Document ID: EPA-HQ-OPP-2012-0706-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2013-11-27T05:00Z

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

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

MEMORANDUM

Date:	12-JUL-2013  

Subject:	Metaldehyde.  Section 3 Registration for Proposed Uses on Grass Grown for Seed, Leaf Petioles [Crop Subgroup 4B], Wetland Taro, Field & Sweet Corn, Mint, and Soybeans, and for Amendments to Existing Tolerances [Crop Subgroups 13-07A, B, & G].  Summary of Analytical Chemistry and Residue Data.

PC Code:  053001
DP Barcode:  D408745, D311876
Decision No.:  468286
Registration No.:  NA
Petition No.:  2E8070
Regulatory Action: Section 3 Registration
Risk Assessment Type: NA
Case No.: NA
TXR No.:  NA
CAS No.: 108-62-3
MRID Nos.: 488982-01 thru -06; and 476230-04
40 CFR:  §180.523

FROM:		William H. Donovan, Ph.D., Chemist
		Risk Assessment Branch (RAB) V
		Health Effects Division (7509P)

THROUGH:	Ideliz Negrón-Encarnación, Ph.D., Chemist
			Michael S. Metzger, Branch Chief
			RAB V/VII
			Health Effects Division (7509P)
	
TO:		Laura Nollen/Barbara Madden, RM 05
			Risk Integration, Minor Use, Emergency Response Branch
			Registration Division (7505P)

		And

		Jill Bloom, Chemical Review Manager 
		Risk Management and Implementation Branch II (RMIB2)
		Pesticide Re-Evaluation Division (PRD) (7508P)
		 

1.0	Executive Summary

The Interregional Research Project Number 4 (IR-4) has submitted a petition for establishing a tolerance for metaldehyde in or on grass grown for seed, leaf petioles (crop subgroup 4B), wetland taro, field and sweet corn, mint, and soybean; and for replacing the existing tolerances for Berry group 13 and strawberry with corresponding tolerances for crop subgroups 13-07A, B, and G.  For soybean, a regional registration was requested while national registrations are intended for all other requested crops.     

Adequate residue chemistry data have been provided to support the new use requests for metaldehyde.  The nature of the residue in plants is adequately understood for the purposes of this petition based on previously submitted metabolism studies on lettuce and sugar beet.  Livestock metabolism and feeding studies have been waived.  Field trials are of adequate number and geographic representation.  Crop field trial data analyses employed validated and sufficiently sensitive analytical methods that determine the residue of concern, and are supported by adequate storage stability data.  Appropriate studies were submitted for mint to determine the extent of residue concentration of metaldehyde in mint oil.  Although processing studies are typically required for corn and soybean, these studies were not needed for metaldehyde as exaggerated rate studies conducted as part of the magnitude of the residue studies showed no residues above the limit of quantitation (LOQ) in the RACs at exaggerated rates of 5X (corn) or 10X (soybean).  A field rotational crop study indicates that a plant back interval (PBI) of 30 days is appropriate for all rotated crops not listed on the label.  Use of the OECD MRL calculation procedures resulted in recommended tolerance levels that differ from the levels proposed, which were based on use of the NAFTA calculator.  

2.0	Regulatory Recommendations

The residue chemistry database is adequate for the new use requests for metaldehyde, and there are no residue chemistry considerations that would preclude establishment of the recommended tolerances. 

2.1	Data Deficiencies/Data Needs

There are no residue chemistry deficiencies identified for this petition.  

2.2	Tolerance Considerations

2.2.1	Enforcement Analytical Method

EN-CAS(TM) Method No. ENC-3/99, Revision 1 (a gas chromatography/mass spectrometry (GC/MS) method) is acceptable for tolerance enforcement of metaldehyde residues in plants.  For this method, residues in homogenized plant matrices (except citrus and mint oil) are extracted with dichloromethane (DCM) containing sodium sulfate, filtered, concentrated, and analyzed by GC/MS using the m/z 89 and 45 ions for quantitation and confirmation, respectively.  For citrus and mint oil, the residue extraction step is slightly modified; thus, residues in citrus oil are dissolved in methanol (MeOH), diluted with hexane and partitioned with water.  Residues in the resulting MeOH:water fraction are then partitioned into DCM, concentrated, and analyzed by GC/MS.  Mint oil samples are diluted with hexane and partitioned with 5% acetic acid and then DCM, prior to GC/MS analysis.  For wheat grain, rape seed, and other oily matrices an additional cleanup step consisting of a hexane/methanol partition is also used.  The limit of quantitation (LOQ) for metaldehyde in/on plant commodities is 0.05 ppm.

Since this method was used for data collection and adequate validation data were reported, an adequate enforcement method is available to enforce tolerances for the proposed new uses of metaldehyde.

2.2.2	Recommended Tolerances

HED has examined the residue chemistry database for metaldehyde.  Pending submission of revised Sections B (see Directions for use) and F (see requirements under Proposed Tolerances) there are no residue chemistry issues that would preclude the establishment of tolerances for residues of metaldehyde in/on the requested crops and crop subgroups.  The tolerance expression for metaldehyde [40 CFR §180.523(a)] should be changed to read as follows:

      Tolerances are established for residues of the molluscicide metaldehyde, including its metabolites and degradates, in or on the commodities listed below.  Compliance with the tolerance levels specified below is to be determined by measuring only metaldehyde, 2,4,6,8-tetramethyl-1,3,5,7-tetroxocane, in or on the commodity.

Table 2.2.2a 	Tolerance Summary for Metaldehyde, §180.523(a).
Commodity
                           Proposed Tolerance (ppm)
                          Recommended Tolerance (ppm)
Comments; Correct Commodity Definition
Leaf petioles subgroup 4B
                                     0.80
                                     0.50

Peppermint, tops
                                      3.5
                                      4.0

Spearmint, tops
                                      3.5
                                      4.0

Peppermint, oil
                                      14
                                      12

Spearmint, oil
                                      14
                                      12

Caneberry subgroup 13-07A
                                     0.15
                                     0.15

Bushberry subgroup 13-07B
                                     0.15
                                     0.15

Berry, low growing, subgroup 13-07G
                                     6.25
                                     6.25

Taro, corm
                                     0.25
                                     0.15

Taro, leaves
                                     0.60
                                      1.0

Corn, field, grain
                                     0.05
                                     0.05

Corn, sweet, kernel plus cob with husks removed
                                     0.05
                                     0.05

Grass, forage
                                      1.5
                                      2.0

Grass, hay
                                      1.8
                                      2.0

Corn, field, forage
                                     0.25
                                     0.30

Corn, field, stover
                                     0.15
                                     0.10

                      Tolerances that need to be proposed
Corn, sweet, forage
                                     None
                                     0.30

Corn, sweet, stover
                                     None
                                     0.10

Further, 40 CFR §180.523(c) should read as follows:  

      "Tolerances with a regional registration as defined in 180.1(l) are established for residues of the molluscicide metaldehyde, including its metabolites and degradates, in or on the commodities listed below.  Compliance with the tolerance level specified below is to be determined by measuring only metaldehyde, 2,4,6,8-tetramethyl-1,3,5,7-tetroxocane, in or on the commodity.
      
Table 2.2.2c 	Tolerance Summary for Metaldehyde, §180.523(c).
Commodity
                           Proposed Tolerance (ppm)
                          Recommended Tolerance (ppm)
Comments; Correct Commodity Definition
Soybean, seed
                                     0.05
                                     0.05

Note to RD:  Upon establishment of the recommended tolerances listed in Table 2.2.2, the established tolerances for "Berry group 13" and "Strawberry" should be revoked as they will be included in the new tolerances for crop subgroups 13-07A, B, and G.

2.2.3	Revisions to Petitioned-For Tolerances

For some commodities, the recommended tolerances are different than the proposed tolerance levels.  Most of the recommended tolerance levels were based on use of the Organization for Economic Cooperation and Development (OECD) tolerance calculation procedures, while most of the proposed tolerance levels appear to be based on the North America Free Trade Agreement (NAFTA) tolerance calculation procedures.  Sweet corn forage and stover tolerances should be proposed to support the use of metaldehyde in/on sweet corn.  Differences between the proposed and recommended tolerances for mint oil likely arise from the use of maximum residues and processing factors instead of following HED policy of using highest average residues and average processing factors.

2.2.4	International Harmonization

As there are no CODEX or Canadian MRLs established for metaldehyde, no international harmonization issues are expected to arise from establishment of the recommended tolerances (see Appendix B).

2.3	Label Recommendations

The proposed labels should contain the following restriction:

A 30-day plant back interval (PBI) is appropriate for all rotational crops.  Labeled crops may be replanted immediately.  

All other metaldehyde labels should be amended in registration review to contain the aforementioned restriction.

3.0	Introduction

3.1	Chemical Identity

TABLE 3.1.	Nomenclature of Metaldehyde.
Compound
Chemical Structure

Common name
Metaldehyde
Company experimental names
Not applicable
IUPAC name
r-2,c-4,c-6,c-8-tetramethyl-1,3,5,7-tetroxocane  (or)
2,4,6,8-tetramethyl-1,3,5,7-tetraoxacyclo-octane
CAS name
2,4,6,8-tetramethyl-1,3,5,7-tetroxocane
CAS #
108-62-3 (tetramer) and 9002-91-9 (homopolymer)
End-use products/EP
7.5% G (Durham Metaldehyde Granules; EPA Reg No. 5481-103); 
4% P/T (Deadline MPs Mini-Pellets; EPA Reg. No. 5481-511); and 
4% RTU/L (Deadline Force II; EPA Reg. No. 8119-6)

3.2	Physical/Chemical Characteristics

Physiochemical properties for metaldehyde are shown in Table 3.2. 

TABLE 3.2.	Physicochemical Properties of Metaldehyde.
Parameter
Value
Reference
Melting point/range
246°C
Metaldehyde RED, PC Chapter
pH
Not applicable due to the low solubility of metaldehyde in water.
                                       -
Density
1.27 g/cm[3]
                          Metaldehyde RED, PC Chapter
Water solubility (20°C)
0.222 g/L at 20°C

Solvent solubility (g/L at 20.3-22.4°C)
5.21 x 10[-2]  in hexane
0.53            in toluene
1.56            in tetrahydrofuran
1.73            in methanol

Vapor pressure
1 mm Hg at 20°C
6.6 +- 0.3 Pa at 25°C

Dissociation constant (pKa)
3.5 Pa (m[3]/mol) (Henry's Law Constant)

Octanol/water partition coefficient, Log (Kow)
1.33 (log POW = 0.12) at 20°C

3.3	Pesticide Use Pattern/Directions for Use (860.1200)

Table 3.3.  Summary of Directions for Use of Metaldehyde Granular Formulation
                     Application Timing, Type, and  Equip.
                          Formulation [EPA Reg. No.]
                          Application Rate (lb ai/A)
                        Max. No. Application per Season
                   Max. Seasonal Application Rate (lb ai/A)
                                  PHI (days)
                        Use Directions and Limitations
                             Grass Grown for Seed
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      1.6
                                       4
                                      6.4
                                      21
                                 RTI = 14 days
                          Leaf petioles (Subgroup 4B)
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      1.0
                                       4
                                       4
                                       1
                                 RTI = 21 days
                        Mint (Peppermint and Spearmint)
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      1.0
                                       4
                                       4
                                       1
                                 RTI = 21 days
                                Taro (wetland)
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      1.0
                                      15
                                     15.0
                                       7
                                 RTI = 21 days
Caneberry (Subgroup 13-07A), Bushberry (Subgroup 13-07B), Low growing berry (Subgroup 13-07G)
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      0.8
                                       3
                                      2.4
                                       0
                                 RTI = 14 days
                             Sweet and Field Corn
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      1.0
                                       4
                                       4
                                      N/A
 PHI = N/A because applications must be completed no later than flag stage.  
                                 RTI = 7 days
                                   Soybean*
                  Broadcast (ground & handheld equipment)
                                   71096-13
                                      0.4
                                       3
                                      1.2
                                      N/A
PHI = N/A because applications must be completed prior to pod formation.  Treated soybeans may not be fed to livestock, and livestock may not graze in the treated fields.
                                 RTI = 7 days
   * For use in the following states:  Alabama, Arkansas, Connecticut, Delaware, Georgia, Louisiana, Maine, Maryland, Massachusetts, Mississippi, North Carolina, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, and Virginia.

The use directions are adequate to allow evaluation of the residue data relative to the proposed uses.  The proposed maximum application rates, RTIs, and PHIs are supported by the submitted field trial data.  Refer to section 2.3 for recommended modifications to the proposed labels.
 
4.0	Metabolite/Degradate Residue Profile

4.1	Nature of the Residue

4.1.1 	Summary of Plant Metabolism (860.1300)

Residue Chemistry Chapter of the RED; DP No. D311889, 05-MAY-2005, F. Fort

The qualitative nature of metaldehyde residues in plants is understood based on the adequate lettuce and sugar beet metabolism studies (DP Barcode D224844, S. Hummel, 7/02/96).  The HED Metabolism Committee concluded that the regulated residue of concern in plants is parent metaldehyde, per se.

In the lettuce metabolism study, radioactive residues were taken up and translocated to leaves following a single directed application of [[14]C]metaldehyde to the soil at a rate equivalent to 13.8 lb ai/A (10x).  The maximum total radioactive residues (TRR) were 4.43 ppm and 3.78 ppm in the inner and outer lettuce leaves, respectively, with a PHI of 28 days.  Up to 95.3% of TRR was identified as the parent metaldehyde.

In the sugar beet metabolism study, a single directed application of [[14]C]metaldehyde was made to the soil at a rate equivalent to 13.8 lb ai/A (10x).  The TRR were 1.65-5.60 ppm in/on sugar beet foliage and 0.30-1.13 ppm in/on sugar beet root (PHI = 48days), indicating uptake and translocation to foliage.  Metaldehyde was the only radioactive residue identified in the organic fractions of foliage (~33% TRR, 1.84 ppm) and root (~35% TRR, 0.39 ppm).  Although no analytical analyses of the nonextractable residues of foliage (43.2% TRR, 2.42 ppm) and root (43.4% TRR, 0.49 ppm) were conducted, overall the plant metabolism data for metaldehyde support the HED Metabolism Committee's decision to regulate only the parent in the tolerance expression for plant commodities.

4.1.2	Summary of Livestock Metabolism (860.1300)

Residue Chemistry Chapter of the RED; DP No. D311889, 05-MAY-2005, F. Fort

Based upon the rapid degradation of metaldehyde to acetaldehyde in mammalian systems and the subsequent incorporation of acetaldehyde into the tricarboxylic acid cycle, the Agency has concluded that the transfer of metaldehyde residues in livestock commodities is unlikely.  Therefore, the requirements for livestock metabolism and feeding studies have been waived (Greybeard Committee: Metaldehyde, 3/11/97).  

4.1.3	Summary of Confined Rotational Crops (860.1850)

D298113, T. Jimerson, 15-FEB-2005

On December 9, 2004, the Chemistry Science Advisory Council (ChemSAC) granted a waiver for OPPTS Guideline 860.1850, Confined Accumulation in Rotational Crops for the chemical metaldehyde, provided that a field accumulation in rotational crop study is conducted.  The rationale was that because of its chemical structure (a tetramer of acetaldehyde), the primary metabolite would be acetaldehyde, a chemical whose metabolism in plants and animals is well documented.  Also, because it is likely that total radioactive residues (TRR) greater than 0.01 ppm would be found in a confined rotational crop study, a field accumulation in rotational crop study is requested.  

4.2	Residues of Concern Summary and Rationale

The qualitative nature of metaldehyde residues in plants is understood based on lettuce and sugar beet metabolism studies.  The HED Metabolism Committee (7/2/96) concluded that the regulated residue of concern in plants is parent metaldehyde.  This conclusion was confirmed in the Metaldehyde Reregistration Eligibility Decision (RED) document (D327385, M. Lloyd et. al., April 3, 2006).

Table 4.2.   Summary of Metabolites and Degradates to be included in the Risk Assessment and Tolerance Expression
Matrix
Residues included in Risk Assessment
Residues included in Tolerance Expression
Plants
Primary Crop
Metaldehyde
Metaldehyde

Rotational Crop
Metaldehyde
Metaldehyde
Livestock
Not Applicable
Not Applicable
Drinking Water
Metaldehyde
Not Applicable

5.0	Residue Profile

5.1	Residue Analytical Methods (860.1340) 

5.1.1	Data Collection Methods

IR-4 made use of the existing metaldehyde enforcement method for data collection purposes.  The method, entitled "Analytical Residue Method for the Determination of Metaldehyde in Crops by GC/MS" (EN-CAS(TM) Method No. ENC-3/99, Revision 1), has been used for the determination of metaldehyde in a wide variety of crop matrices.  The method description, method validation data, and an independent laboratory (ILV) validation of the method were reviewed in support of the metaldehyde RED.

For this method, residues in homogenized plant matrices (except oils) are extracted with dichloromethane (DCM) containing sodium sulfate, filtered, concentrated, and analyzed by GC/MS using the m/z 89 and 45 ions for quantitation and confirmation, respectively.  For citrus oil, residues are dissolved in methanol (MeOH), diluted with hexane and partitioned with water.  Residues in the resulting MeOH:water fraction are then partitioned into DCM, concentrated, and analyzed by GC/MS.  For wheat grain, rape seed, and other oily matrices an additional cleanup step consisting of a hexane/methanol partition is also used.  The level of quantitation (LOQ) for metaldehyde in/on plant commodities is 0.05 ppm, and LOD was not reported.

Method validation data for the GC/MS method demonstrated adequate method recoveries from plant commodities (lettuce, tomato, cabbage lemon, strawberry, orange, broccoli, grapefruit, mustard greens, wheat grain, rape seed, orange oil, and orange dry pulp) fortified with metaldehyde at 0.05-1.0 ppm.  Recoveries were all within the acceptable 70-120% range and averaged 81-107%, with relatively low standard deviations (+- 3.4 to 14%, n=6-8).  In addition, the method has undergone a successful ILV trial using samples of lettuce, grapefruit, and rape seed fortified at 0.05 and 0.50 ppm.

5.1.2	Multi-Residue Methods (860.1360)

D315914, J. Deluzio, 13-APR-2005

There are no analytical methods listed in PAM, Vol. II for the analysis of metaldehyde.   The FDA multiresidue methods are not suitable for analysis of metaldehyde.  The GC/FID response for metaldehyde in Level I testing (Module DG6, 130C) gave an inadequate response as the relative retention time for metaldehyde was <0.3, and Level II testing could not be performed.  In addition, solvent front and matrix interferences precluded quantitation of metaldehyde through Protocol D.  

5.1.3	Tolerance Enforcement Methods

EN-CAS(TM) Method No. ENC-3/99, Revision 1 is acceptable for tolerance enforcement of metaldehyde residues in plants.  For this method, residues in homogenized plant matrices (except citrus and mint oil) are extracted with dichloromethane (DCM) containing sodium sulfate, filtered, concentrated, and analyzed by GC/MS using the m/z 89 and 45 ions for quantitation and confirmation, respectively.  For citrus and mint oil, the residue extraction step is slightly modified; thus, residues in citrus oil are dissolved in methanol (MeOH), diluted with hexane and partitioned with water.  Residues in the resulting MeOH:water fraction are then partitioned into DCM, concentrated, and analyzed by GC/MS.  Mint oil samples are diluted with hexane and partitioned with 5% acetic acid and then DCM, prior to GC/MS analysis.  For wheat grain, rape seed, and other oily matrices an additional cleanup step consisting of a hexane/methanol partition is also used.  The level of quantitation (LOQ) for metaldehyde in/on plant commodities is 0.05 ppm.

Since this method was used for data collection and adequate validation data were reported, an adequate enforcement method is available to enforce tolerances for the proposed new uses of metaldehyde.

5.1.4	Submittal of Analytical Reference Standards (860.1650)

The analytical standard for metaldehyde (CAS # 108-62-3) at the EPA National Pesticide Standards Repository expired on February 1, 2013 [personal communication from T. Cole of ACB/BEAD to W. Donovan, 05/21/2013].  A fresh reference standard should be provided to the Repository, and then replenished as requested by the Repository.  The reference standard should be sent to the Analytical Chemistry Lab, which is located at Fort Meade, to the attention of Theresa Cole at the following address:

	USEPA
	National Pesticide Standards Repository/Analytical Chemistry Branch/OPP
	701 Mapes Road
	Fort George G. Meade, MD  20755-5350

The full 9 digit zip code is mandatory or the mail will be returned.

5.2	Storage Stability (860.1380)

As detailed in the residue chemistry chapter of the metaldehyde RED, acceptable storage stability studies for metaldehyde have been reported.  Thus, metaldehyde is stable in frozen storage for at least 8 months in citrus oil, 12 months in lettuce, strawberry, broccoli, and oranges, and 23 months in tomatoes.    

In support of the crop field trial data submitted for the proposed new uses of metaldehyde, concurrent storage stability studies were conducted for grass, celery, corn, mint, soybean, and taro.  These studies confirm and extend the previous findings of residue stability, with recoveries in the acceptable range of 70-120% for the intervals needed to cover the sample storage intervals from the field trial studies, see Table 5.2.2.  

TABLE 5.2.2.	Summary of Storage Conditions in Primary Crop, Processing Studies, and Rotational Crops.

Crop

Matrix
                           Storage Temperature (°C)
                        Maximum Storage Duration (days)
               Interval of Demonstrated Storage Stability (days)
                    Primary Crops and Processed Commodities
Celery
Stalk

                                     <= 0

140
321
Corn
Forage

223
556

K + CWHR

194
555

Grain

197
193

Stover

190
293
Grass
Forage

176
483

Hay

180
482
Mint
Leaf

61
318

Oil

701
737
Soybean 
Seed

263
237
Taro
Leaf

267
377

Corm

387
380
                               Rotational Crops
Radish
Roots, tops

                                       
                                      -17
420
450
Sorghum
Forage, grain, stover

260
450
Wheat
Forage, hay, grain, straw

310
450

5.3	Residue Data

5.3.1	Crop Field Trials (860.1500)
48898201.der (Grass Field Trials)
48898202.der (Celery Field Trials)
48898203.de1 (Mint Field Trials)
48898204.der (Taro Field Trials)
48898205.der (Field & Sweet Corn Field Trials)
48898206.der (Soybean Field Trials)

The crop field trial data submitted in support of this petition were generated by IR-4.  Because corn and soybean are not minor crops and because of some unique circumstances detailed below, IR-4 consulted the HED Chemistry Science Advisory Council (ChemSAC) for guidance on these trials.  

For corn, IR-4 considers the proposed metaldehyde use to be a minor use on a major crop because slugs and snails are a potential pest problem on up to 8% of the national corn acreage (mostly in Zone 2), and in a typical year only a small fraction of that would be infested and require treatment.  Thus, IR-4 conducted 15 trials in 2006 and 2007, expecting no residues, based on a use pattern which specified a 1-day PHI, 4 x 1.0 lb ai/A, and a 21-day RTI.  As residues were found in these trials, IR-4 revised the use pattern to require the last application prior to flag stage (which equates to a PHI of approximately 60 days or more for grain).  The ChemSAC concurred with IR-4's proposal to conduct 5 additional trials at an exaggerated rate of 5X according to the revised use pattern, analyzing only grain, while basing tolerances for corn feedstuffs on data from the 15 trials conducted in 2006/2007 (ChemSAC minutes, 4/2/2008).

For soybean, IR-4 considers the proposed metaldehyde use to be a minor use on a major crop because this molluscicide is needed only in no-till soybean after periods of rain, and the need is greatest in the Northeastern U.S., the Mid-Atlantic States, and Ohio.  Due to the limited geographical scope of the infestation, IR-4 chose to develop data to support a regional registration for metaldehyde on soybean.  The ChemSAC concurred with IR-4's proposal to conduct 7 trials at a 1X rate plus one trial at an exaggerated rate of 10X to support a regional registration in the requested states (ChemSAC minutes, 3/31/2010).

None of the trials used adjuvants and no residue decline studies were conducted in any of the trials.  

Grass Field Trials

A total of 13 field trials on grasses were conducted in the United States during the 2005 and 2006 growing seasons in North American Free Trade Agreement (NAFTA) Growing Zones 7 (ND, 4 trials; NE, 2 trials), 11 (ID, 2 trials; WA, 1 trial), and 12 (OR, 4 trials).  The crop field trials were conducted using wheatgrass (2 trials), bluegrass (4 trials), fescue (3 trials), rye grass (1 trial), orchard grass (1 trial), bluestem grass (1 trial), and bromegrass (1 trial).

Each trial consisted of one untreated control plot and one treated plot.  At each trial location, the treated plots received four broadcast applications to the soil of a 4% pelleted (P/T) bait of metaldehyde during vegetative through jointing stages of development at rates of 1.6 lb a.i./A/application, for a total seasonal rate of 6.4 lb a.i./A.  Retreatment intervals (RTIs) were 9-15 days.  Applications were made using shaker cans or granular spreaders.  Grass forage was harvested at preharvest intervals (PHIs) of 7-22 days.  Grass hay was harvested at PHIs of 14-30 days and was allowed to dry for 1-10 days prior to collection.  

Residues of metaldehyde were found in all grass forage samples and in grass hay in 11 out of 13 trials.  A summary of the field trial results is shown in Table 5.3.1.1, below.

TABLE 5.3.1.1.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  

Commodity
                                       
                            Total Rate lb a.i./A 
                                       
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Grass forage
                                       
                                   6.40-6.43
                                       
                                     7-22
                                      13
                                     0.072
                                     1.42
                                     0.082
                                     1.19
                                     0.508
                                     0.534
                                     0.308
Grass hay
                                       
                                   6.40-6.43
                                       
                                     14-30
                                      13
                                   <0.05
                                     1.29
                                   <0.05
                                     1.12
                                     0.490
                                   <0.520
                                     0.393
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  For calculation of median, mean, and standard deviation, the LLMV (0.05 ppm) was used for any results reported as <LLMV.
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

The number of grass field trials and their geographical distribution are adequate.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The forage and hay data sets were analyzed using the OECD tolerance calculation procedures to determine the recommended tolerance level of 2.0 ppm for both matrices (see Appendix C). 

Celery Field Trials

A total of 8 field trials on celery were conducted in the United States during the 2006 and 2007 growing seasons in NAFTA Growing Zones 3 (FL, 2 trials), 5A (MI, 1 trial), and 10 (CA, 5 trials).  

Each trial consisted of one untreated (control) plot and one treated plot.  At each trial location, the treated plots received four applications of a 4% pelleted (P/T) bait of metaldehyde to the soil in the furrow between, or within, the crop beds during vegetative stages of development at a rate of 1.0 lb a.i./A/application, for a total seasonal rate of 4.0 lb a.i./A.  RTIs were 20-23 days.  Applications were made using various types of containers with a single aperture that were shaken in the furrow, or by using a gloved hand.  The pellets were applied to the furrows that separated the beds at all trials with the exception of the trials in FL, where pellets were applied to a furrow in the middle of each bed next to the drip tape.  Celery (untrimmed stalks and leaves) was harvested with a PHI of 1 day.  

Residues of metaldehyde were above the method LOQ in 3 of the 8 celery trials.   A summary of the field trial results is shown in Table 5.3.1.2, below.

TABLE 5.3.1.2.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  
Commodity
                            Total Rate lb a.i./A 
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Celery stalks and leaves
                                       
                                     4.00
                                       
                                       1
                                       8
                                   <0.05
                                     0.334
                                   <0.05
                                     0.240
                                     0.119
                                     0.129
                                     0.089
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  For calculation of median, mean, and standard deviation, the LLMV (0.05 ppm) was used for any results reported as <LLMV.
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

The number of celery field trials and their geographical distribution are adequate.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The celery data were analyzed using the OECD tolerance calculation procedures to determine the recommended tolerance level of 0.50 ppm (see Appendix C). 

Mint Field Trials

A total of 5 field trials on mint were conducted in the United States during the 2006 growing season in NAFTA Growing Zones 5A (WI, 2 trials, both on peppermint) and 11 (ID, 1 trial, on peppermint; WA, 2 trials, one on peppermint and one on spearmint).

Each trial consisted of one untreated control plot and one treated plot.  At each trial location, the treated plots received four broadcast applications to the ground of a 4% pelleted (P/T) bait formulation of metaldehyde  during vegetative stages of development at rates of 1.0 lb a.i./A/application, for a total seasonal rate of 4.0 lb ai/A.  RTIs were 19-22 days.  Applications were made using a hand-held crank spreader or a container with a single aperture that was shaken in the furrow.  Mint was harvested with a PHI of 1 day.  

Residues of metaldehyde were found in all 5 mint trials.  A summary of the field trial results is shown in Table 5.3.1.3, below.

TABLE 5.3.1.3.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  
Commodity
                            Total Rate lb a.i./A 
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Mint tops (leaves and stems)
                                   4.00-4.08
                                       
                                       1
                                       5
                                     0.626
                                     2.78
                                     0.672
                                     2.39
                                     0.917
                                     1.15
                                     0.701
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

The number of mint field trials and their geographical distribution are adequate.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The mint data were analyzed using the OECD tolerance calculation procedures to determine the recommended tolerance level of 4.0 ppm (see Appendix C). 

Taro Field Trials

A total of 3 crop field trials on taro were conducted in the United States during the 2006 growing season in NAFTA Growing Zone 13 (HI) under wetland conditions.  

Each trial consisted of one untreated (control) plot and one treated plot.  At each trial location, the treated plots received 15 applications of a 4% pelleted (P/T) bait of metaldehyde broadcast over the crop during vegetative stages of development at a rate of 1.0 lb a.i./A/application, for a total seasonal rate of 15.0 lb a.i./A.  RTIs were 19-23 days.  Applications were made using a hand-cranked granular spreader.  Taro leaves and corms were sampled from separate plants at PHIs of 6-7 days.  

Residues of metaldehyde were found in two of the three taro leaf samples and in one of the three taro corm samples.  A summary of the field trial results is shown in Table 5.3.1.4, below.

TABLE 5.3.1.4.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  
Commodity
                            Total Rate lb a.i./A 
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Taro Leaves
                                       
                                     15.0
                                       
                                      6-7
                                       3
                                   <0.05
                                     0.451
                                   <0.05
                                     0.404
                                   <0.057
                                   <0.170
                                     0.203
Taro Corms
                                       
                                     15.0
                                       
                                      6-7
                                       3
                                   <0.05
                                     0.105
                                   <0.05
                                     0.085
                                   <0.05
                                   <0.062
                                     0.020
   1 Except for sample min/max, values reflect per trial averages; n = no. of field trials.  For calculation of median, mean, and standard deviation, the LLMV (0.05 ppm) was used for any results reported as <LLMV.
   2 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of taro field trials and their geographical distribution are adequate.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The taro data were analyzed using the OECD tolerance calculation procedures to determine the recommended tolerance levels of 1.0 ppm for taro leaf and 0.15 ppm for taro corm (see Appendix C). 

Field and Sweet Corn Field Trials

A total of 20 crop field trials on field corn were conducted in the United States during the 2006, 2007, and 2008 growing seasons in NAFTA Growing Zones 1 (NY, 2 trials), 2 (MD, 4 trials; NJ, 1 trial), 5 (ND, 3 trials; OH and SD, 1 trial each), 5A (MI, 4 trials; WI, 3 trials), and 7 (ND, 1 trial).  
Each trial consisted of one untreated (control) plot and one treated plot.  Fifteen trials were conducted during the 2006 and 2007 growing seasons.  At these trials, the treated plots received four or five applications of a 4% pelleted (P/T) bait of metaldehyde generally beginning at the silking, fruiting, or vegetative stages of development at rates of 1.0 lb a.i./A/application, for total seasonal rates of 4.0-5.0 lb a.i./A.  The target RTI was 21 days.  Applications were broadcast to the ground, except at the two MI trials where applications were directed to the furrows on the outside of the bed of two rows of corn that comprised the treated plot.  The highest total rate of application was at the OH trial, which was the only site to receive five applications.  The fifth application became necessary because the crop was not mature after four applications.  Applications were made using either a shaker container or a drop spreader.  Samples of forage and kernels + cob with husks removed (K+CWHR) were sampled at the appropriate crop growth stage (milk), regardless of the number of applications that had been made and the PHI.  The number of applications that had been applied to these samples was 1 or 2, and the PHIs were 1-20 days.  Samples of grain and stover were harvested at maturity, 1 day after the final (fourth or fifth) application (PHI = 1 day); after cutting, stover was allowed to dry prior to collection.  

Five trials were conducted during the 2008 growing season.  In four of these trials, the treated plots received two applications of prior to the initiation of the flag stage of development at rates of 5.0 lb a.i./A/application, for total seasonal rates of 10.0 lb ai/A.  Applications were made as a broadcast to the ground, and RTIs were 7-14 days.  In the fifth of these trials in 2008, due to a misunderstanding, the treated plot in MD received two applications beginning prior to the initiation of the flag stage of development at a rate of 1.0 lb a.i./A/application, for a total seasonal rate of 2.0 lb a.i./A.  Applications were broadcast to the ground, and the RTI was 21 days, with the final application occurring after the flag stage.  In these five trials, grain was harvested when it was commercially mature, with a PHI of 57-97 days; no other field corn commodities were collected and analyzed.  

Metaldehyde residues exceeded the method LOQ in 5 of the 15 trials for corn forage and stover.  One field corn grain sample had residues above the LOQ.  None of the simulated sweet corn K+CWHR samples had residues above the LOQ.  In the 2008 exaggerated rate trials, no field corn grain samples had residues above the LOQ.  A summary of the field trial results is shown in Table 5.3.1.5, below.
TABLE 5.1.3.5.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  

Commodity
                            Total Rate lb a.i./A 
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Field Corn Forage
                                 1.00-2.00[3]
                                       
                                    1-20[4]
                                      15
                                   <0.05
                                   0.365[5]
                                   <0.05
                                 <0.208[5]
                                   <0.05
                                   <0.067
                                     0.041
Sweet Corn K+CWHR
                                       
                                       
                                      15
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                      N/A
Field Corn Grain
                                 3.99-5.00[6]
                                       
                                       1
                                      15
                                   <0.05
                                     0.061
                                   <0.05
                                   <0.055
                                   <0.05
                                   <0.05
                                      N/A
Field Corn Stover
                                       
                                       1
                                      15
                                   <0.05
                                     0.111
                                   <0.05
                                     0.081
                                   <0.05
                                   <0.056
                                     0.010
Field Corn Grain
                                    2.00[7]
                                       
                                      57
                                       1
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                      N/A
Field Corn Grain
                                10.00-10.02[7]
                                       
                                     74-97
                                       4
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                      N/A
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  For calculation of median, mean, and standard deviation, the LLMV (0.05 ppm) was used for any results reported as <LLMV.  N/A = Not Applicable.
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.
[3]  Either 1 or 2 applications.
[4]  The mean +- Std. Dev. of the PHIs was 9.5 +- 12.8 days.
5   The sample maximum and HAFT were from the same crop field trial, which had a PHI of 9 days.
[6]  For 14 crop field trials, there were 4 applications with a total rate of 3.99-4.32 lb a.i./A, and for one crop field trial (0.06-OH17) there were 5 applications with a total rate of 5.00 lb a.i./A.  The one trial with the higher rate had residues of <0.05, <0.05 [<0.05] ppm in/on grain and residues of (0.0270), (0.0245) [<0.05] in/on stover.
[7]  Two applications.

The field trial program for field and sweet corn is consistent with the 4/2/2008 ChemSAC decision.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The corn data were analyzed using the OECD tolerance calculation procedures to determine the recommended tolerance levels of 0.30 ppm for field corn forage and 0.10 ppm for field corn stover (see Appendix C).  These levels are also recommended for sweet corn forage and stover.  LOQ tolerance levels of 0.05 ppm are recommended for field corn grain and sweet corn kernel plus cob with husks removed.  

Soybean Field Trials

A total of 7 field trials on soybean were conducted in the United States during the 2008 growing season in NAFTA Growing Zones 1 (NY; 1 trial), 2 (MD; 2 trials, TN; 1 trial), 4 (TN; 2 trials) and 5 (OH; 1 trial).  

Each trial consisted of one untreated (control) plot and one treated plot.  At each trial location, the treated plots received three applications of a 4% pelleted (P/T) bait of metaldehyde broadcast to the soil during the vegetative through blooming stages of development at rates of 0.40 lb a.i./A/application, for total seasonal rates of 1.2 lb a.i./A.  RTIs were 7-16 days.  At one trial location (MD13), one additional treated plot received three applications of a 4% P/T bait of metaldehyde broadcast to the soil during the vegetative through early blooming stage of development at a 10x rate of 4.0 lb a.i./A/application, for a total seasonal rate of 12.0 lb a.i./A; RTIs were 14-15 days.  Applications were made using shaker bottles.  At PHIs of 69-105 days, soybean seeds were collected by using a combine, by cutting plants and running them through a thrasher, or by collecting pods and shelling them.  

No residues above the LOQ of 0.05 ppm were found in any soybean seed sample including the one sample treated at a 10x rate.  No residue data on soybean forage or hay were analyzed, consistent with the label restriction not allowing livestock grazing or feeding.  A summary of the field trial results is shown in Table 5.3.1.6, below.
 
TABLE 5.3.1.6.	Summary of Residue Data from Crop Field Trials with Metaldehyde.  
Commodity
                            Total Rate lb a.i./A 
                                  PHI (days)
                               Residue Levels[1]
                                     (ppm)

                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                   Std. Dev.
Soybean Seed
                                     1.20
                                       
                                    69-105
                                       7
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                    N/A[3]
Soybean Seed
                                     12.0
                                       
                                      69
                                       1
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                      N/A
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  For calculation of median, mean, and standard deviation, the LLMV (0.05 ppm) was used for any results reported as <LLMV in Table C.3.
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.
[3]  N/A = Not Applicable.

The field trial program for soybean is consistent with the 3/31/2010 ChemSAC decision regarding this regional registration.  The samples were analyzed using a suitable method and the sample storage intervals are supported by storage stability data.  The data support a tolerance level of 0.05 ppm for soybean seed.  

Considerations Regarding Crop Subgroups 13-07A, B, & G
D292383, J. Deluzio, 8/1/2005

Tolerances have been established for metaldehyde on Berry group 13 at 0.15 ppm and on strawberry at 6.25 ppm (see 40 CFR 180.523).   The representative commodities for Berry group 13 were raspberry or blackberry, and blueberry.  The tolerance for Berry group 13 was based on data from the representative berry commodities.  The berry crop group was expanded since a Federal Register notice dated December 7, 2007.  Raspberry or blackberry is now the representative commodity for Caneberry subgroup 13-07A.   Data previously submitted on raspberry or blackberry support a new tolerance for subgroup 13-07A at 0.15 ppm (45816402.der).  Blueberry is the representative commodity for Bushberry subgroup 13-07B.   Data previously submitted on blueberry support a new tolerance for subgroup 13-07A at 0.15 ppm (45816401.der).  Strawberry is the representative commodity for Berry, low growing, subgroup 13-07G.   Data previously submitted on strawberry support a new tolerance for subgroup 13-07G at 6.25 ppm (46010509.der).

5.3.2	Field Rotational Crops (860.1900)
47623004.der

Lonza, Inc. submitted a limited field rotational crop study with metaldehyde on radish, germ sorghum, and winter wheat.  Two field trials were conducted in the Unites States, encompassing Regions 5 (1 trial in Michigan) and Region 10 (1 trial in California) during the 2005-2006 growing season.  At each test site, three applications of metaldehyde were made to bare ground at a nominal target application rate of 1.0 lb ai/A/application and a 14-day RTI, for a total of 3.0 lb ai/A/season.  Radish plants were planted at nominal plant back intervals (PBI) of 30, 120 and 365 days.  Sorghum plants were planted at nominal PBIs of 30 and 365 days, while wheat plants were planted at a nominal 120-day PBI.  Plants were harvested at maturity and analyzed using the analytical method EN-CAS(TM) No. ENC-3/99, Revision 1.  The following plant matrices were analyzed for residues of metaldehyde:  radish  -  tops and roots; sorghum  -  forage, grain, and stover; and wheat  -  forage, grain, hay, and straw.  Leafy vegetables were not included in the study because of the availability of magnitude of the residue field trial data in/on broccoli, cabbage, mustard greens, and leaf lettuce reflecting primary crop uses.

Conclusions:  The maximum frozen storage interval for any sample was 14 months.  Concurrent storage stability data demonstrated stability in all matrices tested for at least 15 months.  Residues of metaldehyde were not detected above the LOQ (0.05 ppm) in any of the samples analyzed at any PBI.  Based on use of the appropriate application rate, adequate crop diversity in the tested crops, and the results showing that metaldehyde residues are not taken up by rotational crops, HED concludes that 30-day PBIs are appropriate for all rotational crops.  This rotational crop PBI specification should be included on all metaldehyde labels concerning agricultural crop uses.  Labeled crops may be replanted immediately.  

5.3.3	Processed Food and Feed (860.1520)
48898203.de2 (Mint Processing Study)

Metaldehyde processing studies were conducted on mint in two trials (WI and WA).  At each test site, four broadcast applications of metaldehyde were made to bare ground at a nominal target application rate of 1.0 lb ai/A/application and a 21-day RTI, for a total of 4.0 lb ai/A/season. Following a 1-day PHI, mint samples were harvested and processed into oil.  

Detectable levels of metaldehyde were found in mint RACs and mint oil, allowing determination of processing factors (see Table 5.3.3).  From these studies an average processing factor of 5.1x was determined for mint oil.    
 
Table 5.3.3.	Residue Data from Apple, Orange, and Plum Processing Studies with Metaldehyde.

RAC
                                  Crop Matrix
                                  Total Rate
                                   (lb ai/A)
                                     PHI 
                                    (days)
                                       n
                                Residues (ppm) 
                             Processing Factor[1]
                            Avg. Processing Factor
Mint
                                     Tops
                                      4.0
                                       1
                                       2
                                 0.672, 0.917
                                      --
                                      --

                                      Oil
                                       
                                       
                                       
                                  2.97, 5.26
                                  4.42, 5.74
                                     5.08
[1]  The processing factor was calculated by dividing the residue in the processed sample by the residues in the unprocessed RAC sample.  

The mint processing study was adequate to determine an average processing factor of 5.1x for mint oil.  The recommended tolerance level for mint oil was determined as the product of the mint HAFT and the average processing factor.  Thus, 2.39 ppm x 5.1 = 12 ppm.  No separate processing studies were needed for corn or soybean, since exaggerated rate studies at 5x and 10x, respectively, showed no detectable metaldehyde residues in the RACs.  
  

5.3.4	Meat, Milk, Poultry and Eggs (860.1480)

Not applicable as the Agency approved a waiver for livestock feeding studies.

5.4	Food Residue Profile

Adequate residue chemistry data have been provided for metaldehyde.  Field trials are of adequate number and geographic representation.  Data analyses employed validated analytical methods and are supported by appropriate storage stability data.  Sufficient studies were submitted for mint to elucidate the fate of metaldehyde in processed commodities derived from these crops:  metaldehyde residues were found to concentrate in mint oil, with an average processing factor of 5.1x.  Multiplying the mint highest average field trial (HAFT) value [2.39 ppm] by the average processing factor resulted in the recommended tolerance level of 12 ppm for mint oil.  The Agency waived livestock metabolism and feeding studies; thus, all uses of metaldehyde are classified under 40 CFR §180.6 (a) (3), no reasonable expectation of finite residues with respect to residues in livestock commodities.  Limited rotational crop field trials demonstrate that residues are not expected in crops planted 30-days after metaldehyde is applied to soil; therefore, 30-day plant back intervals (PBIs) are appropriate for all crops in rotation to primary crops. 

6.0	Tolerance Derivation

The recommended tolerances for metaldehyde were derived by 1) use of the OECD MRL calculation procedures for crops with measurable residue levels, 2) use of the LOQ for crops where residues in the field trials were not measurable, 3) direct translation where appropriate, and 4) use of the standard tolerance equation for processed commodities, HAFT x Average Processing Factor = processed commodity tolerance. 

List of Appendices
   A. Number of Crop Field Trials and Geographical Distributions.
   B. International Residue Limits Table.
   C. Tolerance Calculations.

Attachments
48898201.der.docx
48898202.der.docx
48898203.de1.docx
48898203.de2.docx
48898204.der.docx
48898205.der.docx
48898206.der.docx 
47623004.der.docx
Appendix A

TABLE A.1.1.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                                    Grasses

                                   Submitted
                                 Requested[1]

                                       
                                    Canada
                                     U.S.
1
                                      --
                                      --
                                      --
1A
                                      --
                                      --
                                      --
2
                                      --
                                      --
                                      --
3
                                      --
                                      --
                                      --
4
                                      --
                                      --
                                      --
5
                                      --
                                      --
                                      --
5A
                                      --
                                      --
                                      --
5B
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
7
                                       6
                                      --
                                      --
7A
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
10
                                      --
                                      --
                                      --
11
                                       3
                                      --
                                      --
12
                                       4
                                      --
                                      --
13
                                      --
                                      --
                                      --
14
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
Total
                                      13
                                       
                                     12/9
[1] As per OCSPP 860.1500, Tables 2 and 5 for grasses; the trials are to be conducted in all areas across the country.   The second number reflects a 25% reduction in the number of trials allowed for the crop as a representative commodity in support of a crop group/subgroup tolerance or when application results in no quantifiable residues.  For a full number of trials, Table 2 specifies 4 trials for each of the three grass cultivars (Bermuda grass, bluegrass, and bromegrass or fescue).

TABLE A.1.2.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                                    Celery

                                   Submitted
                                 Requested[1]

                                       
                                    Canada
                                     U.S.
1
                                      --
                                      --
                                      --
1A
                                      --
                                      --
                                      --
2
                                      --
                                      --
                                      --
3
                                       2
                                      --
                                      2/1
4
                                      --
                                      --
                                      --
5
                                      --
                                      --
                                      1/1
5A
                                       1
                                      --
                                      --
5B
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
7
                                      --
                                      --
                                      --
7A
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
10
                                       5
                                      --
                                      5/4
11
                                      --
                                      --
                                      --
12
                                      --
                                      --
                                      --
13
                                      --
                                      --
                                      --
14
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
Total
                                       8
                                       
                                    8/6[2]
[1] As per OCSPP 860.1500, Table 5 for celery.  The second number reflects a 25% reduction in the number of trials allowed for the crop as a representative commodity in support of a crop group/subgroup tolerance or when application results in no quantifiable residues.

TABLE A.1.3.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                        Mint (Peppermint and Spearmint)

                                   Submitted
                                 Requested[1]

                                       
                                    Canada
                                     U.S.
1
                                      --
                                      --
                                      --
1A
                                      --
                                      --
                                      --
2
                                      --
                                      --
                                      --
3
                                      --
                                      --
                                      --
4
                                      --
                                      --
                                      --
5
                                      --
                                      --
                                       2
5A
                                     2[2]
                                      --
                                      --
5B
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
7
                                      --
                                      --
                                      --
7A
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
10
                                      --
                                      --
                                      --
11
                                     3[3]
                                      --
                                       3
12
                                      --
                                      --
                                      --
13
                                      --
                                      --
                                      --
14
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
Total
                                       5
                                       
                                       5
[1] As per OCSPP 860.1500, Tables 1 and 5 for mint.  A tolerance for mint may be obtained using residue data for spearmint and/or peppermint.
[2] Both trials were on peppermint.
[3] Two trials were on peppermint and one was on spearmint.

TABLE A.1.4.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                                     Taro

                                   Submitted
                                 Requested[1]

                                       
                                    Canada
                                     U.S.
1
                                      --
                                      --
                                      --
1A
                                      --
                                      --
                                      --
2
                                      --
                                      --
                                      --
3
                                      --
                                      --
                                      --
4
                                      --
                                      --
                                      --
5
                                      --
                                      --
                                      --
5A
                                      --
                                      --
                                      --
5B
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
7
                                      --
                                      --
                                      --
7A
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
10
                                      --
                                      --
                                      --
11
                                      --
                                      --
                                      --
12
                                      --
                                      --
                                      --
13
                                       3
                                      --
                                      --
14
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
Total
                                      13
                                       
                                       
[1] As per OCSPP 860.1500, Table 1, a minimum of four treated samples from four independently treated plots is required for each trial -- two samples reflecting the maximum proposed application rate (1x) and two reflecting a 2x rate.  No requested distribution per NAFTA Zones is provided. 

TABLE A.1.5.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                                 Corn (Field)

                                   Submitted
                                 Requested[1]

      Trials with 4 or 5 applications before harvesting grain and stover
Trials with 2 applications prior to flag stage unless noted, with residues analyzed only in grain
                                    Canada
                                     U.S.
1
                                       1
                                       1
                                      --
                                      1/1
1A
                                      --
                                      --
                                      --
                                      --
2
                                       4
                                     1[2]
                                      --
                                      1/1
3
                                      --
                                      --
                                      --
                                      --
4
                                      --
                                      --
                                      --
                                      --
5
                                       4
                                       1
                                      --
                                     17/12
5A
                                       5
                                       2
                                      --
                                      --
5B
                                      --
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
                                      1/1
7
                                       1
                                      --
                                      --
                                      --
7A
                                      --
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
                                      --
10
                                      --
                                      --
                                      --
                                      --
11
                                      --
                                      --
                                      --
                                      --
12
                                      --
                                      --
                                      --
                                      --
13
                                      --
                                      --
                                      --
                                      --
14
                                      --
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
                                      --
Total
                                      15
                                       5
                                       
                                     20/15
[1] As per OCSPP 860.1500, Table 5 for corn (field).  The second number reflects a 25% reduction in the number of trials allowed for the crop as a representative commodity in support of a crop group/subgroup tolerance or when application results in no quantifiable residues.
[2]  The second application was administered after the flag stage.

TABLE A.1.6.	Trial Numbers and Geographical Locations.
NAFTA Growing Regions
                                    Soybean

                                   Submitted
                                 Requested[1]

                                       
                                    Canada
                                     U.S.
1
                                       1
                                      --
                                      --
1A
                                      --
                                      --
                                      --
2
                                       3
                                      --
                                      2/2
3
                                      --
                                      --
                                      --
4
                                       2
                                      --
                                      3/2
5
                                       1
                                      --
                                     15/11
5A
                                      --
                                      --
                                      --
5B
                                      --
                                      --
                                      --
6
                                      --
                                      --
                                      --
7
                                      --
                                      --
                                      --
7A
                                      --
                                      --
                                      --
8
                                      --
                                      --
                                      --
9
                                      --
                                      --
                                      --
10
                                      --
                                      --
                                      --
11
                                      --
                                      --
                                      --
12
                                      --
                                      --
                                      --
13
                                      --
                                      --
                                      --
14
                                      --
                                      --
                                      --
15
                                      --
                                      --
                                      --
16
                                      --
                                      --
                                      --
17
                                      --
                                      --
                                      --
18
                                      --
                                      --
                                      --
19
                                      --
                                      --
                                      --
20
                                      --
                                      --
                                      --
21
                                      --
                                      --
                                      --
Total
                                       7
                                       
                                     20/15
[1] As per OCSPP 860.1500, Table 5 for soybean (dried).  The second number reflects a 25% reduction in the number of trials allowed for the crop as a representative commodity in support of a crop group/subgroup tolerance or when application results in no quantifiable residues.

Appendix B.  International Residue Limits Table

Table B1.  Summary of US and International Tolerances and Maximum Residue Limits for Metaldehyde (053001)
Residue Definition:
US
Canada
Mexico[2]
Codex
40 CFR 180.523:
Plant: Metaldehyde
None

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

US
Canada
Mexico[2]
Codex
Leaf petioles subgroup 4B
0.50

Peppermint, tops
4.0

Spearmint, tops
4.0

Peppermint, oil
12

Spearmint, oil
12

Caneberry subgroup 13-07A
0.15

Bushberry subgroup 13-07B
0.15

Berry, low growing, subgroup 13-07G
6.25

Taro, corm
0.15

Taro, leaves
1.0

Corn, field, grain
0.05

Corn, sweet, kernel plus cob with husks removed
0.05

Soybean, seed
0.05

Grass, forage
2.0

Grass, hay
2.0

Corn, field, forage
0.30

Corn, field, stover
0.10

Completed:  M. Negussie; 05/15/2013
[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.

Appendix C. Results of OECD Tolerance Calculations

                                  Metaldehyde
                                 Grass forage
                                      USA
                            6.4 lb ai/A, 21-day PHI
 
 
Total number of data (n)
                                      13
Percentage of censored data
                                      0%
Number of non-censored data
                                      13
Lowest residue
                                     0.082
Highest residue
                                     1.190
Median residue
                                     0.510
Mean
                                     0.536
Standard deviation (SD)
                                     0.308
Correction factor for censoring (CF)
                                     1.000
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     1.190
- Mean + 4 SD
                                     1.769
- CF x 3 Mean
                                     1.609
Unrounded MRL
                                     1.769
 
                                       
Rounded MRL
                                       2
 
                                       
 
 

                               Residues (mg/kg)
                                       n
                                     0.082
                                       1
                                     0.16
                                       1
                                      0.3
                                       1
                                     0.35
                                       1
                                     0.39
                                       1
                                     0.47
                                       1
                                     0.51
                                       1
                                     0.53
                                       1
                                     0.59
                                       1
                                     0.67
                                       1
                                     0.79
                                       1
                                     0.94
                                       1
                                     1.19
                                       1

                                  Metaldehyde
                                   Grass hay
                                      USA
                            6.4 lb ai/A, 21-day PHI
 
 
Total number of data (n)
                                      13
Percentage of censored data
                                      15%
Number of non-censored data
                                      11
Lowest residue
                                     0.050
Highest residue
                                     1.120
Median residue
                                     0.490
Mean
                                     0.521
Standard deviation (SD)
                                     0.394
Correction factor for censoring (CF)
                                     0.897
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     1.120
- Mean + 4 SD
                                     2.098
- CF x 3 Mean
                                     1.404
Unrounded MRL
                                     2.098
 
                                       
Rounded MRL
                                       2
 
                                       
 
 

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                       2
                                     0.058
                                       1
                                     0.18
                                       1
                                     0.27
                                       1
                                     0.48
                                       1
                                     0.49
                                       1
                                     0.55
                                       1
                                     0.58
                                       1
                                     0.92
                                       1
                                     0.93
                                       1
                                      1.1
                                       1
                                     1.12
                                       1

                                  Metaldehyde
                                    Celery
                                      USA
                            4.0 lb ai/A, 1-day PHI
 
 
Total number of data (n)
                                       8
Percentage of censored data
                                      63%
Number of non-censored data
                                       3
Lowest residue
                                     0.050
Highest residue
                                     0.240
Median residue
                                     0.050
Mean
                                     0.110
Standard deviation (SD)
                                     0.084
Correction factor for censoring (CF)
                                     0.583
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.240
- Mean + 4 SD
                                     0.446
- CF x 3 Mean
                                     0.193
Unrounded MRL
                                     0.446
 
                                       
Rounded MRL
                                      0.5
 
                                       
 High uncertainty of MRL estimate.
[High level of censoring]

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                       5
                                     0.19
                                       1
                                      0.2
                                       1
                                     0.24
                                       1

                                  Metaldehyde
                                     Mint
                                      USA
                            4.0 lb ai/A, 1-day PHI
 
 
Total number of data (n)
                                       5
Percentage of censored data
                                      0%
Number of non-censored data
                                       5
Lowest residue
                                     0.670
Highest residue
                                     2.390
Median residue
                                     0.920
Mean
                                     1.148
Standard deviation (SD)
                                     0.702
Correction factor for censoring (CF)
                                     1.000
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     2.390
- Mean + 4 SD
                                     3.958
- CF x 3 Mean
                                     3.444
Unrounded MRL
                                     3.958
 
                                       
Rounded MRL
                                       4
 
                                       
 High uncertainty of MRL estimate.
[Small dataset]

                               Residues (mg/kg)
                                       n
                                     0.67
                                       1
                                     0.82
                                       1
                                     0.92
                                       1
                                     0.94
                                       1
                                     2.39
                                       1

                                  Metaldehyde
                                  Taro leaves
                                      USA
                             15 lb ai/A, 7-day PHI
 
 
Total number of data (n)
                                       3
Percentage of censored data
                                      33%
Number of non-censored data
                                       2
Lowest residue
                                     0.050
Highest residue
                                     0.400
Median residue
                                     0.057
Mean
                                     0.169
Standard deviation (SD)
                                     0.200
Correction factor for censoring (CF)
                                     0.778
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.400
- Mean + 4 SD
                                     0.969
- CF x 3 Mean
                                     0.394
Unrounded MRL
                                     0.969
 
                                       
Rounded MRL
                                       1
 
                                       
 High uncertainty of MRL estimate.
[Small dataset]

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                       1
                                     0.057
                                       1
                                      0.4
                                       1

                                  Metaldehyde
                                  Taro corms
                                      USA
                             15 lb ai/A, 7-day PHI
 
 
Total number of data (n)
                                       3
Percentage of censored data
                                      67%
Number of non-censored data
                                       1
Lowest residue
                                     0.050
Highest residue
                                     0.085
Median residue
                                     0.050
Mean
                                     0.062
Standard deviation (SD)
                                     0.020
Correction factor for censoring (CF)
                                     0.556
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.085
- Mean + 4 SD
                                     0.142
- CF x 3 Mean
                                     0.103
Unrounded MRL
                                     0.142
 
                                       
Rounded MRL
                                     0.15
 
                                       
 High uncertainty of MRL estimate.
[Small dataset and high level of censoring]

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                       2
                                     0.085
                                       1

                                  Metaldehyde
                                 Corn, stover
                                      USA
                             15 lb ai/A, 7-day PHI
 
 
Total number of data (n)
                                      15
Percentage of censored data
                                      67%
Number of non-censored data
                                       5
Lowest residue
                                     0.050
Highest residue
                                     0.081
Median residue
                                     0.050
Mean
                                     0.056
Standard deviation (SD)
                                     0.010
Correction factor for censoring (CF)
                                     0.556
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.081
- Mean + 4 SD
                                     0.096
- CF x 3 Mean
                                     0.093
Unrounded MRL
                                     0.096
 
                                       
Rounded MRL
                                      0.1
 
                                       
 High uncertainty of MRL estimate.
[High level of censoring]

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                      10
                                     0.06
                                       1
                                     0.063
                                       2
                                     0.073
                                       1
                                     0.081
                                       1

                                  Metaldehyde
                                 Corn, forage
                                      USA
                             15 lb ai/A, 7-day PHI
 
 
Total number of data (n)
                                      15
Percentage of censored data
                                      67%
Number of non-censored data
                                       5
Lowest residue
                                     0.050
Highest residue
                                     0.210
Median residue
                                     0.050
Mean
                                     0.067
Standard deviation (SD)
                                     0.042
Correction factor for censoring (CF)
                                     0.556
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.210
- Mean + 4 SD
                                     0.234
- CF x 3 Mean
                                     0.111
Unrounded MRL
                                     0.234
 
                                       
Rounded MRL
                                      0.3
 
                                       
 High uncertainty of MRL estimate.
[High level of censoring]

                               Residues (mg/kg)
                                       n
                                   < 0.05 
                                      10
                                     0.051
                                       1
                                     0.072
                                       1
                                     0.074
                                       1
                                     0.095
                                       1
                                     0.21
                                       1