UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

	OFFICE OF PREVENTION, PESTICIDE

	AND TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:  27 October 2009

SUBJECT:	Clopyralid – Petition for Tolerances on Swiss chard,
Bushberry Subgroup 13-07B, and Strawberry (Regional Restriction). 
Summary of Analytical Chemistry and Residue Data.

PC Code:  117401 (alkanolamine salts), 117403 (acid)	DP Barcode: 
D361787

Decision No.:  403248	Registration Nos.:  62719-80, 62719-81, and
62719-84

Petition No.:  8E7481	Regulatory Action:  Section 3 and 24(c)
Registrations

Risk Assessment Type:  NA	Case No.:  NA

TXR No.:  NA	CAS Nos.:	1702-17-6 (acid)

	57754-85-5 (monoethanolamine salt)

MRID No.:  See MRID Summary Table	40 CFR:  180.431 

		              									

FROM:	Michael A. Doherty, Ph.D., Chemist  SEQ CHAPTER \h \r 1 

		Risk Assessment Branch II

		Health Effects Division (7509P)

THROUGH:	William Drew, Chemist

		Risk Assessment Branch II

		Health Effects Division (7509P)

TO:		  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 Barbara Madden, RM 05

		Risk Integration, Minor Use & Emergency Response Branch

		Registration Division (7505P)

		

MRID Summary Table

MRID No.	Study Type	Comments

47604401	860.1500 Swiss chard	New DER 47604401.der

47604402	860.1500 blueberry	New DER 47604402.der

47604403	860.1500 strawberry	New DER 47604403.der



  SEQ CHAPTER \h \r 1 This document was originally prepared under
contract by Dynamac Corporation (1910 Sedwick Road, Building 100, Suite
B; Durham, NC 27713).  The document has been reviewed by the Health
Effects Division (HED) and revised to reflect current Office of
Pesticide Programs (OPP) policies.

Executive Summary

Clopyralid [3,6-dichloro-2-pyridinecarboxylic acid]  is a pyridine
herbicide registered for use on a variety of food and feed crops in the
U.S. for the postemergence control of broadleaf weeds, particularly
thistles and clover.  Permanent tolerances are established for residues
of clopyralid in/on a wide variety of plant commodities at levels
ranging from 0.5 ppm in/on stone fruits to 500 ppm in/on grass forage
and hay [40 CFR §180.431(a)], including a tolerance of 1.0 ppm for
strawberry.  Permanent tolerances are also established for residues of
clopyralid in livestock commodities at levels ranging from 0.1 ppm in
eggs to 36 ppm in meat byproducts, except liver, of cattle, goats,
horses and sheep.  There currently are no tolerances for inadvertent or
indirect residues of clopyralid. 

The Interregional Project No. 4 (IR-4) has submitted a petition
proposing the use of the 3 lb acid equivalent (ae)/gal emulsifiable
concentrate (EC) formulation of the monoethanolamine salt of clopyralid
(Stinger®; EPA Reg. No. 62719-73) on Swiss chard, members of the
bushberry subgroup (13-07B), and strawberries (FL and NC only).  The
proposed use on Swiss chard is for a single broadcast foliar application
no later than the 8-leaf stage at 0.094-0.187 lb ae/A, and the proposed
use on bushberries is for two soil-directed applications beginning one
week after bloom at up to 0.25 lb ae/A/application for a maximum of 0.5
lb ae/A/season, with a minimum retreatment interval (RTI) of 14 days. 
The proposed use on strawberries is for a single broadcast foliar
application at 0.113-0.25 lb ae/A at up to 7 days prior to harvest; this
use is restricted to strawberries grown in FL and NC under an
annual-type production system.  All uses allow for applications using
only ground equipment.  The proposed minimum preharvest intervals (PHIs)
are 30 days for Swiss chard and bushberries, and 7 days for
strawberries.  In conjunction with the proposed uses on Swiss chard and
bushberries, IR-4 is proposing the following permanent tolerances for
clopyralid:

Swiss chard	5.0 ppm

Bushberry subgroup 13-07B	6.0 ppm

For the proposed use on strawberries, IR-4 is proposing the following
permanent tolerance for clopyralid with a regional restriction:

Strawberry (annual)	4.0 ppm

Based on the available cabbage, grass, wheat and barley metabolism
studies, the nature of clopyralid residues in plants is adequately
understood for purposes of this petition.  The residue of concern in
plants for both risk assessment and the tolerance expression is
clopyralid. 

As the crop uses being proposed in this petition do not include any
regulated livestock feedstuffs, issues pertaining to residues in
livestock commodities are not relevant to the current petition.

An adequate gas chromatograph/electron-capture detection (GC/ECD) method
(Method ACR 75.6) is available for enforcing tolerances for clopyralid
in/on plant commodities.  In the submitted Swiss chard, blueberry and
strawberry field trials, residues of clopyralid in/on each commodity
were determined using a slightly modified version of the current
enforcement method.  The method was adequately validated in conjunction
with the analysis of field trial samples, and the lowest level of method
validation (LLMV) was 0.05 ppm for each crop.  

The submitted Swiss chard, blueberry and strawberry field trial data are
adequate and support the proposed uses.  An adequate number of tests
were conducted on each crop in the appropriate geographic regions at ~1x
the maximum proposed rate, and the appropriate samples were collected
from each test around the proposed PHI.  Residues of clopyralid in/on
each commodity were determined using an adequate GC/ECD method, and the
duration and conditions of sample storage are supported by the available
storage stability data.  The available field trial data support
tolerances of 3.0 ppm for Swiss chard, 0.50 ppm for the bushberry
subgroup 13-07B, and 4.0 ppm for strawberries.

No processing data are required to support the proposed uses, and the
existing confined rotational crop study adequately supports the
rotational crop restrictions specified on the current label.

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

Provided the label is modified to exclude use on low-growing varieties
of bushberry, there are no deficiencies in the subject petition that
would preclude establishing permanent tolerances for residues of
clopyralid on the proposed commodities.  The residue chemistry data
support tolerances for clopyralid at 3.0 ppm in/on Swiss chard and at
0.50 ppm in/on the bushberry subgroup 13-07B, except low-bush varieties.
 Based on the available data, the existing tolerance of 1.0 ppm in/on
strawberry should be increased to 4.0 ppm to support the proposed use
pattern in FL and NC (see Table 6).  HED notes that although a tolerance
for the bushberry subgroup 13-07B would include cranberry, the existing
tolerance for residues in/on cranberry should remain due to use pattern
differences between cranberry and the bushberry subgroup.  HED notes
that the recommended tolerances on bushberry and strawberry are not
harmonized with Canadian MRLs.  There are no residue chemistry
considerations that would preclude granting the regional registrations
for clopyralid.  A human health risk assessment for clopyralid is
forthcoming.  The tolerance definition for clopyralid should be revised
to read as follows:

Tolerances are established for residues of the herbicide clopyralid,
including its metabolites and degradates, in or on the commodities in
the table below as a result of the application of clopyralid. 
Compliance with the tolerance levels specified below is to be determined
by measuring only clopyralid [3,6-dichloro-2-pyridinecarboxylic acid] in
or on the commodity.

Background

Clopyralid is a selective, postemergence pyridine herbicide that is used
for the control of broadleaf weeds, particularly thistles and clover, in
a variety of crops.  In the current petition (PP#8E7481), IR-4 is
proposing to expand the use of clopyralid to include applications to
Swiss chard and bushberries for the postemergence control of various
weeds.  In addition, IR-4 is proposing a regionally restricted use on
strawberries grown only in FL and NC under an annual-type production
system.  There is currently a use on strawberries grown as a perennial
crop (DP# 270507, 8/6/2002, D. Dotson).  The chemical structure and
nomenclature of the monoethanolamine salt of clopyralid is summarized in
Table 1, and the physicochemical properties of clopyralid are summarized
in Table 2.  

Table1.	Clopyralid Nomenclature.

Compound	

Common name	Clopyralid, monoethanolamine salt

Company experimental name	Dowco 290

IUPAC name	3,6-dichloropyridine-2-carboxylic acid, monoethanolamine salt

CAS name	3,6-dichloro-2-pyridinecarboxylic acid, monoethanolamine salt

CAS registry number	1702-17-6 (acid)

57754-85-5 (monoethanolamine salt)

End-use product (EP)	3 lb ae/gal EC (Stinger® herbicide; EPA Reg. No.
62719-73)



Table 2.	Physicochemical Properties of Technical Grade Clopyralid Acid.

Parameter	Value	Reference

Melting point/range	149.6	Data were obtained from the FOOTPRINT
Pesticide Properties DataBase, (  HYPERLINK
"http://www.eu-footprint.org/ppdb.html" 
http://www.eu-footprint.org/ppdb.html ).



pH	Not available

	Density (specific gravity)	1.76 g/mL

	Water solubility (g/L) at 20°C	143

	Solvent solubility (g/L) at 20°C	Acetone – 250

Ethyl acetate – 102

Xylene – 4.6

Hexane – 6.0

	Vapor pressure at 25°C, mPa	1.36

	Dissociation constant, pKa, at 25°C	2.01

	Octanol/water partition coefficient, Log(KOW), at 20°C	-2.63

	UV/visible absorption spectrum	Not available

	

860.1200  Directions for Use

A 3.0 lb ae/gal EC formulation of clopyralid is currently registered to
Dow AgroSciences (Stinger®; EPA Reg. No. 62719-73) for use on a wide
variety of crops for the postemergence control of weeds.   IR-4 is
proposing new uses for this formulation on Swiss chard and members of
the bushberry subgroup.  Although there is an existing use for
clopyralid on perennial strawberries, with a 30-day PHI, IR-4 is also
proposing to establish a new use for strawberries grown under an annual
production system in the states of NC and FL.  Examples of supplemental
labels for the 3 lb ae/gal EC were provided, and the proposed use
directions are summarized below in Table 3.

Table 3.	Summary of Directions for Use of Clopyralid.

Applic. Timing, Type, and Equip. 1	Formulation

[EPA Reg. No.]	Applic. Rate 

(lb ae/A)	Max. No. Applic. per Season	Max. Seasonal Applic. Rate

(lb ae/A)	PHI

(days)	Use Directions and Limitations 2

Swiss Chard

Broadcast foliar application when crop is at the cotyledon to 8-leaf
stage of growth; ground equipment.	3.0 lb ae/gal EC [62719-73]
0.094-0.187	1	0.187	30	Apply in a minimum of 10 gal/A

Bushberry subgroup 13-07B

Directed applications to row middles beginning 1 week after bloom;
ground equipment 	3.0 lb ae/gal EC [62719-73]	0.06-0.25	2	0.5	30	Apply
in a minimum of 10 gal/A, with a minimum RTI of 14 days.  Do not apply
by aircraft.

Strawberry (annual fields only in FL and NC)

Broadcast foliar application to well-established plantings; ground
equipment	3.0 lb ae/gal EC [62719-73]	0.113-0.25	1	0.25	7	Apply in a
minimum of 20 gal/A.  Do not use with a surfactant.

Do not apply by aircraft

1	Do not apply through any type of irrigation system.

2	The label for the 3 lb ae/gal EC contains the following rotational
crop restrictions:  barley, canola, cole crops, flax, garden beets,
grasses, corn (field, pop and sweet), oats, spinach, sugar beets,
turnips and wheat may be planted at anytime following a treated crop. 
Depending on the amount of soil organic matter, rainfall and location
(state), the plant-back intervals for all other crops range from 10.5 to
18 months.

Conclusions.  The labels are adequate to allow evaluation of the residue
data relative to the proposed uses.  The available field trial data
support the proposed use directions, although the label should be
revised to exclude use on low-growing varieties of bushberry.  

860.1300 Nature of the Residue - Plants

DP# 270507, 8/6/2002, D. Dotson

The nature of the residue in plants is adequately understood for
purposes of this petition based on the acceptable cabbage, grass, barley
and wheat metabolism studies.  In each of these studies, the major
14C-residue was determined to be only parent compound.  Although data
are available for only two dissimilar crops (leafy vegetable and cereal
grain), HED has concluded that the residue of concern in plants for
purposes of this petition is clopyralid.  However, the Agency reserves
the right to require additional metabolism studies in the future should
the petitioner request the establishment of clopyralid tolerances for
additional crops. 

860.1300 Nature of the Residue - Livestock

There are no livestock feedstuffs associated with the proposed use on
Swiss chard, bushberry subgroup 13-07B, and strawberry.  Therefore, data
requirements for livestock metabolism are not relevant to this tolerance
petition.

860.1340 Residue Analytical Methods

Enforcement method.  The Pesticide Analytical Manual (PAM) Vol. II lists
a GC/ECD method for determining residues of clopyralid residues in/on
plant commodities (Method I or Method ACR 75.6).

For this method, residues are extracted with dilute NaOH (0.25% or 0.1%)
and filtered.  The extract is then acidified and salinized, and residues
are partitioned into ethyl ether.  Residues are then methylated using
diazomethane and cleaned up on an activated Alumina column.  Residues
are then determined by GC/ECD using external standards.  The reported
LOQs are 0.5 ppm for grains and 2.0 ppm for green forage.

Data collection methods.  In the submitted field trials, residues of
clopyralid in/on samples of Swiss chard, blueberries and strawberries
were determined using a slightly modified version of the current
tolerance enforcement method.

For each commodity, residues were extracted with 0.5% NaOH and
centrifuged.  The resulting extract was acidified with HCl and salinized
with NaCl, and residues were partitioned into ethyl ether.  Residues
were then methylated using diazomethane, concentrated to dryness,
re-dissolved in toluene, and cleaned up using an activated Alumina A
column eluted with toluene.  The methylated residues were analyzed by
GC/ECD using external standards.  Residues are expressed in terms of
parent clopyralid using a conversion factor of 0.93.  The lowest level
of method validation (LLMV) for clopyralid in each commodity was 0.05
ppm.  The calculated LOQs were 0.052-0.073 ppm and the LODs were
0.017-0.024 ppm.

The above method was adequately validated using control samples of each
matrix fortified with clopyralid at 0.05-5.0 ppm.  Acceptable recoveries
were obtained for each matrix, and the fortification levels bracketed
the measured residue levels.  Apparent residues of clopyralid were <LOQ
in/on control samples, which the exception of two control samples from
one of the blueberry field trials which had apparent residues of
clopyralid at 0.060 and 0.055 ppm.

Conclusions.  An adequate GC/ECD method (Method ACR 75.6) is available
for enforcing the proposed tolerances and collecting data on residues of
clopyralid in Swiss chard, blueberries and strawberries.

860.1360 Multiresidue Methods

The FDA Pestrak database (PAM Vol. I, Appendix dated 11/6/90) indicates
that the existing FDA multiresidue methods are not likely to recover
clopyralid.  HED notes that clopyralid does appear to be adequately
recovered by the “QuEChERS” multiresidue method
(http://www.quechers.com).

860.1380 Storage Stability

DP# 270507, 8/6/2002, D. Dotson

Under frozen storage conditions, clopyralid has been shown to be stable
in plant commodities for the following durations: 50 months in safflower
seeds, soybeans, sugar beet roots and tops, and oat forage, grain and
straw; 30 months in strawberries; 26 months in dried hops cones; 16
months in cherries and plums; 15 months in canola meal; 10 months in
canola seed and oil; 9 months in cabbage and spinach; 5 months in
mustard greens; and 3 months in peaches.

Samples collected from the submitted field trials were stored frozen
within 3 hours after harvest, shipped frozen to the analytical
laboratory 2-40 days later, and stored at -21°C at the analytical
laboratory until analysis.  The maximum frozen storage intervals, from
harvest to analysis of samples, are listed in Table 4.

Table 4.	Summary of Storage Conditions and Durations of Samples from
Crop Field Trial Studies.  

Matrix 	Storage Temperature  (°C)	Actual Storage Duration (days)
Interval of Demonstrated Storage Stability (months)

Swiss Chard	-21 ± 7	41-91	5 (Mustard Greens)

Blueberry	-21 ± 7	41-132	16 (Cherry)

Strawberry	-21 ± 7	90-99	30 (Strawberry)



Conclusions.  Adequate storage stability data are available to support
the sample storage conditions and durations in the submitted field
trials.

860.1400 Water, Fish, and Irrigated Crops

There are no proposed uses that are relevant to this guideline topic.

860.1460 Food Handling

There are no proposed uses that are relevant to this guideline topic.

860.1480 Meat, Milk, Poultry, and Eggs

There are no livestock feedstuffs associated with the proposed use on
Swiss chard, bushberry subgroup 13-07B and strawberry.  Therefore, data
requirements pertaining to meat, milk, poultry, and eggs are not
relevant to this tolerance petition.

860.1500 Crop Field Trials

47604401.der (Swiss Chard)

47604402.der (blueberry)

47604403.der (strawberry)

IR-4 has submitted new field trial data supporting the proposed uses of
clopyralid (3 lb ae/gal EC) on Swiss chard and members of the bushberry
subgroup 13-07B.  Although there is an existing use for clopyralid on
strawberries grown under a perennial cropping system, IR-4 is requesting
a new use on strawberries grown in FL and NC under an annual production
system.  New strawberry field trial data have been submitted to support
this new use.    SEQ CHAPTER \h \r 1 The results from these field trials
are discussed below and the residue data are summarized in Table 5.

Table 5.	Summary of Residue Data from Crop Field Trials with Clopyralid
(EC).

Crop matrix	Total Applic. Rate  (lb ae/A)	PHI (days)	Residue Levels
(ppm) 1



	n	Min.	Max.	HAFT 1	Median	Mean	Std. Dev.

Swiss Chard (proposed use = 0.187 lb ae/A total application rate, 30-day
PHI)

Swiss Chard	0.093-0.103	28-29	8	0.05	0.70	0.62	0.34	0.34	0.22

	0.188-0.199

8	<0.05	1.90	1.60	0.57	0.69	0.69

Bushberry subgroup 13-07B (proposed use = 0.5 lb ae/A total application
rate, 30-day PHI)

Blueberry 3	0.483-0.525	27-33	14	<0.05	0.42	0.38	0.06	0.12	0.12

Strawberry, grown in FL and NC only  (proposed use = 0.25 lb ae/A total
application rate, 7-day PHI)

Strawberry	0.119-0.125	7-8	6	0.79	1.80	1.70	0.98	1.18	0.42

	0.246-0.255

6	1.60	3.00	2.85	2.40	2.35	0.53

1	Residues are expressed in terms for clopyralid acid.  The LLMV for
clopyralid was 0.05 ppm.  For all calculations, 0.05 ppm was used for
any residue values <LLMV.

2	HAFT = Highest Average Field Trial.

3  Residues from the field trial in ME, which used a foliar application,
have not been included in the summary of residue data.

Swiss Chard.  Four field trials were conducted on Swiss chard in Zones
1, 2 and 11 during the 2002 growing season.  In side-by-side tests at
each site, the monoethanolamine salt of clopyralid (3.0 lb ae/gal EC)
was applied to Swiss chard as a single broadcast foliar application
during vegetative development at rates of 0.093-0.103 lb ae/A or
0.188-0199 lb ae/A (0.5 and 1.0x the proposed rate).  Applications were
made using ground equipment in volumes of 16-60 gal/A, without the use
of a spray adjuvant.  Single control and duplicate treated samples of
Swiss chard (leaves and petioles) were harvested from each plot at
commercial maturity, 28-29 days after treatment (DAT).  

Samples were stored at ≤-21°C for up to 3 months from harvest to
analysis; a duration that is supported by the available storage
stability data.  Samples were analyzed for residues of clopyralid using
an adequate GC/ECD method, which is a slightly modified version of the
current tolerance enforcement method (Method ACR 79.5).  The lowest
level of method LLMV for clopyralid in Swiss chard was 0.05 ppm.

Following a single broadcast foliar application of clopyralid (EC),
residues in/on Swiss chard harvested at 28-29 DAT were 0.05-0.70 ppm at
the 0.5x rate and <0.05-1.90 ppm at the 1x rate.  For the 0.5x and 1x
use rates, average residues were 0.34 and 0.69 ppm, respectively, and
the HAFT residues were 0.62 and 1.60 ppm.  A residue decline study was
not conducted.

Bushberry Subgroup 13-07.  Nine blueberry field trials were conducted in
Zones 1, 2, 5 and 12 during the 1999 and 2000 growing seasons.  Lowbush
type blueberries were treated at the one test site in ME (Zone 1), and
highbush type blueberries were treated at all the other test sites.  At
each site, the monoethanolamine salt of clopyralid (3 lb ae/gal) was
applied to blueberries as two applications during early fruit
development at rates of 0.240-0.264 lb ae/A, for a total rate of
0.490-0.525 lb ae/A/season (1x proposed rate).  For the lowbush
blueberry test, the two applications were made as broadcast foliar
applications.  For the highbush blueberry tests, the two applications
were made as directed applications to the ground between the crop rows,
avoiding contact with the bushes.  Applications were made at RTIs of
12-21 using ground equipment in volumes of 20-31 gal/A, without the use
of a spray adjuvant.  Single control and duplicate treated samples were
harvested from each site at commercial maturity, 27-33 DAT.

at ≤-21°C for up to 4.3 months from harvest to analysis; an interval
that is supported by the available storage stability data.  Samples were
analyzed for residues of clopyralid using an adequate GC/ECD method,
which is a slightly modified version of the current tolerance
enforcement method (Method ACR 79.5).  The LLMV for clopyralid in
blueberries was 0.05 ppm.

 

The residue data from one of the tests (Trial MI16) were excluded from
the dataset because clopyralid residues were found in controls samples
at levels similar to the residue levels in the associated treated
samples.  These data were not used in determining a recommended
tolerance level (see Appendix II).

Following two broadcast foliar application of clopyralid (EC) totaling
0.49 lb ae/A, residues were 4.7 and 5.8 ppm in/on blueberries harvested
at 28 DAT.  Following soil-directed application at rates ranging from
0.48 to 0.53 lb ae/A, residues were <0.05 – 0.42 ppm in/on blueberries
harvested 27-33 DAT.  Not including the foliar treatment, the average
residue was 0.11 pm and the highest average field trail (HAFT) residue
was 0.38 ppm.  A residue decline study was not conducted.

Strawberry (annual production system in FL and NC only).  Three field
trials were conducted in Zones 2 and 3 during the 2002 growing season on
strawberries growing in an annual-type production system.  In
side-by-side tests at each site, the monoethanolamine salt of clopyralid
(3.0 lb ae/gal EC) was applied to strawberries as a single broadcast
foliar application during fruiting at rates of 0.119-0.125 lb ae/A or
0.246-0.255 lb ae/A (0.5x and 1x the proposed use rate).  Applications
were made using ground equipment in volumes of 29-35 gal/A, without the
use of a spray adjuvant.  Single control and duplicate treated samples
of strawberries were harvested from each plot at commercial maturity,
7-8 DAT.

Samples were stored at ≤-21°C for up to 3 months from harvest to
analysis; a duration that is supported by the available storage
stability data.  Samples were analyzed for residues of clopyralid using
an adequate GC/ECD method, which is a slightly modified version of the
current tolerance enforcement method (Method ACR 79.5).  The LLMV for
clopyralid in strawberries was 0.05 ppm.

Following a single broadcast foliar application of clopyralid (EC),
residues in/on strawberries harvested at 7-8 DAT were 0.079-0.180 ppm at
the 0.5x rate and 1.60-3.00 ppm at the 1x rate.  For the 0.5x and 1x
rates, average residues were 1.18 and 2.35 ppm, respectively, and the
HAFT residues were 1.70 and 2.85 ppm.  A residue decline study was not
conducted. 

Conclusions.  The Swiss chard, blueberry and strawberry field trials are
adequate and support the proposed use patterns.  An adequate number of
tests were conducted in the appropriate geographical regions, and
samples were analyzed for the residue of concern using an adequate data
collection method.  Adequate storage stability data are available to
support the storage conditions incurred in the field trials.  The data
support tolerances of 3.0 ppm in/on Swiss chard and 0.50 ppm in/on
bushberries, provided low-growing varieties are excluded.  The data also
support a 4.0 ppm in/on strawberries, with a regional restriction to FL
and NC.  The label should be revised to prohibit use on low-growing
varieties of bushberries since their morphology does not readily allow
for soil applications.  Furthermore, directions for a previously
established use on cranberry (a member of the bushberry group) are
significantly different than the currently proposed use; therefore, the
existing tolerance for cranberry should remain even if a tolerance for
the bushberry subgroup is established.

860.1520 Processed Food and Feed

HED does not require residue data for any processed commodities
associated with Swiss chard, bushberry subgroup 13-07B, and strawberry. 
Therefore, data requirements for processed food and feed are not
relevant to this tolerance petition.

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

An analytical standard for clopyralid is currently available in the EPA
National Pesticide Standards Repository (personal communication with
Dallas Wright, ACB, 6/12/2009).  

860.1850/1900 Confined and Field Accumulation in Rotational Crops

DP#  193219, 8/4/93, G. Kramer

An acceptable confined rotational crop study is available for
clopyralid.  In this study, the total radioactive residues in/on
representative rotational crop commodities (lettuce, turnips, green
beans, and wheat) were below 0.01 ppm at plant-back intervals of 49-98
days following application of [14C]clopyralid to the soil at 0.29 lb
ae/A (1.17x the maximum seasonal rate for crops which can be rotated).

  

The current label for the 3 lb ae/gal EC of clopyralid allows for the
replanting of the following crops at anytime:  barley, canola, cole
crops, flax, garden beets, grasses, corn (field, pop and sweet), oats,
spinach, sugar beets, turnips and wheat.  The plant-back interval for
all other crops is 10.5 to 18 months depending on the amount of soil
organic matter, rainfall and location (state).

The established rotational crop restrictions are adequate.  Limited
field rotational crop studies are not required, and no tolerances are
required for inadvertent or indirect residues in rotational crops.

860.1550 Proposed Tolerances

Permanent tolerances are established for residues of clopyralid in/on a
wide variety of plant commodities at levels ranging from 0.5 ppm in/on
stone fruits to 500 ppm in/on grass forage and hay [40 CFR
§180.431(a)], including a 4.0 ppm tolerance on cranberry, which is a
member of the bushberry subgroup 13-07B, and a 1.0 ppm tolerance on
strawberry.  Permanent tolerances are also established for residues of
clopyralid per se in livestock commodities at levels ranging from 0.1
ppm in eggs to 36 ppm in meat byproducts, except liver, of cattle,
goats, horses and sheep.  Currently there are no tolerances for
inadvertent or indirect residues of clopyralid.  A summary of the
recommended tolerances for the petition are listed in Table 6.

An adequate number of field trials at ~1x the proposed use rate are
available for Swiss chard and blueberries to support permanent
tolerances on Swiss chard and the bushberry subgroup 13-07B (except
low-growing varieties), of which blueberry is the representative crop. 
An adequate number of strawberry field trials were also conducted in
Zones 2 and 3 at 1x the proposed use rate to support a tolerance with a
regional restriction to NC and FL.  The Agency’s SOP “Guidelines for
Setting Pesticide Tolerances Based on Field Trial Data” were utilized
for determining the appropriate tolerance level for each commodity
(Appendix II).  The recommended tolerances on Swiss chard and the
bushberry subgroup 13-07B (except low-growing varieties) are 3.0 and
0.50 ppm, respectively.  On strawberries, the new use pattern results in
a recommended tolerance of 4.0 ppm.  As previously noted, the current
tolerance for cranberry at 4.0 ppm should remain even if tolerances for
the bushberry subgroup are established.

There are no Codex or Mexican maximum residue limits (MRLs) for residues
of clopyralid in/on the requested commodities (Appendix I).  However,
there are Canadian MRLs for residues of clopyralid at 1.0 mg/kg on
strawberry and 0.1 mg/kg on blueberry.  The Canadian MRL for strawberry
harmonizes with the existing tolerance on strawberry.  Based on the
proposed use on strawberry and bushberries, and the available residue
data, the recommended tolerances on strawberry and bushberries (subgroup
13-07B) cannot be harmonized with the Canadian MRLs.

Table 6. 	Tolerance Summary for Clopyralid.

Commodity	Proposed/Existing Tolerance (ppm)	Recommended Tolerance (ppm)
Comments; Correct Commodity Definition

40 CFR §180.431(a)

Swiss Chard	5.0	3.0	Adequate field trail data are available.

Bushberry subgroup 13-07B	6.0	0.50	Adequate field trail data are
available; however, the tolerance should be for the subgroup except
low-growing varieties.

Cranberry 	4.0	4.0	The tolerance on cranberries should remain due to
differences in use pattern and residue level versus the currently
proposed use on bushberry

Strawberry	4.0	4.0	Adequate field trial data are available to support a
7-day PHI on strawberries grown under an annual-type production system
in FL and NC only.  This tolerance will supersede the existing 1.0-ppm
tolerance already established on strawberry (grown under a perennial
production system).



References

DP Number:	193219

Subject:	ID# 062719-00073.  Review of Confined Rotational Study of
Clopyralid.

From:		G. Kramer

To:		J. Miller

Date:		8/4/93

MRID:		42815001

DP Number:	D270507

Subject:	Clopyralid.  Review of Residue Chemistry Data in Support of
Permanent or Time-Limited Tolerances Proposed for Canola (PP#1E6291),
Cherries (PP#1E6329), Crambe (PP#1E6291), Cranberry (PP#1E6340), Flax
(PP#1E6227), Garden Beets (PP#1E6333), Head and Stem Brassica
(PP#1E6999), Hops (PP#1E6283), Mustard Greens (PP#1E6334), Peaches
(PP#1E6329), Plums (PP#1E6329), Spinach (PP#1E6320), Strawberries
(PP#1E6241), Sweet Corn (PP#4F4379), Popcorn (PP#4F4379), and Turnips
(PP#1E6335).

From:		Douglas A. Dotson

To:		S. Brothers/R. Forrest

Date:		8/6/2002

MRID:		41904401, 41904402, 41904403, 44212601, 45036101, 45259901,
45372801, 45372802, 45390001, 45419801, 45436901, 45436902, 45436903,
45446901, 45447001, 45447101, 45473601, and IR-4 Rpt No. PR 07223

  SEQ CHAPTER \h \r 1 Attachments:  

Appendix I - International Residue Limit Status sheet

Appendix II - Tolerance Assessment Calculations

Appendix I.	International Residue Limit Status Sheet

INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name:  3,6-dichloro-2-pyridinecarboxylic acid	Common Name: 
Clopyralid	X Recommended tolerances

⁯ Reevaluated tolerance

⁯ Other	Date:  07/20/09

Codex Status (Maximum Residue Limits)	U. S. Tolerances

√ No Codex proposal step 6 or above

⁯No Codex proposal step 6 or above for the crops requested	Petition
Number:  PP# 8E7481

DP #s: 361787

⁯ No Limits

⁯ No Limits for the crops requested	⁯ No Limits

√  No Limits for the crops requested

Residue definition:  Clopyralid	Residue definition:  NA

Crop(s)	MRL (mg/kg)	Crop(s)	MRL (mg/kg)

Blueberry	0.1



Strawberry	1.0

















	Notes/Special Instructions: 



Appendix II.  Tolerance Assessment Calculations.

For each of the crops listed below, the Guidance for Setting Pesticide
Tolerances Based on Field Trial Data (SOP), along with the tolerance
spreadsheet, was used for calculating recommended tolerances.  As
specified in the SOP, the minimum of the 95% upper confidence limit
(UCL) on the 95th percentile and the point estimate of the 99th
percentile was selected as the tolerance value in cases when the dataset
was large (greater than 15 samples) and reasonably lognormal.  For
datasets that were small (≤15 samples) and reasonably lognormal, the
upper bound estimate of the 95th percentile based on the median residue
value was compared to the minimum of the 95% UCL on the 95th percentile
and the point estimate of the 99th percentile, and the minimum value was
selected as the tolerance value.  For datasets that were not lognormal,
the upper bound on the 89th percentile was selected as the tolerance
value (distribution-free method).  The rounding procedures specified in
the SOP were also used.

Swiss chard.  The dataset used to establish a tolerance for clopyralid
on Swiss chard consisted of field trial data representing a single
application at rates of 0.19-0.20 lb ae/A with a 28-29-day PHI.  As
specified by the SOP, the field trial application rates and PHIs are
within 25% of the maximum label application rate and minimum label PHI,
respectively.  The residue values used to calculate the tolerance are
provided in Table II-1.

All but 2 field trial sample results for Swiss chard were above the LOQ
(0.05 ppm).  The Swiss chard dataset was small (8 samples).  The dataset
was entered into the tolerance spreadsheet.  Although the result from
the approximate Shapiro-Francia test statistic (Figure I-2) indicated
that the assumption of lognormality should not be rejected, visual
inspection of the lognormal probability plot (Figure II-1) provided in
the spreadsheet indicated that the dataset was not reasonably lognormal.
 Using the tolerance spreadsheet, the recommended tolerance is 3.0 ppm
on Swiss chard.

Table II-1.	Residue data used to calculate tolerance for Clopyralid on
Swiss Chard.

Regulator:	EPA

Chemical:	Clopyralid

Crop:	Swiss Chard

PHI:	28-29 days

App. Rate:	1 application at 0.19-0.20 lb ae/A

Submitter:	IR-4

MRID Citation:	MRID 47604401

	Residues

	0.05

	0.05

	0.12

	0.21

	0.92

	0.99

	1.3

	1.9



Figure II-   SEQ Figure_II- \* ARABIC  1 .  Lognormal probability plot
of Clopyralid field trial data for Swiss chard.

Figure II- 2.   Tolerance spreadsheet summary of Clopyralid field trial
data for Swiss Chard.

Bushberry subgroup 13-07B.

The dataset used to establish a tolerance for clopyralid on the
bushberry subgroup 13-07B consisted of field trial data on blueberries
at application rates of 0.483-0.525 lb ae/A (2 applications at
0.240-0.264 lb ae/A) with a 27-33 day PHI.  As specified by the SOP, the
field trial application rates and PHIs are within 25% of the maximum
label application rate and minimum label PHI, respectively.  The residue
values used to calculate the tolerance are provided in Table II-2. 
Residues from the foliar application trial are not included in the
dataset.

The blueberry dataset is relatively large (14 samples).  The dataset was
entered into the tolerance spreadsheet.  The approximate Shapiro-Francia
test statistic (Figure II-4) indicates that the assumption of
lognormality should be rejected and visual inspection of the lognormal
probability plot for blueberry (Figure II-3) provided in the spreadsheet
supports that conclusion.  Therefore, the recommended tolerance on the
bushberry subgroup 13-07B is 0.50 ppm.

Table II-2.	Residue data used to calculate tolerance for Clopyralid on
Blueberry.

Regulator:	EPA

Chemical:	Clopyralid

Crop:	Blueberry

PHI:	27-33 Days

App. Rate:	2 applications at 0.240-0.264 lb ae/A

Submitter:	IR-4

MRID Citation:	MRID 47604402

	Residues

	0.05

	0.05

	0.05

	0.05

	0.05

	0.05

	0.056

	0.057

	0.064

	0.095

	0.16

	0.22

	0.34

	0.42



Figure II- 3.  Lognormal probability plot of Clopyralid field trial
data for Blueberry.

Figure II- 4.   Tolerance spreadsheet summary of Clopyralid field trial
data for Blueberry.

Strawberry (grown in an annual production strategy; FL and NC only)

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clopyralid on strawberry consisted of field trial data representing a
single application at rates of 0.246-0.255 lb ae/A with a 7-8 day PHI. 
As specified by the SOP, the field trial application rates and PHIs are
within 25% of the maximum label application rate and minimum label PHI,
respectively.  The residue values used to calculate the tolerance are
provided in Table II-3.

All field trial sample results for strawberry were above the LOQ (0.05
ppm).  The strawberry dataset was small (6 samples).  The dataset was
entered into the tolerance spreadsheet.  Visual inspection of the
lognormal probability plot for strawberry (FigureII-5) provided in the
spreadsheet indicated that the dataset was reasonably lognormal.  The
result from the approximate Shapiro-Francia test statistic (Figure II-6)
confirmed that the assumption of lognormality should not be rejected for
strawberry.  Using the tolerance spreadsheet, the recommended tolerance
is 4.0 ppm on strawberries.

Table II-3.	Residue data used to calculate tolerance for Clopyralid on
Strawberry.

Regulator:	EPA

Chemical:	Clopyralid

Crop:	Strawberry (annual, grown only in FL)

PHI:	7-8 Days

App. Rate:	1 application at 0.246-0.255 lb ae/A

Submitter:	IR-4

MRID Citation:	MRID 47604403

	Residues

	1.6

	2.0

	2.1

	2.7

	2.7

	3.0



Figure II- 5.  Lognormal probability plot of Clopyralid field trial
data for Strawberry.

Figure II- 6.   Tolerance spreadsheet summary of Clopyralid field trial
data for Strawberry.

Clopyralid	Summary of Analytical Chemistry and Residue Data	DP#:  361787

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