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                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
                                       
                                                                               
                                                      OFFICE OF CHEMICAL SAFETY
                                                                                              AND POLLUTION PREVENTION


MEMORANDUM


Date:	6/6/2012

Subject:	Clopyralid.  Petition for the Section 3 Registration and the Establishment of Tolerances on Apples, Brassica Leafy Greens (Subgroup 5-B), Teff, and Rapeseed (Subgroup 20-A) Except Gold of Pleasure.  Summary of Analytical Chemistry and Residue Data


PC Code:  117403 (acid)
         117401 (alkanolamine salts)
DP Barcode:  D391747
Decision No.:  450262
Registration Nos.: 62719-73, 62719-80, 62719-81, and 62719-84  
Petition:  1E7882
Regulatory Action:  Section 3 Registration
Risk Assessment Type:  NA
Case No.:  7053
TXR No.:  NA
CAS No.:  1702-17-6 (acid)
         57754-85-5 (monoethanolamine salt)
MRID No.:  48504801
40 CFR:  180.431



From:	Douglas A. Dotson, Ph.D., Chemist
	RABII                                                            
	Health Effects Division (7509P)                   

Through:	Michael Doherty, Ph.D., Senior Chemist
	RABII
	Health Effects Division (7509P)

To: 	Laura Nollen/Barbara Madden, RM Team 5
	RIMUERB
	Registration Division (7505P)
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.  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 and bushberries (Crop subgroup 13-07B)to 500 ppm in/on grass forage and hay (40 CFR §180.431(a)).  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.  Currently there are no tolerances for inadvertent or indirect residues of clopyralid.

The Interregional Research Project Number 4 (IR-4) submitted a tolerance petition proposing the use of clopyralid on apples.  As part of the same tolerance petition, IR-4 proposed to amend the Stinger[(R)] Herbicide label (EPA Reg. No. 62719-73) to expand the mustard greens use to the entire Brassica leafy greens subgroup (5-B), and to expand the use on canola, crambe, and rapeseed to the entire Rapeseed subgroup (20-A), except gold of pleasure.  In addition, IR-4 submitted a separate tolerance petition for the use of clopyralid on teff.

The only study that IR-4 submitted in support of the current petition was a combined field trial/processing study for apples.  For the other commodities, IR-4 is proposing that currently established tolerances be extended to the proposed commodities.  A tolerance of 5.0 ppm is established for mustard greens.  IR-4 is proposing that this tolerance be extended to the Brassica leafy greens subgroup.  A tolerance of 3.0 ppm is established for canola seed.  IR-4 is proposing that this tolerance be extended to rapeseed (Subgroup 20-A) except gold of pleasure.  The following tolerances are established for wheat and barley commodities:  3.0 ppm for grain, 9.0 ppm for straw, 9.0 ppm for forage (wheat only), and 9.0 ppm for hay (barley only).   IR-4 is proposing that these tolerances be extended to teff commodities.  

The end-use product that IR-4 proposed for use on these commodities is Stinger[(R)] Herbicide, which is a 3 lb acid equivalent (ae)/gal emulsifiable concentrate (EC) formulation of the monoethanolamine salt of clopyralid.

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 tolerance enforcement is parent clopyralid. 

Although teff commodities and wet apple pomace are animal feedstuffs, the maximum reasonably balanced diet (MRBD) previously determined by HED will not increase as a result of the addition of these commodities to the currently permitted uses for clopyralid.  Clopyralid is already registered for use on cereal grain commodities, grass forage and hay (both with tolerances of 500 ppm), as well as other more esoteric feedstuffs (such as sugar beet molasses at 10 ppm).  As a result, issues pertaining to residues in livestock commodities do not need to be addressed in 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 apple field trials, residues of clopyralid in apple fruit, juice, and wet pomace 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.  The lowest level of method validation (LLMV) was 0.05 ppm for apple fruit, juice, and wet pomace.  
The submitted apple field trial data are adequate and support the proposed use.  IR-4 performed an adequate number of trials and they were performed in the recommended EPA growing zones.  The application rate was 1x the maximum proposed rate, and the samples were collected at 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 an LOQ tolerance of 0.05 ppm for apple fruit.  For the other commodities in this tolerance petition, the tolerances are being translated from other commodities with established tolerances.

In the apple processing study, no detectable residues were found in the samples of apple fruit, apple juice, or wet apple pomace.  Because of phytotoxicity concerns, IR-4 did not perform an exaggerated rate study.  No residues were found in the processed commodities; which indicates that if concentration did occur, it was not to a considerable extent.

The existing confined rotational crop study adequately supports the rotational crop restrictions specified on the current label.

MRL Harmonization

There are no Codex or Mexican maximum residue limits (MRLs) for residues of clopyralid in/on the proposed commodities (Attachment I).  However, there is a Canadian MRL for residues of clopyralid in or on flax at 0.2 ppm.  This MRL does not harmonize with the existing U.S. tolerance of 3.0 ppm for flax seed (or the proposed tolerance of 3.0 ppm for the rapeseed subgroup).  Based on the differing use patterns and the available residue data, the recommended tolerance for the flaxseed subgroup cannot be harmonized with the Canadian MRL on flax.


Regulatory Recommendations and Residue Chemistry Deficiencies

There are no residue chemistry data deficiencies that would preclude granting the requested registrations and establishing tolerances for residues of clopyralid on the proposed commodities.  The proposed tolerances, the recommended tolerances, and the correct commodity definitions are given in Table 7.


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.  

IR-4 submitted a tolerance petition proposing the use of clopyralid on apples.  As part of the same tolerance petition, IR-4 proposed to amend the Stinger[(R)] Herbicide label (EPA Reg. No. 62719-73) to expand the mustard greens use to the entire Brassica leafy greens subgroup (5-B), and to expand the use on canola, crambe, and rapeseed to the entire Rapeseed subgroup (20-A), except gold of pleasure.  In addition, IR-4 submitted a separate tolerance petition for the use of clopyralid on teff.

The only study that IR-4 submitted in support of the petition was a combined field trial/processing study for apples.  For the other commodities, IR-4 is proposing that currently established tolerances be extended to the proposed commodities.  A tolerance of 5.0 ppm is established for mustard greens.  IR-4 is proposing that this tolerance be extended to the Brassica leafy greens subgroup.  A tolerance of 3.0 ppm is established for canola seed.  IR-4 is proposing that this tolerance be extended to rapeseed (Subgroup 20-A) except gold of pleasure.  The following tolerances are established for wheat and barley commodities:  3.0 ppm for grain, 9.0 ppm for straw, 9.0 ppm for forage (wheat only), and 9.0 ppm for hay (barley only).   IR-4 is proposing that these tolerances be extended to teff commodities.  

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.  

Table 1.   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 products (EUP)
Stinger[(R)] Herbicide (EPA Reg. No. 62719-73)
Lontrel[(R)] 35A Herbicidal Concentrate (EPA Reg. No. 62719-84)


Table 2.   Physicochemical Properties of the Technical Grade Clopyralid 
Parameter
Value
References
Physical State
Solid
A world Compendium, The Pesticide Manual, 14[th]  Edition. C.D. S Tomlin (Editor), 2006.
Color
Colorless

Melting Point/Range
151-152°C

Dissociation Constant (pKa)
2

Density at 20°C
1.57 g/cm3 

Vapor Pressure at 25°C
1.0 x 10[-5] mm Hg (1.33 mPa)

Water Solubility at 20°C
7.85 g/L

Solvent solubility (g/L) at 20°C
Acetone:  250
Ethyl acetate:  102
Xylene:  4.6
Hexane:  6.0

Octanol/water partition coefficient, Log (KOW)
-1.81 (pH 5) 
-2.63 (pH 7) 
-2.55 (pH 9)



860.1200  Directions for Use

Stinger[(R)] Herbicide is currently registered to Dow AgroSciences for use on a wide variety of crops for the postemergence control of weeds.  The label includes use directions for the following crops:  (1) mustard greens, (2) canola (rapeseed) and crambe, and (3) barley, oats, and wheat.  IR-4 submitted supplemental labels for the Brassica leafy greens subgroup and the rapeseed subgroup.  The use directions on those supplemental labels are consistent with the use directions for the commodities from which the tolerances are being extended.  IR-4 also submitted a supplemental label for apples.  The use directions for teff are the same as those on the Stinger[(R)] label for barley, oats, and wheat.  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
                                       
                      Use Directions and Limitations [2]
                                     Apple
Apply to non-bearing (well-established, 1 year or older) and bearing trees.  Apply to actively growing weeds.  Apply with ground equipment only.
                     Stinger, 3.0 lb ae/gal EC [62719-73]
                                  0.094-0.25
                                       1
                                     0.25
                                      30
                                     days
Apply in a minimum of 10 gal/A.  Do not use in Florida or in Nassau or Suffolk Counties, New York.  Do not apply by aircraft.
                    Leafy Brassica Greens Subgroup, 5-B[3]
Apply to actively growing weeds.  Apply with ground equipment only.
                     Stinger, 3.0 lb ae/gal EC [62719-73]
                                   0.06-0.25
                                       2
                                      0.5
                                      30
                                     days
Apply in a minimum of 10 gal/A, with a minimum RTI of 14 days.  Do not apply by aircraft.


                Rapeseed Subgroup 20-A, Except Gold of Pleasure
Apply in the 2- to 6-leaf stage of crop growth.  Apply to actively growing weeds.  Apply with ground and aerial equipment only.
                     Stinger, 3.0 lb ae/gal EC [62719-73]
                                  0.113-0.25
                                       1
                                     0.25
                                       7
                                     days
Use in the State of Oregon only.  Apply in a minimum of 20 gal/A.  Do not use with a surfactant.  Apply with ground and aerial equipment only.
               Teff (Use Directions for Barley, Oats, and Wheat)
Apply when crop is from 3-leaf stage up to early boot stage of growth.
                     Stinger, 3.0 lb ae/gal EC [62719-73]
                                  0.094-0.125
                                       1
                                     0.125
                                Not Speci-fied
Do not harvest hay from treated grain fields[4].
[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.
[3]	For use and distribution only in the states of AZ, AR, CA, CO, DE, FL, GA, MD, MI, MO, NJ, NM, NY, NC, OH, OK, PA, SC, TX, VA and WI.  Not for sale or distribution in Nassau and Suffolk Counties in New York State.
[4]	Do not permit lactating dairy animals or meat animals being finished for slaughter to forage or graze treated grain fields within one week after treatment.


Conclusions.  The supplemental label for apples is adequate to allow evaluation of the residue data relative to the proposed use.  The available field trial data support the proposed use directions.  The supplemental labels for Brassica leafy greens and rapeseed as well as the SLN label for teff are adequate.  The use directions and restrictions are adequate to ensure that over-tolerance residues will not result in any plant or animal commodities.  

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 [14]C-residue was determined to be only parent compound.  Although data are available for only two dissimilar crops (leafy vegetables and cereal grains), 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

Goat and poultry metabolism studies were previously reviewed.  The nature of the residue in livestock commodities is understood.  The only major residue is parent clopyralid.  Although teff commodities and wet apple pomace are animal feedstuffs, the maximum reasonably balanced diet (MRBD) previously determined by HED will not increase as a result of the addition of these commodities to the currently permitted uses for clopyralid.  Clopyralid is already registered for use on cereal grain commodities, grass forage and hay (both with tolerances of 500 ppm), as well as other more esoteric feedstuffs (such as sugar beet molasses at 10 ppm).  As a result, issues pertaining to residues in livestock commodities do not need to be addressed in the current petition.

860.1340 Residue Analytical Methods

Enforcement method.  The Pesticide Analytical Manual (PAM) Vol. II lists a GC/ECD method for determining 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 Method.  In the submitted field trials, residues of clopyralid in/on samples of apples and apple processed commodities were determined using a slightly modified version of the current tolerance enforcement method.  The method that was used was the Cornell Analytical Laboratory Method titled: "Residue Analysis of 3, 6-Dichloropicolinic Acid (Clopyralid) Residues by GC/Electron Capture Detector, Version #19."  Ten grams of sample are extracted with 0.5% NaOH.  A portion is then extracted with ether and methylated with freshly prepared diazomethane.  After evaporation of the ether, the residue is re-dissolved in toluene and cleaned up on an activated alumina A column and eluted with toluene.  The sample is then analyzed for clopyralid methyl ester by GC/ECD.

The residue analytical method for clopyralid residues in/on apple and apple processing samples was adequately validated in conjunction with field sample analyses and is acceptable as a data-gathering method.  The calculated limits of quantitation (LOQ) were 0.05 ppm for apple fruit, 0.04 ppm for apple juice, and 0.07 ppm for apple pomace.  The lowest level of method validation (LLMV) was 0.05 ppm in/on all three matrices (fruit, juice, and pomace).  The calculated limits of detection (LOD) were 0.02 ppm for apple fruit, 0.01 ppm for apple juice, and 0.02 ppm for apple pomace.

Conclusions.  An adequate GC/ECD method (Method ACR 75.6) is available for enforcing the proposed tolerances on apples, Brassica leafy vegetables, rapeseed, and teff.  The data collection method used for analysis of apples and processed apple commodities is also adequate.

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.  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 of 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 
                                    Matrix 
                               (RAC or Extract)
                                    Analyte
                             Storage Temperature 
                                      (C)
                                  Recoveries
                                      (%)
                            Actual Storage Duration
                                    (days)
               Interval of Demonstrated Storage Stability (days)
                                  Apple Fruit
                                  Clopyralid
                                  -21 +- 7 C
                                    108-120
                                    76-279
                                      267
                                  Apple Juice
                                  Clopyralid
                                  -21 +- 7 C
                                    106-108
                                      104
                                      175
                                 Apple Pomace
                                  Clopyralid
                                  -21 +- 7 C
                                   92 - 96*
                                      113
                                      179
*After subtracting apparent residues of 0.058 ppm observed in the untreated control apple pomace sample

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

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

Although teff commodities and wet apple pomace are animal feedstuffs, the maximum reasonably balanced diet (MRBD) previously determined by HED will not increase as a result of the addition of these commodities to the currently permitted uses for clopyralid.  Clopyralid is already registered for use on cereal grain commodities, grass forage and hay (both with tolerances of 500 ppm), as well as other more esoteric feedstuffs (such as sugar beet molasses at 10 ppm).  As a result, issues pertaining to residues in livestock commodities are not being addressed in the current petition.

860.1500 Crop Field Trials

The only study that IR-4 submitted in support of the current tolerance petition was a combined field trial/processing study for apples.  For the other commodities, IR-4 is proposing that currently established tolerances be extended to the proposed commodities.  As a result, no new field trial data were submitted for the Brassica leafy greens subgroup, the rapeseed subgroup, or for teff.   

48504801.der (Apples)

As stated above, IR-4 submitted a field trial study to support the proposed uses of clopyralid (3 lb ae/gal EC) on apples.  Apples have two associated regulated processed commodities, apple juice and wet apple pomace.  The study that IR-4 submitted was a combined field trial/processing study.  The results of the field trial study are discussed below, and the residue data are summarized in Table 5.
   
Table 5.  Summary of Residue Data from Crop Field Trials with Clopyralid
                                  Crop Matrix
                                       
                             Total Applic. Rate[1]
                                   (lb ae/A)
                                      PHI
                                    (days) 
                             Residue Levels (ppm)



                                       n
                                     Mean
                                   Std. Dev.
                                    HAFT[2]
                                      Min
                                      Max
                                  Apple Fruit
                                 0.244 - 0.275
                                     28-30
                                      24
                                   <0.05
                                     NA[3]
                                   < 0.05
                                   < 0.05
                                   < 0.05
                                       
[1] One foliar application of Stinger Herbicide at approximately 0.25 lb ae/A was made
[2] HAFT = Highest Average Field Trial.
[3]NA = Not applicable


Apples.  IR-4 conducted twelve field trials in the 2007 and 2008 growing seasons.  Three trials were conducted in New York (EPA Growing Region 1), one in North Carolina (Region 2), two in Michigan (Region 5), one in Colorado (Region 9), one in California (Region 10) and four in Washington State (Region 11).  The total number of field trials was in accordance with OPPTS Guideline 860.1500. 

At each trial, treatment was via a single broadcast application to the orchard floor at the approximate rate of 0.25 lb acid equivalent per acre (ae/A).  Spray adjuvants were not used in any of the field trials.  Samples were harvested 28 to 30 days after the application and placed into frozen storage shortly after harvest.  At the NY27 trial, an additional apple sample was taken from each plot for processing into apple juice and apple pomace.

The maximum storage duration was 279 days for field-treated fresh apple samples.  This duration is supported by appropriate storage stability data.
 
In all 24 samples of apple fruit, residues were below the LOQ of 0.05 ppm.  Although no quantifiable residues were found in the samples of apple fruit, the registrant did not perform an exaggerated rate study. 

Conclusions.  The magnitude of the residue study of clopyralid on apple is acceptable.  The number and location of the field trials satisfy OPPTS Guideline 860.1500.  The residue data are adequate to support the establishment of a tolerance of 0.05 ppm for apple fruit.

860.1520 Processed Food and Feed

Apples

At one of the apple field trial sites (the NY27 trial), an apple sample was taken from each plot for processing into apple juice and apple pomace.  The trial was performed at a 1x application rate (0.246 lb ae/A) and samples were taken at a PHI of 30 days.  Because of phytotoxicity concerns, IR-4 did not perform an exaggerated rate study.  
  
The samples were processed at the processing facility on the day of harvest.  A grab sample was taken from each of the processing apple samples prior to processing into juice and wet pomace.  The processed and grab samples were stored frozen until being shipped.  A typical commercial process was used for processing.  Small lots of fresh apples (1-2 bushels) were ground in a Hammer-mill.  Wet mash was collected in a container and loaded into one or more cloth stacks (cheeses) on the hydraulic press.  When the stack was complete (up to 5 cloths depending on sample size), the hydraulic pump was activated and the sample was pressed to 2200-3000 psi for a minimum of 5 minutes to achieve efficient juice yield.  The juice was collected in (1/2) to 1 gallon plastic bottles for storage.  After the pressing cycle, the cloths were opened up and the wet pomace cake was broken up to obtain the wet pomace sample.

The maximum storage duration was 279 days for field-treated fresh apple samples, 104 days for apple juice, and 113 days for pomace.  These durations are supported by appropriate storage stability data.

Clopyralid residues were below the LOQ of 0.05 ppm in the apple fruit samples (both treated and untreated).  No quantifiable residues were found in apple juice.  A residue of 0.056 ppm was found in the treated apple pomace sample; however, the corresponding untreated control sample had an apparent residue of 0.042 ppm.  After subtraction of the residue detected in the control from the residue in the treated pomace sample, the resulting residue would be 0.014 ppm, which is considerably below the reported LOQ.
  
Table 6.   Residue Data from Apple Processing Study with Fluazinam
Location
(City, State; Year)
                                  Total Rate
                                   (lb ae/A)
                                     PHI 
                                    (days)
                                   Commodity
                              Fluazinam Residues
                                     (ppm)
                                       
                          Fluazinam Processing Factor
North Rose, NY; 1993
                                     0.246
                                      30
                                  Fruit (RAC)
                              <0.05, <0.05
                                      NA

                                       
                                       
                                     Juice
                                   <0.05
                                      NA

                                       
                                       
                                  Wet Pomace
                                  <0.05[1]
                                      NA
[1]After subtracting apparent residue (0.042 ppm) detected in the untreated control sample from the residue in the wet pomace sample (0.056), the residue level was < 0.05 ppm.


Conclusions.  The apple processing study is acceptable.  It can be concluded that if concentration occurred in juice and pomace, it was to a very limited extent.

860.1650 Submittal of Analytical Reference Standards

An analytical reference standard for clopyralid monoethanolamine salt is currently available in the EPA National Pesticide Standards Repository.  The expiration date is 2-26-2015 (electronic communication, Theresa Cole, ACB, 2/27/2012).
 
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 [[14]C]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 any time:  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.

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

The submitted apple field trial and processing studies are adequate to support the proposed tolerance of 0.05 ppm for apple, fruit.  The trials were performed at a 1x application rate and samples were taken at the proposed PHI.  Geographic representation of the field trials was adequate.  Separate tolerances are not needed for apple juice or wet apple pomace.  HED uses the OECD tolerance calculator to determine recommended tolerances.  However, in cases where all field trial samples are below the LOQ of the analytical method, HED recommends that the tolerance be set at the LOQ.  As a result, the recommended tolerance for apple is 0.05 ppm.

For the other commodities in this tolerance petition, IR-4 is proposing that currently-established tolerances be extended to the proposed commodities.  A tolerance of 5.0 ppm is established for mustard greens.  IR-4 is proposing that this tolerance be extended to the Brassica leafy greens subgroup.  A tolerance of 3.0 ppm is established for canola seed.  IR-4 is proposing that this tolerance be extended to rapeseed (Subgroup 20-A) except gold of pleasure.  The following tolerances are established for wheat and barley commodities:  3.0 ppm for grain, 9.0 ppm for straw, 9.0 ppm for forage (wheat only), and 9.0 ppm for hay (barley only).   IR-4 is proposing that these tolerances be extended to teff commodities.  There are no residue chemistry issues that would preclude the extension of these tolerances.  
There are no Codex or Mexican maximum residue limits (MRLs) for residues of clopyralid in/on the proposed commodities (Attachment I).  However, there is a Canadian MRL for residues of clopyralid in or on flax at 0.2 ppm.  This MRL does not harmonize with the existing U.S. tolerance of 3.0 ppm for flax seed (or the proposed tolerance of 3.0 ppm for the rapeseed subgroup).  Based on the differing use patterns and the available residue data, the recommended tolerance for the flaxseed subgroup cannot be harmonized with the Canadian MRL on flax.

Table 7 provides a summary of the recommended tolerances for the proposed commodities.


Table 7.  Tolerance Summary for Clopyralid
                                       
                      Commodity as Proposed by Registrant
                           Proposed Tolerance (ppm)
                         Recom-mended Tolerance (ppm)

Comments
(correct commodity definition)
                              40 CFR §180.431(a)
Apple
                                     0.05
                                     0.05
Adequate field trial data are available.
Leafy Brassica greens subgroup 5B
                                      5.0
                                      5.0
The proposed and recommended tolerance is based on the existing tolerance for mustard greens, the representative commodity of the Leafy Brassica greens subgroup
(Brassica, leafy greens, subgroup 5B)
Rapeseed subgroup 20A, except Gold of pleasure, seed
                                      3.0
                                      3.0
The proposed and recommended tolerance is based on the existing tolerance of 3.0 ppm for rapeseed, canola, and flax seed
(Rapeseed, subgroup 20A, except gold of pleasure)
Rapeseed subgroup 20A, except Gold of pleasure, meal
                                      6.0
                                      6.0
The proposed and recommended tolerance is based on the existing tolerance of 6.0 ppm for canola meal and flax meal
(Rapeseed, meal)
Rapeseed subgroup 20A, except Gold of pleasure, forage
                                      3.0
                                     None
Tolerance is not needed because rapeseed forage is not a significant livestock feed item.
Teff, forage
                                      9.0
                                      9.0
Based on wheat forage (9.0 ppm)
Teff, grain
                                      3.0
                                      3.0
Based on wheat and barley grain (3.0 ppm)
Teff, hay
                                      9.0
                                      9.0
Based on barley hay (9.0 ppm)
Teff, straw
                                      9.0
                                      9.0
Based on wheat and barley straw (9.0 ppm)




References

MRID No. 48504801.  J. Corley, (2010).  Clopyralid: Magnitude of the Residue on Apple. Project Number: 03623.  Unpublished study prepared by The Center for Minor Crop Pest Management Technology Center of New Jersey Rutgers, The State University of New Jersey

D361787, M. Doherty, Clopyralid  -  Petition for Tolerances on Swiss chard, Bushberry Subgroup 13-07B, and Strawberry (Regional Restriction).  Summary of Analytical Chemistry and Residue Data, 10/27/2009

D361316, M. Doherty, et al., Clopyralid  -  Human Health Risk Assessment to Evaluate New Uses on Swiss Chard, Bushberry Subgroup (13-07B), and Strawberry (Regional Restriction), 12/3/2009

D270507, D. Dotson, Clopyralid.  Review of Residue Chemistry Data in Support of Permanent or Time-Limited Tolerances Proposed for Canola...Summary of Analytical Chemistry and Residue Data, 8/6/2002

D193219, G. Kramer, ID# 062719-00073. Review of confined rotational study of clopyralid, MRID# 428150-01, 8/4/93



Attachment I.  International Residue Limit Status Sheet


                        Clopyralid (117403; 2-22-2012)
                                       
Summary of US and International Tolerances and Maximum Residue Limits 
Residue Definition:  
US
Canada
Mexico[2]
Codex[3]
40 CFR 180.431:

Plants/Livestock:  clopyralid, 3,6-dichloro-2-pyridinecarboxylic acid
3,6-dichloro-2-pyridinecarboxylic acid

None
Commodity[1]
Tolerance (ppm) /Maximum Residue Limit (mg/kg)

                                      US
Canada
Mexico[2]
Codex[3]
Apple
                                     0.05



Leafy brassica greens, subgroup 5-B
                                      5.0



Teff, grain
                                      3.0



Teff, hay
                                      9.0



Teff, forage
                                      9.0



Teff, straw
                                      9.0



Rapeseed, subgroup 20-A, except gold of pleasure, seed
                                      3.0
                                       
                                   0.2 flax
                                       


Rapeseed, subgroup 20-A, except gold of pleasure, meal
                                      6.0



Rapeseed, subgroup 20-A, except gold of pleasure, forage
                                      3.0













Completed:  M. Negussie; 02/24/2012
[1] Includes only commodities of interest for this action.  Tolerance values should be the HED recommendations and not those proposed by the applicant.
2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains.  PoP = processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC. 

