672.  For the whole fish, BCFs ranged from 507 – 672.  Overall,
these results indicate that cyhalofop-butyl and its degradates will not
significantly bioconcentrate in organisms.

Degradates

Cyhalofop-acid was a major degradate in all environmental fate studies
submitted.  Cyhalofop-amide and cyhalofop-diacid were a major degradates
in the photolysis on soil, and aerobic and anaerobic metabolism studies.
 They appear primarily in the presence of microorganisms (Pinna et al.,
2008).  Degradates FHPBA and DP, made up maximums of 20 and 12% applied
parent equivalents, respectively, in environmental fate studies.  DP was
only a major degradate in the photodegradation on soil study and is
expected to be a minor degradate in the natural environment.  FHPBA was
a major degradate in the anaerobic aquatic metabolism study.  It would
only be expected to be a major degradate in benthic environments or when
oxygen levels were low.  

Appendix   SEQ Appendix \* ALPHABETIC  B .  Supplemental Information on
Degradates

    

Table B   SEQ Table_B \* ARABIC  1 .  Maximum Reported Amounts of
Cyhalofop-butyl and Its Degradation Products1,2,3,4

  SEQ CHAPTER \h \r 1 Chemical ID 	  SEQ CHAPTER \h \r 1 Maximum % of
Applied	Mean % of Applied at Study Termination or Last Time Point
Analyzed	Study Type	MRID

Cyhalofop-butyl	Not applicable	40.6 (2d, pH1.2, 37oC)

82.5 (40d, pH4, 37oC)

88.5 (63d, pH4, 25oC)

38.7 (40d, pH7, 37oC)

59.1 (63d, pH7, 25oC)

34.0 (0.6d pH9, 37oC)

α)

49.3 (30d, pH 5 buffer sol., light, β)

43.7 (30d, pH 5 humic water, α)	Photolysis in water

	47014712

	Not applicable	3.9 (30d, light, silt loam)

2.5 (30d, dark, silt loam)	Photolysis on soil	45000514

	Not applicable

	1.27 (120d, sandy loam, α)

1.58 (120d, sandy loam, β)

1.13 (120d, clay loam, α)

2.0 (120d, loamy sand, α)

4.0 (120d, sandy clay loam, α)	Aerobic soil metabolism

	45014715

	Not applicable	10 (12d, 10oC, silt loam)

9.5 (12d, 20oC, silt loam)	Aerobic soil metabolism	45000516

	Not applicable	3.1 (30d, silt loam)

2.1 (30d, clay loam)	Aerobic soil metabolism	45000515

	Not applicable

	nd (14d, silt loam, α)

nd (3d, silt loam, β)

nd (7d, sand, α)

nd (30d, sand, β)	Aerobic aquatic metabolism

	45000526

	Not applicable	nd (30d, water, silt loam, α)

nd (45d, sediment, silt loam, α)

nd (45d, total, silt loam, α)

	Aerobic aquatic metabolism	45000518

	Not applicable	nd (365d, water, silt loam)

nd (365d, soil, silt loam)

nd (365d, total, silt loam)	Anaerobic soil metabolism	45000517

	Not applicable	nd (120d, sandy loam, α)

nd (60d, sandy loam, β)	Anaerobic aquatic metabolism	45014715

	Not applicable	nd (365d, water, silt loam)

nd (365d, sediment, silt loam)

nd (365d, total, silt loam)	Anaerobic aquatic metabolism	45000517

Cyhalofop- acid	54.8 (2d, pH1.2, 37oC)

6.3 (40d, pH4, 37oC)

3.9 (63d, pH4, 25oC)

57.2 (40d, pH7, 37oC)

35.4 (56d, pH7, 25oC)

60.0 (0.6d pH9, 37oC)

37.8 (1.3d, pH9, 37oC)	53.1 (2d, pH1.2, 37oC)

5.8 (40d, pH4, 37oC)

3.4 (63d, pH4, 25oC)

55.1 (40d, pH7, 37oC)

29.7 (63d, pH7, 25oC)

α)

1.6 (30d, pH5 buffer sol., light, β)

1.2 (30d, pH 5 humic water, α)	1.3 (30d, pH 5 buffer sol., light, α)

0.9 (30d, pH 5 buffer sol., light, β)

0.9 (30d, pH 5 humic water, α)	Photolysis in water

	47014712

	53.2 (30d, light, silt loam)

47.0 (1d, dark, silt loam)	53.1 (30d, light, silt loam)

4.2 (30d, dark, silt loam)	Photolysis in soil	45000514

	21.75 (4h, sandy loam, α)

21.05 (4h, sandy loam, β)

18.71 (1h, clay loam, α)

13.22 (1h, loamy sand, α)

37.93 (4h, sandy clay loam, α)	1.41 (120d, sandy loam, α)

1.31 (120d, sandy loam, β)

1.36 (120d, clay loam, α)

0.54 (120d, loamy sand, α)

1.28 (120d, sandy clay loam, α)	

Aerobic soil metabolism

	45014715

	15.8 (0.5d, 10oC, silt loam)

12.6 (3d, 20oC, silt loam)	5.5 (12d, 10oC, silt loam)

6.8 (12d, 20oC, silt loam)	Aerobic soil metabolism	45000516

	14.8 (0.17d, silt loam)

15.7 (0.08d, clay loam)	1.1 (30d, silt loam)

1.2 (30d, clay loam)	Aerobic soil metabolism	45000515

	75.5 (1d, water, silt loam, α)

20.7 (0.16d, sediment, silt loam, α)

80.7 (1d, total, silt loam, α)	nd (45d, water, silt loam, α)

1.7 (45d, sediment, silt loam, α)

1.6 (45d, total, silt loam, α)	Aerobic aquatic  metabolism	45000518

	68.97 (12h, water, silt loam, α)

9.07 (12h, sediment, silt loam, α)

74.15 (12h, total, silt loam, α)

76.23 (12h, water, silt loam, β)

10.28 (7d, sediment, silt loam, β)

78.99 (12h, total, silt loam, β)

76.60 (12h, water, sand, α)

5.89 (3d, sediment, sand, α)

79.26 (12h, total, sand, α)

63.28 (6h, water, sand, β)

8.26 (14d, sediment, sand, β)

62.36 (12h, total, sand, β)	0.56 (98d, silt loam, α)

1.76 (98d, sediment, silt loam, α)

2.32 (98d, total, silt loam, α)

0.26 (30d, silt loam, β)

0.59 (62d, sediment, silt loam, β)

0.59 (98d, total, silt loam, β)

nd (62d, sand, α)

0.90 (98d, sediment, sand, α)

0.90 (98d, total, sand, α)

nd (62d, sand, β)

0.77 (98d, sediment, sand, β)

0.77 (98d, total, sand, β)	Aerobic aquatic metabolism

	45000526

	69.2 (1d, water, silt loam)

32.8 (0d, soil, silt loam)

93.3 (1d, total, silt loam)	1.8 (365d, water, silt loam)

1.8 (365d, soil, silt loam)

3.6 (365d, total, silt loam)	Anaerobic soil metabolism	45000517

	44.54 (1d, water, sandy loam, α)

30.93 (3d, soil, sandy loam, α)

68.80 (3d, system, sandy loam, α)

43.58 (1d, water, sandy loam, β)

24.24 (3d, soil, sandy loam, β)

66.92 (1d, total, sandy loam, β)	nd (60d, water, sandy loam, α)

1.87 (120d, soil, sandy loam, α)

1.87 (120d, system, sandy loam, α)

nd (30d, water, sandy loam, β)

2.45 (60d, soil, sandy loam, β)

2.45 (60d, total, sandy loam, β)	Anaerobic aquatic metabolism

	45014715

	68.6 (3d, water, silt loam)

30.3 (6d, sediment, silt loam)

95.8 (3d, total, silt loam)	4.75 (365d, water, silt loam)

2.35 (sediment, silt loam)

7.25 (total, silt loam)	Anaerobic aquatic metabolism	45000517

Cyhalofop-amide	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	Not reported	Not reported

	Photolysis in water	47014712

	13.5 (1d, light, silt loam)

13.5 (1d, dark, silt loam)	1.0 (30d, light, silt loam)

1.0 (30d, dark, silt loam)	Photolysis in soil	45000514

	35.49 (8h, sandy loam, α)

36.21 (8h, sandy loam, β)

30.42 (8h, clay loam, α)

16.16 (8h, loamy sand, α)

16.88 (8h, sandy clay loam, α)	nd (120d, sandy loam, α)

0.63 (120d, sandy loam, β)

nd (120d, clay loam, α)

nd (120d, loamy sand, α)

0.19 (120d, sandy clay loam, α)	Aerobic soil metabolism

	45014715

	44.5 (3d, 10oC, silt loam)

35.4 (6h, 20oC, silt loam)	14.3 (12d, 10oC, silt loam)

12.9 (12d, 20oC, silt loam)	Aerobic soil metabolism	45000516

	34.6 (0.17d, silt loam)

30.2 (0.25d, clay loam)	1.4 (30d, silt loam)

1.8 (30d, clay loam)	Aerobic soil metabolism	45000515

	21.7 (7d, water, silt loam, α)

3.4 (7d, sediment, silt loam, α)

19.6 (7d, total, silt loam, α)	1.55 (45d, water, silt loam α)

0.6 (45d, sediment, silt loam, α)

2.1 (45 d, total, silt loam, α)	Aerobic aquatic metabolism	45000518

	10.34 (24h, water, silt loam, α)

3.36 (3d, sediment, silt loam, α)

12.25 (24h, total, silt loam, α)

15.54 (7d, water, silt loam, β)

2.44 (7d, sediment, silt loam, β)

17.98 7d, total, silt loam, β)

21.13 (3d, water, sand, α)

7.05 (7d, sediment, sand, α)

25.95 (3d, total, sand, α)

18.59 (3d, water, sand, β)

12.13 (7d, sediment, sand, β)

28.15 (7d, total, sand, β)	0.52 (98d, silt loam, α)

0.84 (98d, sediment, silt loam, α)

1.36 (98d, total, silt loam, α)

nd (30d, silt loam, β)

0.21 (30d, sediment, silt loam, β)

0.21 (30d, total, silt loam, β)

nd (62d, sand, α)

0.45 (98d, sediment, sand, α)

0.45 (98d, total, sand, α)

0.18 (62d, sand, β)

1.36 (98d, sediment, sand, β)

1.36 (98d, total, sand, β)	Aerobic aquatic metabolism	45000526

	3.5 (28d, water, silt loam)

1.4 (6 and 14d, soil, silt loam)

7.3 (14d, total, silt loam)	nd (365d, water, silt loam)

(365d, soil, silt loam)

0.1 (365d, total, silt loam)	Anaerobic soil metabolism	45000517

	12.61 (1d, water, sandy loam, α)

10.96 (7d, soil, sandy loam, α)

19.81 (7d, total, sandy loam, α)

13.15 (7d, water, sandy loam, β)

12.48 (7d, soil, sandy loam, β)

25.63 (7d, total, sandy loam, β)	nd (60d, water, sandy loam, α)

0.98 (120d, soil, sandy loam, α)

0.98 (120d, total, sandy loam, α)

0.32(30d, water, sandy loam, β)

nd (60d, soil, sandy loam, β)

nd (60d, total, sandy loam, β)

	Anaerobic aquatic metabolism

	45014715

	3.9 (9d, water, silt loam)

1.9 (9d, sediment, silt loam)

5.5 (9d, total, silt loam)	0.2 (water, silt loam)

nd (sediment, silt loam)

0.2 (total, silt loam)	Anaerobic aquatic metabolism	45000517

Cyhalofop-diacid	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	Not reported	Not reported	Photolysis in water	47014712

	36.2 (14d, light, silt loam)

69.5 (30d, dark, siltl loam)	0.7 (30d, light, silt loam)

α)

34.08 (1d, sandy loam, β)

40.07 (1d, clay loam, α)

22.37 (8h, loamy sand, α)

28.41 (1d, sandy clay loam, α)	nd (120d, sandy loam, α)

0.85 (120d, sandy loam, β)

nd (120d, clay loam, α)

nd (120d, loamy sand, α)

0.20 (120d, sandy clay loam, α)	Aerobic soil metabolism

	45014715

	55.2 (12d, 10oC, silt loam)

48.7 (6d, 20oC, silt loam)	55.2 (12d, 10oC, silt loam)

39.9 (12d, 20oC, silt loam)	Aerobic soil metabolism	45000516

	42.7 (1d, silt loam)

42.8 (1d, clay loam)	3.6 (30d, silt loam)

α)

30.04 (30d, sediment, silt loam, α)

31.8 (15d, total, silt loam, α)	nd (45d, water, silt loam, α)

0.4 (45d, sediment, silt loam, α)

0.4 (45d, total, silt loam, α)	Aerobic aquatic metabolism	45000518

	23.12 (7d, water, silt loam, α)

7.51 (14d, sediment, silt loam, α)

30.10 (7d, total, silt loam, α)

35.86 (14d, water, silt loam, β)

12.86 (30d, sediment, silt loam, β)

47.77 (14d, total, silt loam, β)

55.58 (14d, water, sand, α)

11.13 (30d, sediment, sand, α)

66.20 (14d, total, sand, α)

55.58 (14d, water, sand, β)

11.13 (30d, sediment, sand, β)

66.20 (14d, total, sand, β)	0.82 (98d, silt loam, α)

2.32 (98d, sediment, silt loam, α)

3.14 (98d, total, silt loam, α)

29.81 (30d, silt loam, β)

0.90 (62d, sediment, silt loam, β)

0.92 (62d, total, silt loam, β)

nd (62d, sand, α)

13.29 (98d, sediment, sand, α)

13.29 (98d, total, sand, α)

nd (62d, sand, β)

13.29 (98d, sediment, sand, β)

13.29 (98d, total, sand, β)	Aerobic aquatic metabolism	45000526

	71.3 (252d, water, silt loam)

14.2 (252d, soil, silt loam)

86.5 (365d, total, silt loam)	69.0 (365d, water, silt loam)

14.0 (365d, soil, silt loam)

84.8 (365d, soil, silt loam)	Anaerobic soil metabolism	45000517

	44.64 (1d4, water, sandy loam, α)

36.91 (14d, soil, sandy loam, α)

81.55 (14d, total, sandy loam, α)

33.67 (30d, water, sandy loam, β)

22.17 (62d, soil, sandy loam, β)

42.66 (62d, total, sandy loam, β)	26.84 (60d, water, sandy loam, α)

3.21 (120d, soil, sandy loam, α)

3.21 (120d, total, sandy loam, α)

20.49 (62d, water, sandy loam, β)

15.50 (98d, soil, sandy loam, β)

15.50 (98d, total, sandy loam, β)	Anaerobic aquatic metabolism

	45014715

	46.2 (365d, water, silt loam)

11.9 (252d, sediment, silt loam)

57.0 (365d, total, silt loam)	45.15 (365d, water, silt loam)

10.35 (365d, sediment, silt loam)

55.5 (365d, total, silt loam)	Anaerobic aquatic metabolism	45000517

FCPP or DP	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	2.0 (30d, pH5 buffer sol., light, α)

1.9 (30d, pH5 buffer sol., light, β)

2.4 (30d, pH 5 humic, water, α)	2.0 (30d, pH5 buffer sol., light, α)

1.6 (30d, pH5 buffer sol., light, β)

1.6 (30d, pH 5 humic water, α)	Photolysis in water	47014712

	12.0 (30d, light, silt loam)

1.4 (14d, dark, silt loam)	10.5 (30d, light, silt loam)

0.4 (30d, dark, silt loam)	Photolysis on soil	45000514

	Not reported	Not reported	Aerobic soil metabolism	45014715

	Not reported	Not reported	Aerobic soil metabolism	45000516

	Not reported	Not reported	Aerobic soil metabolism	45000515

	0.9 (1d, water, silt loam, α)

0.4 (1d, 15d, 45d, sediment, silt loam, α)

0.9 (1d, total, silt loam, α)	nd (45d, silt loam, α)

0.2 (45d, silt loam, α)

0.45 (45d, silt loam, α)	Aerobic aquatic metabolism	45000518

	1.19 (7d, water, silt loam, α)

0.58 (3d, sediment, silt loam, α)

1.19 (12h, total, silt loam, α)

1.88 (6h, water, silt loam, β)

0.75 (3d, sediment, silt loam, β)

1.88 (6h, total, silt loam, β)

1.43 (24h, water, sand, α)

nd (98d, sediment, sand, α)

1.43 (24h, total, sand, α)

1.23 (24h, water, sand, β)

nd (98d, sediment, sand, β)

1.23 (24h, total, sand, β)	nd (98d, silt loam, α)

nd (98d, sediment, silt loam, α)

nd (98d, total, silt loam, α)

0.20 (30d, silt loam, β)

0.43 (62d, sediment, silt loam, β)

0.42 (62d, total, silt loam, β)

nd (62d, sand, α)

nd (98d, sediment, sand, α)

nd (98d, total, sand, α)

0.33 (62d, sand, α)

nd (98d, sediment, sand, β)

0.33 (62d, total, sand, β)	Aerobic aquatic metabolism	45000526

	Not reported	Not reported	Anaerobic soil metabolism	45000517

	Not reported	Not reported	Anaerobic aquatic metabolism	45014715

	Not reported	Not reported	Anaerobic aquatic metabolism	45000517

HPPA	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	Not reported	Not reported	Photolysis in water	47014712

	1.1 (21d, light, silt loam)

1.4 (14d, dark, silt loam)	0.4 (30d, light, silt loam)

0.4 (30d, dark, silt loam)	Photolysis on soil	45000514

	Not reported	Not reported	Aerobic soil metabolism	45014715

	Not reported	Not reported	Aerobic soil metabolism	45000516

	Not reported	Not reported	Aerobic soil metabolism	45000515

	2.0 (15d, water, silt loam, α)

0.6 (45d, sediment, silt loam, α)

2.4 (45d, total, silt loam, α)	2.1 (45d, silt loam, α)

0.3 (45d, silt loam, alph)

2.4 (45d, total, silt loam, α)	Aerobic aquatic metabolism	45000518

	0.14 (98d, water, silt loam, α)

nd (3d, sediment, silt loam, α)

0.14 (98d, total, silt loam, α)

0.14 (98d, total, silt loam, β)

0.49 (7d, water, sand, α)

1.83 (62d, sediment, sand, α)

1.83 (62d, total, sand, α)

0.24 (98d, total, sand, β)	0.14 (98d, silt loam, α)

nd (98d, sediment, silt loam, α)

0.14 (98d, total, silt loam, α)

nd (98d, total, silt loam, β)

nd (62d, sand α)

0.24(98d, sediment, sand, α)

0.24 (98d, total, sand, α)

0.24 (98d, total, sand, β)	Aerobic aquatic metabolism	45000526

	5.0 (365d, water, silt loam)

0.9 (252d, soil, silt loam)

5.8 (365d, total, silt loam)	5.0 (365d, water, silt loam)

0.8 (365d, soil, silt loam)

5.8 (365d, total, silt loam)	Anaerobic soil metabolism	45000517

	Not reported	Not reported	Anaerobic aquatic metabolism	45014715

	6.1 (365d, water, silt loam)

1.6 (365d, sediment, silt loam)

7.7 (365d, total, silt loam)	6.1 (365d, water silt loam)

1.6 (365d, sediment, silt loam)

7.7 (365d, total, silt loam)	Anaerobic aquatic metabolism	45000517

FHB	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	Not reported	Not reported	Photolysis in water	47014712

	Not reported	Not reported	Photolysis on soil	45000514

	Not reported	Not reported	Aerobic soil metabolism	45014715

α)

0.21 (3d, sediment, silt loam, β)

0.37 (98d, sediment, sand, α)

0.19 (6h, sediment, sand, β)	nd (silt loam, α)

nd (62d, sediment, silt loam, β)

0.37 (98d, sediment, sand, α)

nd (98d, sediment, sand, β)	Aerobic aquatic metabolism	45000526

	Not reported	Not reported	Anaerobic soil metabolism	45000517

	Not reported	Not reported	Anaerobic aquatic metabolism	45014715

	Not reported	Not reported	Anaerobic aquatic metabolism	45000517

FHPBA	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	Not reported	Not reported	Photolysis in water	47014712

	3.0 (30d, light, silt loam)

1.2 (30d, dark, silt loam)	2.6 (30d, light, silt loam)

1.0 (30d, dark, silt loam)	Photolysis on soil	45000514

	Not reported	Not reported	Aerobic soil metabolism	45014715

	Not reported	Not reported	Aerobic soil metabolism	45000516

	Not reported	Not reported	Aerobic soil metabolism	45000515

	7.4 (15d, water, silt loam, α)

1.4 (30d, sediment, silt loam, α)

5.9 (15d, total, silt loam, α)	nd (45d, water, silt loam, α)

0.7 (45d, sediment, silt loam, α)

0.7 (45d, total, silt loam, α)	Aerobic aquatic metabolism	45000518

	Not reported	Not reported	Aerobic aquatic metabolism	45000526

	1.0 (252d, water, silt loam)

0.2 (126d, 168d, soil, silt loam)

1.0 (252d, total, silt loam)	0.6 (365d, water, silt loam)

nd (365d, soil, silt loam)

0.6 (365d, total, silt loam)	Aerobic soil metabolism	45000517

	Not reported	Not reported	Anaerobic aquatic metabolism	45014715

	14.1 (365d, water, silt loam)

6.7 (252d, sediment, silt loam)

20.3 (252d, total, silt loam)	8.3 (365d, water silt loam)

5.2 (365d, sediment, silt loam)

18.5 (365d, total, silt loam)	Anaerobic aquatic metabolism	45000517

Unidentified Volatiles	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	0.4 (30d, pH5 buffer sol., light, α)

1.1 (30d, pH5 buffer sol., light, β)

0.2 (30d, pH 5 humic water, α)	0.4 (30d, pH5 buffer sol., light, α)

1.1 (30d, pH5 buffer sol., light, β)

0.2 (30d, pH 5 humic water, α)	Photolysis in water	47014712

	7.9 (30d, light and dark, silt loam)

	3.8 (30d, light and dark, silt loam)	Photolysis on soil	45000514

	37.98 (120d, sandy loam, α)

46.36 (120d, sandy loam, β)

40.90 (120d, clay loam, α)

37.87 (90d, loamy sand, α)

36.12 (120d, sandy clay loam, α)	37.98 (120d, sandy loam, α)

46.36 (120d, sandy loam, β)

40.90 (120d, clay loam, α)

37.97 (120d, loamy sand, α)

36.12 (120d, sandy clay loam, α)	Aerobic soil metabolism

	45014715

	Not reported	Not reported	Aerobic soil metabolism	45000516

	Not reported	Not reported	Aerobic soil metabolism	45000515

	3.7 (365d, silt loam)	2.45 (365d, silt loam)	Anaerobic soil metabolism
45000517

	Not reported	Not reported	Aerobic aquatic metabolism	45000518

	1.34 (62d, silt loam, α)

1.38 (98d, silt loam, β)

0.78 (98d, sand, α)

1.80 (30d, sand, β)	1.11 (98d, silt loam, α)

1.38 (98d, silt loam, β)

0.78 (98d, sand, α)

0.35 (98d, sand, β)	Aerobic aquatic metabolism	45000526

	45.47 (120d, sandy loam, α)

61.40 (60d, sandy loam, β)	45.47 (120d, sandy loam, α)

53.28 (120d, sandy loam, β)	Anaerobic aquatic metabolism	45014715

	6.6 (252d, silt loam)	4.35 (365d, silt loam)	Anaerobic aquatic
metabolism	45000517

Unknown/

Unextracted 

Soil or Sediment Residue 	Not reported	Not reported	Hydrolysis	45000510

	Not reported	Not reported	Hydrolysis	45000511

	13.9 (30d, pH5 buffer sol., light, α)

16.1 (30d, pH5 buffer sol., light, β)

16.9 (30d, pH 5 humic water, α)	13.9 (30d, pH5 buffer sol., light, α)

15.7 (30d, pH5 buffer sol., light, β)

15.8 (30d, pH 5 humic water, α)	Photolysis in water

	47014712

	24.0 (30d, light, silt loam)

8.1 (30d, dark, silt loam)	21.8 (30d, light, silt loam)

7.2 (30d, dark, silt loam)	Photolysis on soil

	45000514

	42.68 (30d, sandy loam, α)

41.48 (30d, sandy loam, β)

41.39 (30d, clay loam, α)

51.52 (7d, loamy sand, α)

53.65 (14d, sandy clay loam, α)	34.79 (120d, sandy loam, α)

33.65 (120d, sandy loam, β)

34.64 (120d, clay loam, α)

44.11 (120d, loamy sand, α)

44.24 (120d, sandy clay loam, α)	Aerobic soil metabolism	45014715

	19.9 (12d, 10oC, silt loam)

30.0 (12d, 20oC, silt loam)	19.9 (12d, 10oC, silt loam)

30.0 (12d, 20oC, silt loam)	Aerobic soil metabolism	45000516

	44.6 (30d, silt loam)

60.2 (7d, clay loam)	38.0 (30d, silt loam)

α)	35.8 (silt loam, α)	Aerobic aquatic metabolism 	45000518

	27.62 (30d, silt loam, α)

26.89 (98d, silt loam, β)

17.59 (62d, sand, α)

18.38 (98d, sand, β)	25.71 (98d, silt loam, α)

26.89 (98d, silt loam, β)

17.13 (98d, sand, α)

18.38 (98d, sand, β)	Aerobic aquatic metabolism	45000526

	0.8 (84d, silt loam)	0.6 (365d, silt loam)	Anaerobic soil metabolism
45000517

	19.78 (120d, sandy loam, α)

19.08 (120d, sandy loam, β)	19.78 (120d, sandy loam, α)

19.08 (120d, sandy loam, β)	Anaerobic aquatic metabolism	45014715

	1.6 (252d, silt loam)	1.3 (365d, silt loam)	Anaerobic aquatic
metabolism	45000517

Abbreviations:  h= hour; d=days; nd= not detected; nr = not reported; α
and β indicate the radiolabeled ring

Major degradates and maximum amounts for degradates >10% are in bold. 
Unacceptable data were not reported.  Refer to   REF _Ref211765380 \h 
\* MERGEFORMAT  Table A 3  for chemical names and structures.

No information was provided on whether cyhalofop-butyl or cyhalofop-acid
were present in the R or S form.  The R form was the starting material
in all studies.

The aquatic dissipation studies did not report results in percent of
applied parent equivalents and the results are not included in this
table.

Appendix   SEQ Appendix \* ALPHABETIC  C .   Environmental Fate
Modeling Information

Table C   SEQ Table_C \* ARABIC  1 .  Summary of sorption data for
cyhalofop-acid

Study	Soil	%OM	Kd (L/kg)	KOC (L/kg)

45014714 Supplemental (DER 4/9/2001)	Tenuta Crimea/Sandy Loam (Italy)
1.36	1.41	176

	Castello Mora/Clay Loam (Italy)	1.7	1.95	195

45000519 (1999)    Supplemental (DER 3/19/2001)	Silt loam (MS)	1.55	8.2
66.7

	Loamy sand (GA)	1.06	7.4	75.1

	Silt loam (AR)	1.62	5.8	152

	Clay loam soil (CA)	3.38	6.3	57.2

	clay loam soil (ND)	8.19	6	130

Mean	5.29	121.71

Standard Deviation	2.61	55.78

Coefficient of Variation	49%	46%

Lowest	1.41	57.2

Highest	8.2	195

Figure C   SEQ Figure_C \* ARABIC  1 .  Relationship between percent
organic matter and the measured soil-water distribution coefficient (Kd)
values for cyhalofop-acid

Table C   SEQ Table_C \* ARABIC  2 .  Summary of all sorption data used
to estimate input parameters for the Tier I Rice Model

Study	Soil	%OM	Kd (L/kg)	KOC (L/kg)

Cyhalfop-acid

45014714 Supplemental (DER 4/9/2001)	Tenuta Crimea/Sandy Loam (Italy)
1.36	0.8	100

1.36	1.45	181

1.36	1.35	168

1.36	2.03	254

	Castello Mora/Clay Loam (Italy)	1.7	1.95	195

45000519 (1999)    Supplemental (DER 3/19/2001)	Silt loam (MS)	1.55
0.601	66.7

	Loamy sand (GA)	1.06	0.463	75.1

	Silt loam (AR)	1.62	1.43	152

	Clay loam soil (CA)	3.38	1.13	57.2

	clay loam soil (ND)	8.19	6.2	130

Cyhalofop-diacid

45014714 Supplemental (DER 4/9/2001)	Castello Mora/Clay Loam (Italy)	1.7
6.34	634

	5.93	593

	Speyer 2.2/Loamy Sand (Germany)	3.91	8.4	123

	10.37	35

	Marcham/Sandy clay loam (UK)	2.21	5.66	435

 

Average	3.61	213.27

Standard Deviation	3.22	189.71

Coefficient of Variation	89%	89%

Low	0.463	35

High	10.37	634

Table C   SEQ Table_C \* ARABIC  3 .  Summary of aerobic aquatic
degradation half-lives for total residues of cyhalofop-butyl,
cyahofop-acid, and cyhalofop-diacid used in the Tier I Rice Model 

MRID	Value or Equation. 

	Linear/natural log DT50 (days), y = mx+b	Nonlinear/normal  y= a(-bx)
Observed DT50	Observed DT90

	m	b	DT50 (Days)	r2	a	b	DT50 (days)	r2

45000526	-0.02523	4.381252	27.46	0.7034	82.8384	0.0267	26.0	0.9569	17-62
days	not reached

45000526	-0.0178	4.2455	38.97	0.6689	71.5343	0.0165	42.0	0.8631	30-98
days	not reached

45000518	-0.0717	4.6777	9.66	0.8245	91.6842	0.0376	18.4	0.9376	15-45
days	30-45 days

Average	-0.038	4.43	25.37	0.73	82.02	0.027	28.80	0.92

number of values = n	3.000	3.00	3.00	3.00	3.00	3.000	3.00	3.00

t90, alpha = 0.1 n-1 = 2	1.886	1.89	1.89	1.89	1.89	1.886	1.89	1.89

standard deviation	0.029	0.22	14.77	0.08	10.10	0.011	12.04	0.05

square root of n	1.732	1.73	1.73	1.73	1.73	1.732	1.73	1.73

upper confidence bound on the mean	-0.006	4.68	41.45	0.82	93.02	0.038
41.91	0.97

Table C   SEQ Table_C \* ARABIC  4 .  Summary of aerobic aquatic
degradation half-lives for total residues of cyhalofop-butyl,
cyahofop-acid, cyhalofop-diacid, and unextracted residues 

MRID	Value or Equation

	Linear/natural log DT50 (days), y = mx+b	Nonlinear/normal  y= a(-bx)
Observed DT50	Observed DT90

	m	b	DT50 (Days)	r2	a	b	DT50 (days)	r2

45000526	-0.01023	4.418685	67.77	0.803955	83.9517	0.0118	58.7	0.8872
30-98 days	not reached

45000526	-0.0139	4.2889	50.01	0.6030	76.1179	0.0149	46.5	0.8416	30-98
days	not reached

45000518	-0.0170	4.5109	40.72	0.8722	90.5454	0.016	43.3	0.936	30-45 days
not reached

Average	-0.0137	4.41	52.83	0.760	83.54	0.0142	49.53	0.888

number of values = n	3.0000	3.00	3.00	3.000	3.00	3.0000	3.00	3.000

t90, alpha = 0.1 n-1 = 2	1.8860	1.89	1.89	1.886	1.89	1.8860	1.89	1.886

standard deviation	0.0034	0.11	13.74	0.140	7.22	0.0022	8.14	0.047

square root of n	1.7321	1.73	1.73	1.732	1.73	1.7321	1.73	1.732

upper confidence bound on the mean	-0.0100	4.53	67.80	0.912	91.40	0.0166
58.39	0.940

Table C   SEQ Table_C \* ARABIC  5 .  Summary of aerobic soil
degradation half-lives for total residues of cyhalofop-butyl,
cyahofop-acid, cyhalofop-diacid, and unextracted residues 

MRID	Soil	Label	Value or Equation

	Linear/natural log Half-life (days)                                    
 y = mx+b

	m	b	DT50 (Days)	r2

45014715	Sandy Loam	Both	-0.005	4.13	130	0.5163

45014715	Clay Loam	alpha	-0.006	4.20	118	0.6597

45014715	Loamy Sand	alpha	-0.005	4.25	145	0.5781

45014715	Sandy Clay Loam	alpha	-0.004	4.31	165	0.5791

45000515	Silt Loam	both	-0.021	4.25	32.55	0.4063

45000515	Silt Loam	both	-0.015	4.36	44.84	0.5378

Average	-0.0095	4.25	106.0

	number of values = n	6	6	6

	t90, alpha = 0.1 n-1 = 7	1.476	1.476	1.476

	standard deviation	0.0071	0.079	55

	square root of n	2.45	2.45	2.45

	upper confidence bound on the mean	-0.0052	4.30	138.92

	

Table C   SEQ Table_C \* ARABIC  6 .  Summary of aerobic soil
degradation half-lives for total residues of cyhalofop-butyl,
cyahofop-acid, and cyhalofop-diacid. 

MRID	Soil	Label	Value or Equation

	Linear/natural log Half-life (days)                                    
 y = mx+b

	m	b	DT50 (Days)	r2

45014715	Sandy Loam	Both	-0.027	3.526592	25	0.6207

45014715	Clay Loam	alpha	-0.0293	3.7342	24	0.770

45014715	Loamy Sand	alpha	-0.026	3.291	27	0.5270

45014715	Sandy Clay Loam	alpha	-0.0212	3.5921	33	0.5139

45000515	Silt Loam (AR)	both	-0.0746	3.825527	9.29	0.617521

45000515	Clay Loam (CA)	both	-0.08757	3.751842	7.91	0.623729

Average	-0.0443	3.62	21

	number of values = n	6	6	6

	t90, alpha = 0.1 n-1 = 7	1.4760	1.4760	1.4760

	standard deviation	0.0289	0.20	10

	square root of n	2.4495	2.45	2

	upper confidence bound on the mean	-0.0269	3.74	27

	

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kd

.394	1.39	2.78	2.84E-17	4.57E-16	4.86E-16

139	129	1.341	1.33	2.68	2.07E-17	3.33E-16	3.54E-16

140	130	1.291	1.28	2.57	1.51E-17	2.43E-16	2.58E-16

141	131	1.242	1.24	2.48	1.10E-17	1.77E-16	1.88E-16

142	132	1.195	1.19	2.38	7.99E-18	1.29E-16	1.37E-16

143	133	1.150	1.14	2.29	5.82E-18	9.37E-17	9.96E-17

144	134	1.107	1.10	2.21	4.24E-18	6.83E-17	7.25E-17

145	135	1.065	1.06	2.12	3.09E-18	4.97E-17	5.28E-17

146	136	1.025	1.02	2.04	2.25E-18	3.62E-17	3.85E-17

147	137	0.987	0.98	1.97	1.64E-18	2.64E-17	2.80E-17

148	138	0.949	0.94	1.89	1.19E-18	1.92E-17	2.04E-17

149	139	0.914	0.91	1.82	8.69E-19	1.40E-17	1.49E-17

150	140	0.879	0.87	1.75	6.33E-19	1.02E-17	1.08E-17

151	141	0.846	0.84	1.69	4.61E-19	7.43E-18	7.89E-18

152	142	0.814	0.81	1.62	3.36E-19	5.41E-18	5.75E-18

153	143	0.783	0.78	1.56	2.45E-19	3.94E-18	4.19E-18

154	144	0.754	0.75	1.50	1.78E-19	2.87E-18	3.05E-18

155	145	0.726	0.72	1.45	1.30E-19	2.09E-18	2.22E-18

156	146	0.698	0.69	1.39	9.45E-20	1.52E-18	1.62E-18

157	147	0.672	0.67	1.34	6.89E-20	1.11E-18	1.18E-18

158	148	0.647	0.64	1.29	5.02E-20	8.08E-19	8.58E-19

159	149	0.622	0.62	1.24	3.65E-20	5.89E-19	6.25E-19

160	150	0.599	0.60	1.19	2.66E-20	4.29E-19	4.55E-19

161	151	0.576	0.57	1.15	1.94E-20	3.12E-19	3.32E-19

162	152	0.555	0.55	1.11	1.41E-20	2.28E-19	2.42E-19

163	153	0.534	0.53	1.06	1.03E-20	1.66E-19	1.76E-19

164	154	0.514	0.51	1.02	7.49E-21	1.21E-19	1.28E-19

165	155	0.494	0.49	0.99	5.46E-21	8.79E-20	9.34E-20

166	156	0.476	0.47	0.95	3.98E-21	6.40E-20	6.80E-20

167	157	0.458	0.46	0.91	2.90E-21	4.67E-20	4.95E-20

168	158	0.440	0.44	0.88	2.11E-21	3.40E-20	3.61E-20

169	159	0.424	0.42	0.85	1.54E-21	2.48E-20	2.63E-20

170	160	0.408	0.41	0.81	1.12E-21	1.80E-20	1.91E-20

171	161	0.393	0.39	0.78	8.15E-22	1.31E-20	1.39E-20

172	162	0.378	0.38	0.75	5.94E-22	9.57E-21	1.02E-20

173	163	0.363	0.36	0.73	4.32E-22	6.97E-21	7.40E-21

174	164	0.350	0.35	0.70	3.15E-22	5.08E-21	5.39E-21

175	165	0.337	0.33	0.67	2.29E-22	3.70E-21	3.93E-21

176	166	0.324	0.32	0.65	1.67E-22	2.69E-21	2.86E-21

177	167	0.312	0.31	0.62	1.22E-22	1.96E-21	2.08E-21

178	168	0.300	0.30	0.60	8.87E-23	1.43E-21	1.52E-21

179	169	0.289	0.29	0.58	6.46E-23	1.04E-21	1.11E-21

180	170	0.278	0.28	0.55	4.71E-23	7.58E-22	8.05E-22

181	171	0.267	0.27	0.53	3.43E-23	5.52E-22	5.86E-22

182	172	0.257	0.26	0.51	2.50E-23	4.02E-22	4.27E-22

183	173	0.248	0.25	0.49	1.82E-23	2.93E-22	3.11E-22

184	174	0.238	0.24	0.48	1.32E-23	2.13E-22	2.27E-22

185	175	0.229	0.23	0.46	9.65E-24	1.55E-22	1.65E-22

186	176	0.221	0.22	0.44	7.03E-24	1.13E-22	1.20E-22

187	177	0.212	0.21	0.42	5.12E-24	8.25E-23	8.76E-23

188	178	0.204	0.20	0.41	3.73E-24	6.01E-23	6.38E-23

189	179	0.197	0.20	0.39	2.72E-24	4.38E-23	4.65E-23

190	180	0.189	0.19	0.38	1.98E-24	3.19E-23	3.39E-23

191	181	0.182	0.18	0.36	1.44E-24	2.32E-23	2.47E-23

192	182	0.175	0.17	0.35	1.05E-24	1.69E-23	1.80E-23

193	183	0.169	0.17	0.34	7.65E-25	1.23E-23	1.31E-23

194	184	0.162	0.16	0.32	5.57E-25	8.97E-24	9.53E-24

195	185	0.156	0.16	0.31	4.06E-25	6.54E-24	6.94E-24

196	186	0.150	0.15	0.30	2.95E-25	4.76E-24	5.06E-24

197	187	0.145	0.14	0.29	2.15E-25	3.47E-24	3.68E-24

198	188	0.139	0.14	0.28	1.57E-25	2.53E-24	2.68E-24

199	189	0.134	0.13	0.27	1.14E-25	1.84E-24	1.95E-24

200	190	0.129	0.13	0.26	8.32E-26	1.34E-24	1.42E-24

201	191	0.124	0.12	0.25	6.06E-26	9.76E-25	1.04E-24

202	192	0.119	0.12	0.24	4.41E-26	7.11E-25	7.55E-25

203	193	0.115	0.11	0.23	3.21E-26	5.18E-25	5.50E-25

204	194	0.111	0.11	0.22	2.34E-26	3.77E-25	4.01E-25

205	195	0.106	0.11	0.21	1.71E-26	2.75E-25	2.92E-25

206	196	0.102	0.10	0.20	1.24E-26	2.00E-25	2.13E-25

207	197	0.099	0.10	0.20	9.05E-27	1.46E-25	1.55E-25

208	198	0.095	0.09	0.19	6.59E-27	1.06E-25	1.13E-25

209	199	0.091	0.09	0.18	4.80E-27	7.74E-26	8.22E-26

210	200	0.088	0.09	0.18	3.50E-27	5.63E-26	5.98E-26

211	201	0.084	0.08	0.17	2.55E-27	4.10E-26	4.36E-26

212	202	0.081	0.08	0.16	1.86E-27	2.99E-26	3.18E-26

213	203	0.078	0.08	0.16	1.35E-27	2.18E-26	2.31E-26

214	204	0.075	0.07	0.15	9.85E-28	1.59E-26	1.68E-26

215	205	0.072	0.07	0.14	7.17E-28	1.16E-26	1.23E-26

216	206	0.070	0.07	0.14	5.22E-28	8.42E-27	8.94E-27

217	207	0.067	0.07	0.13	3.80E-28	6.13E-27	6.51E-27

218	208	0.065	0.06	0.13	2.77E-28	4.47E-27	4.74E-27

219	209	0.062	0.06	0.12	2.02E-28	3.25E-27	3.45E-27

220	210	0.060	0.06	0.12	1.47E-28	2.37E-27	2.52E-27

221	211	0.058	0.06	0.11	1.07E-28	1.73E-27	1.83E-27

222	212	0.055	0.06	0.11	7.80E-29	1.26E-27	1.34E-27

223	213	0.053	0.05	0.11	5.68E-29	9.16E-28	9.72E-28

224	214	0.051	0.05	0.10	4.14E-29	6.67E-28	7.08E-28

225	215	0.049	0.05	0.10	3.02E-29	4.86E-28	5.16E-28

226	216	0.047	0.05	0.09	2.20E-29	3.54E-28	3.76E-28

227	217	0.046	0.05	0.09	1.60E-29	2.58E-28	2.74E-28

228	218	0.044	0.04	0.09	1.17E-29	1.88E-28	1.99E-28

229	219	0.042	0.04	0.08	8.49E-30	1.37E-28	1.45E-28

230	220	0.041	0.04	0.08	6.18E-30	9.96E-29	1.06E-28

231	221	0.039	0.04	0.08	4.50E-30	7.26E-29	7.71E-29

232	222	0.038	0.04	0.08	3.28E-30	5.29E-29	5.61E-29

233	223	0.036	0.04	0.07	2.39E-30	3.85E-29	4.09E-29

234	224	0.035	0.03	0.07	1.74E-30	2.80E-29	2.98E-29

235	225	0.034	0.03	0.07	1.27E-30	2.04E-29	2.17E-29

236	226	0.032	0.03	0.06	9.23E-31	1.49E-29	1.58E-29

237	227	0.031	0.03	0.06	6.73E-31	1.08E-29	1.15E-29

238	228	0.030	0.03	0.06	4.90E-31	7.89E-30	8.38E-30

239	229	0.029	0.03	0.06	3.57E-31	5.75E-30	6.11E-30

240	230	0.028	0.03	0.06	2.60E-31	4.19E-30	4.45E-30

241	231	0.027	0.03	0.05	1.89E-31	3.05E-30	3.24E-30

242	232	0.026	0.03	0.05	1.38E-31	2.22E-30	2.36E-30

243	233	0.025	0.02	0.05	1.00E-31	1.62E-30	1.72E-30

244	234	0.024	0.02	0.05	7.32E-32	1.18E-30	1.25E-30

245	235	0.023	0.02	0.05	5.33E-32	8.59E-31	9.12E-31

246	236	0.022	0.02	0.04	3.88E-32	6.26E-31	6.64E-31

247	237	0.021	0.02	0.04	2.83E-32	4.56E-31	4.84E-31

248	238	0.020	0.02	0.04	2.06E-32	3.32E-31	3.53E-31

249	239	0.020	0.02	0.04	1.50E-32	2.42E-31	2.57E-31

250	240	0.019	0.02	0.04	1.09E-32	1.76E-31	1.87E-31

251	241	0.018	0.02	0.04	7.96E-33	1.28E-31	1.36E-31

252	242	0.017	0.02	0.03	5.80E-33	9.34E-32	9.92E-32

253	243	0.017	0.02	0.03	4.22E-33	6.81E-32	7.23E-32

254	244	0.016	0.02	0.03	3.08E-33	4.96E-32	5.27E-32

255	245	0.016	0.02	0.03	2.24E-33	3.61E-32	3.84E-32

256	246	0.015	0.01	0.03	1.63E-33	2.63E-32	2.79E-32

257	247	0.014	0.01	0.03	1.19E-33	1.92E-32	2.03E-32

258	248	0.014	0.01	0.03	8.66E-34	1.40E-32	1.48E-32

259	249	0.013	0.01	0.03	6.31E-34	1.02E-32	1.08E-32

260	250	0.013	0.01	0.03	4.60E-34	7.40E-33	7.86E-33

261	251	0.012	0.01	0.02	3.35E-34	5.39E-33	5.73E-33

262	252	0.012	0.01	0.02	2.44E-34	3.93E-33	4.17E-33

263	253	0.011	0.01	0.02	1.78E-34	2.86E-33	3.04E-33

264	254	0.011	0.01	0.02	1.29E-34	2.08E-33	2.21E-33

265	255	0.011	0.01	0.02	9.42E-35	1.52E-33	1.61E-33

266	256	0.010	0.01	0.02	6.86E-35	1.11E-33	1.17E-33

267	257	0.010	0.01	0.02	5.00E-35	8.06E-34	8.56E-34

268	258	0.009	0.01	0.02	3.64E-35	5.87E-34	6.23E-34

269	259	0.009	0.01	0.02	2.65E-35	4.27E-34	4.54E-34

270	260	0.009	0.01	0.02	1.93E-35	3.11E-34	3.31E-34

271	261	0.008	0.01	0.02	1.41E-35	2.27E-34	2.41E-34

272	262	0.008	0.01	0.02	1.03E-35	1.65E-34	1.75E-34

273	263	0.008	0.01	0.02	7.47E-36	1.20E-34	1.28E-34

274	264	0.008	0.01	0.01	5.44E-36	8.76E-35	9.31E-35

275	265	0.007	0.01	0.01	3.96E-36	6.38E-35	6.78E-35

276	266	0.007	0.01	0.01	2.89E-36	4.65E-35	4.94E-35

277	267	0.007	0.01	0.01	2.10E-36	3.39E-35	3.60E-35

278	268	0.006	0.01	0.01	1.53E-36	2.47E-35	2.62E-35

279	269	0.006	0.01	0.01	1.12E-36	1.80E-35	1.91E-35

280	270	0.006	0.01	0.01	8.12E-37	1.31E-35	1.39E-35

281	271	0.006	0.01	0.01	5.92E-37	9.53E-36	1.01E-35

282	272	0.006	0.01	0.01	4.31E-37	6.94E-36	7.38E-36

283	273	0.005	0.01	0.01	3.14E-37	5.06E-36	5.37E-36

284	274	0.005	0.01	0.01	2.29E-37	3.68E-36	3.91E-36

285	275	0.005	0.00	0.01	1.67E-37	2.68E-36	2.85E-36

286	276	0.005	0.00	0.01	1.21E-37	1.96E-36	2.08E-36

287	277	0.005	0.00	0.01	8.84E-38	1.42E-36	1.51E-36

288	278	0.004	0.00	0.01	6.44E-38	1.04E-36	1.10E-36

289	279	0.004	0.00	0.01	4.69E-38	7.56E-37	8.02E-37

290	280	0.004	0.00	0.01	3.42E-38	5.50E-37	5.85E-37

291	281	0.004	0.00	0.01	2.49E-38	4.01E-37	4.26E-37

292	282	0.004	0.00	0.01	1.81E-38	2.92E-37	3.10E-37

293	283	0.004	0.00	0.01	1.32E-38	2.13E-37	2.26E-37

294	284	0.003	0.00	0.01	9.62E-39	1.55E-37	1.65E-37

295	285	0.003	0.00	0.01	7.00E-39	1.13E-37	1.20E-37

296	286	0.003	0.00	0.01	5.10E-39	8.22E-38	8.73E-38

297	287	0.003	0.00	0.01	3.72E-39	5.99E-38	6.36E-38

298	288	0.003	0.00	0.01	2.71E-39	4.36E-38	4.63E-38

299	289	0.003	0.00	0.01	1.97E-39	3.18E-38	3.37E-38

300	290	0.003	0.00	0.01	1.44E-39	2.31E-38	2.46E-38

301	291	0.003	0.00	0.01	1.05E-39	1.69E-38	1.79E-38

302	292	0.003	0.00	0.01	7.62E-40	1.23E-38	1.30E-38

303	293	0.002	0.00	0.005	5.55E-40	8.94E-39	9.50E-39

304	294	0.002	0.00	0.0047	4.04E-40	6.51E-39	6.92E-39

305	295	0.002	0.00	0.0046	2.95E-40	4.74E-39	5.04E-39

306	296	0.002	0.00	0.0044	2.15E-40	3.46E-39	3.67E-39

307	297	0.002	0.00	0.0042	1.56E-40	2.52E-39	2.67E-39

308	298	0.002	0.00	0.0041	1.14E-40	1.83E-39	1.95E-39

309	299	0.002	0.00	0.0039	8.29E-41	1.34E-39	1.42E-39

310	300	0.002	0.00	0.0038	6.04E-41	9.73E-40	1.03E-39

311	301	0.002	0.00	0.0036	4.40E-41	7.09E-40	7.53E-40

312	302	0.002	0.00	0.0035	3.20E-41	5.16E-40	5.48E-40

313	303	0.002	0.00	0.0034	2.33E-41	3.76E-40	3.99E-40

314	304	0.002	0.00	0.0032	1.70E-41	2.74E-40	2.91E-40

315	305	0.002	0.00	0.0031	1.24E-41	2.00E-40	2.12E-40

316	306	0.001	0.00	0.0030	9.02E-42	1.45E-40	1.54E-40

317	307	0.001	0.00	0.0029	6.57E-42	1.06E-40	1.12E-40

318	308	0.001	0.00	0.0028	4.79E-42	7.71E-41	8.19E-41

319	309	0.001	0.00	0.0027	3.49E-42	5.62E-41	5.96E-41

320	310	0.001	0.00	0.0026	2.54E-42	4.09E-41	4.34E-41

321	311	0.001	0.00	0.0025	1.85E-42	2.98E-41	3.16E-41

322	312	0.001	0.00	0.0024	1.35E-42	2.17E-41	2.31E-41

323	313	0.001	0.00	0.0023	9.81E-43	1.58E-41	1.68E-41

324	314	0.001	0.00	0.0022	7.15E-43	1.15E-41	1.22E-41

325	315	0.001	0.00	0.0021	5.21E-43	8.39E-42	8.91E-42

326	316	0.001	0.00	0.0020	3.79E-43	6.11E-42	6.49E-42

327	317	0.001	0.00	0.0020	2.76E-43	4.45E-42	4.73E-42

328	318	0.001	0.00	0.0019	2.01E-43	3.24E-42	3.44E-42

329	319	0.001	0.00	0.0018	1.47E-43	2.36E-42	2.51E-42

330	320	0.001	0.00	0.0017	1.07E-43	1.72E-42	1.83E-42

331	321	0.001	0.00	0.0017	7.78E-44	1.25E-42	1.33E-42

332	322	0.001	0.00	0.0016	5.66E-44	9.13E-43	9.69E-43

333	323	0.001	0.00	0.0016	4.13E-44	6.65E-43	7.06E-43

334	324	0.001	0.00	0.0015	3.01E-44	4.84E-43	5.14E-43

335	325	0.001	0.00	0.0014	2.19E-44	3.53E-43	3.75E-43

336	326	0.001	0.00	0.0014	1.59E-44	2.57E-43	2.73E-43

337	327	0.001	0.00	0.0013	1.16E-44	1.87E-43	1.99E-43

338	328	0.001	0.00	0.0013	8.46E-45	1.36E-43	1.45E-43

339	329	0.001	0.00	0.0012	6.16E-45	9.93E-44	1.05E-43

340	330	0.001	0.00	0.0012	4.49E-45	7.23E-44	7.68E-44

341	331	0.001	0.00	0.0011	3.27E-45	5.27E-44	5.59E-44

342	332	0.001	0.00	0.0011	2.38E-45	3.84E-44	4.08E-44

343	333	0.001	0.00	0.0011	1.73E-45	2.79E-44	2.97E-44

344	334	0.001	0.00	0.0010	1.26E-45	2.04E-44	2.16E-44

345	335	0.000	0.00	0.0010	9.20E-46	1.48E-44	1.57E-44

346	336	0.000	0.00	0.0009	6.70E-46	1.08E-44	1.15E-44

347	337	0.000	0.00	0.0009	4.88E-46	7.87E-45	8.36E-45

348	338	0.000	0.00	0.0009	3.56E-46	5.73E-45	6.09E-45

349	339	0.000	0.00	0.0008	2.59E-46	4.17E-45	4.43E-45

350	340	0.000	0.00	0.0008	1.89E-46	3.04E-45	3.23E-45

351	341	0.000	0.00	0.0008	1.37E-46	2.21E-45	2.35E-45

352	342	0.000	0.00	0.0008	1.00E-46	1.61E-45	1.71E-45

353	343	0.000	0.00	0.0007	7.29E-47	1.18E-45	1.25E-45

354	344	0.000	0.00	0.0007	5.31E-47	8.56E-46	9.09E-46

355	345	0.000	0.00	0.0007	3.87E-47	6.23E-46	6.62E-46

356	346	0.000	0.00	0.0006	2.82E-47	4.54E-46	4.82E-46

357	347	0.000	0.00	0.0006	2.05E-47	3.31E-46	3.51E-46

358	348	0.000	0.00	0.0006	1.50E-47	2.41E-46	2.56E-46

359	349	0.000	0.00	0.0006	1.09E-47	1.76E-46	1.86E-46

360	350	0.000	0.00	0.0006	7.94E-48	1.28E-46	1.36E-46

361	351	0.000	0.00	0.0005	5.78E-48	9.31E-47	9.89E-47

362	352	0.000	0.00	0.0005	4.21E-48	6.78E-47	7.20E-47

363	353	0.000	0.00	0.0005	3.07E-48	4.94E-47	5.25E-47

364	354	0.000	0.00	0.0005	2.23E-48	3.60E-47	3.82E-47

365	355	0.000	0.00	0.0005	1.63E-48	2.62E-47	2.78E-47

366	356	0.000	0.00	0.0004	1.19E-48	1.91E-47	2.03E-47

367	357	0.000	0.00	0.0004	8.63E-49	1.39E-47	1.48E-47

368	358	0.000	0.00	0.0004	6.29E-49	1.01E-47	1.08E-47

369	359	0.000	0.00	0.0004	4.58E-49	7.38E-48	7.84E-48

370	360	0.000	0.00	0.0004	3.34E-49	5.38E-48	5.71E-48

371	361	0.000	0.00	0.0004	2.43E-49	3.92E-48	4.16E-48

372	362	0.000	0.00	0.0003	1.77E-49	2.85E-48	3.03E-48

373	363	0.000	0.00	0.0003	1.29E-49	2.08E-48	2.21E-48

374	364	0.000	0.00	0.0003	9.39E-50	1.51E-48	1.61E-48

375	365	0.000	0.00	0.0003	6.84E-50	1.10E-48	1.17E-48

376	366	0.000	0.00	0.0003	4.98E-50	8.03E-49	8.53E-49

377	367	0.000	0.00	0.0003	3.63E-50	5.85E-49	6.21E-49

378	368	0.000	0.00	0.0003	2.64E-50	4.26E-49	4.52E-49

379	369	0.000	0.00	0.0003	1.93E-50	3.10E-49	3.30E-49

380	370	0.000	0.00	0.0003	1.40E-50	2.26E-49	2.40E-49

381	371	0.000	0.00	0.0002	1.02E-50	1.65E-49	1.75E-49

382	372	0.000	0.00	0.0002	7.44E-51	1.20E-49	1.27E-49

  

  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:Cyhalofop residues

 time is 10/ 3/2008  17:39:37

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.230           2.0           0.460      3.50E+01       21.0

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

 groundwater screening cond (ppb) =   1.52E-01 

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

 

 Maximum single application rate = (15 ounces (oz.) product per A/128
oz. per gallon) x 2.38 lbs a.i. per gallon as stated on label

 Maximum seasonal application rate = (25 oz. product per A/128 oz per
gallon) x 2.38 lbs a.i. per gallon as stated on label

 PP#0F06089.  New Chemical:  Cyhalofop-Butyl in/on Rice.  Decision
Memorandum of the HED Metabolism Assessment Review Committee. (Memo from
M. Nelson to Y. Donovan, November 13, 2001, DP Barcode:  D277192).

 USDA, 2008 County Crop Programs available at: 
http://www.rma.usda.gov/data/cropprograms/2008/0018T.pdf (accessed
September 24, 2008).

 USDA, 2008 County Crop Programs available at:    HYPERLINK
"http://www.rma.usda.gov/data/cropprograms/2008/0055T.pdf" 
http://www.rma.usda.gov/data/cropprograms/2008/0055T.pdf  (accessed
September 24, 2008).

 PP#0F06089.  New Chemical:  Cyhalofop-Butyl in/onRice.  Decision
Memorandum of the HED Metabolism Assessment Review Committee. (Memo from
M. Nelson to Y. Donovan, November 13, 2001, DP Barcode:  D277192).

 While modeling an application preflood with an application postflood
predicted lower residues in paddy water, the aquatic dissipation studies
measured higher residues in this scenario (USEPA, 2001a; MRID 45000520).
 Additionally, modeling of flooded applications predicted residues
similar to those measured in the aquatic dissipation studies when
preflood applications were present.  Therefore, flooded applications
were assumed for modeling.

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

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

 PAGE   

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-

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-  PAGE  6  of   NUMPAGES  62 -