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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND

 POLLUTION PREVENTION

MEMORANDUM

Date: 10-JUL-2014

Subject: Metaldehyde. Section 3 Registration for New Uses on Vegetable, Legume, 

Edible Podded [Subgroup 6A], Pea and Bean, Succulent Shelled [Subgroup 6B], 

Vegetable, Foliage of Legume, Except Soybean [Subgroup 7A], Clover Forage

and Hay, and Ginseng; and for Amendments to Existing Tolerances for Tomato 

[Subgroup 8-10A], and Citrus Fruit [Group 10-10]. Summary of Analytical 

Chemistry and Residue Data.

PC Code: 053001 DP Barcode: D418047

Decision No.: 486426 Registration No.: NA

Petition No.: 3E8223 Regulatory Action: Section 3 Registration

Risk Assessment Type: NA Case No.: NA

TXR No.: NA CAS No.: 108-62-3

MRID Nos.: See MRID table below 40 CFR: §180.523

FROM: Austin Doh, Chemist

Risk Assessment Branch (RAB) V/VII

Health Effects Division (HED) (7509P)

THROUGH: William H. Donovan, Ph.D., Chemist

Michael S. Metzger, Branch Chief

RAB V/VII, HED (7509P)

TO: Laura Nollen/Barbara Madden, RM 05

Risk Integration, Minor Use, Emergency Response Branch

Registration Division (7505P)

Table A. MRID Summary Table For Metaldehyde

MRID No. Study Type Comments

49277201 860.1500 edible podded pea and bean field trials 49277201.der.docx

49277203 860.1500 succulent shelled pea field trials 49277203.der.docx

49277204 860.1500 clover field trials 49277204.der.docx

49277205 860.1500 ginseng field trials 49277205.der.docx

49299501 860.1500 succulent shelled bean field trials 49299501.der.docx
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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 vegetable, legume, edible podded (subgroup 6A), pea and 

bean, succulent shelled (subgroup 6B), vegetable, foliage of legume, except soybean, (subgroup 

7A), clover hay, clover forage, and ginseng; and for replacing the existing tolerances for tomato 

with tomato subgroup 8-10A, and replacing citrus, fruit group 10 with fruit, citrus, group 10-10. 

For clover grown for seed, a regional registration (Pacific NW) was requested while national 

registrations are intended for the 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. 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. 

No processed commodities are associated with the new uses proposed in the current petition. A

previously-submitted 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. 

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-CASTM 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 are extracted with dichloromethane 

(DCM), filtered through sodium sulfate, concentrated with rotary evaporation, then brought back 

up to volume with DCM before analysis with GC/MS. The limit of quantitation (LOQ) for 

metaldehyde in/on plant commodities is 0.05 ppm.

An adequate enforcement method is available to enforce recommended tolerances for the 

proposed new uses of metaldehyde.
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2.2.2 Recommended Tolerances

HED has examined the residue chemistry database for metaldehyde. Pending submission of 

revised Sections B (see Section 2.3) 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)] appropriately reads as follows:

Tolerances are established for residues of the molluscicide metaldehyde, its metabolites 

and degradates, in or on the commodities listed in the following table. Compliance with 

the specified tolerance levels 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

Vegetable, legume, edible 

podded, subgroup 6A

0.80 0.80

Pea and bean, succulent 

shelled, subgroup 6B

0.20 0.20

Vegetable, foliage of 

legume, except soybean, 

subgroup 7A

1.50 1.50

Tomato subgroup 8-10A 0.24 0.24

Fruit, citrus, group 10-10 0.26 0.26

Ginseng 0.05 0.05

Note to RD: Upon establishment of the recommended subgroup 8-10A and group 10-10 

tolerances, the existing tomato and group 10 tolerance listings should be deleted.

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

Clover, forage 0.5 0.60 Pacific Northwest

Clover, hay 0.5 0.60 Pacific Northwest
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2.2.3 Revisions to Petitioned-For Tolerances

HED recommends tolerances of 0.60 ppm for clover hay and forage because of the determination 

that only three independent clover trials were conducted instead of the four trials assumed by the 

petitioner. Use of the OECD tolerance calculation procedures with three residue values each for 

clover hay and forage results in suggested tolerances of 0.60 ppm for both commodities. 

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 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)

O

O

O

O

H C3CH3

CH3 H C3
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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/cm3

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 (m3/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.]

Applicat

ion Rate 

(lb ai/A)

Max. No. 

Application 

per Season

Max. 

Seasonal 

Application 

Rate (lb 

ai/A)

PHI (days) Use Directions and 

Limitations

Vegetable, legume, edible podded (Subgroup 6A)

Broadcast 

(ground & 

handheld 

equipment)

71096-13 1.0 3 3 Pre-bloom RTI = 7 days

Pea and Bean, succulent shelled (Subgroup 6B)

Broadcast 

(ground & 

handheld 

equipment)

71096-13 1.0 3 3 Pre-bloom RTI = 7 days

Vegetable, foliage of legume, except soybean (Subgroup 7A)

Broadcast 

(ground & 

handheld 

equipment)

71096-13 1.0 3 3 1 RTI = 7 days

Clover, forage*

Broadcast 

(ground & 

handheld 

equipment)

71096-13 0.8 2 1.6 30 RTI = 10 days

Clover, hay*
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Table 3.3. Summary of Directions for Use of Metaldehyde Granular Formulation

Application 

Timing, Type, 

and Equip.

Formulation 

[EPA Reg. 

No.]

Applicat

ion Rate 

(lb ai/A)

Max. No. 

Application 

per Season

Max. 

Seasonal 

Application 

Rate (lb 

ai/A)

PHI (days) Use Directions and 

Limitations

Broadcast 

(ground & 

handheld 

equipment)

71096-13 0.8 2 1.6 30 RTI = 10 days

Ginseng

Broadcast 

(ground & 

handheld 

equipment)

71096-13 1.0 6 6 21 RTI = 21 days

* For use in the following states: Oregon, Idaho, and Washington

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 [14C]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 [14C]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.
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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 was requested, submitted, and reviewed (see Section 5.3.2). 

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 summarizes the metaldehyde residues of concern for the tolerance 

expression and for risk assessment in the matrices indicated.

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
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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-CASTM 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 are extracted with dichloromethane 

(DCM), filtered through sodium sulfate, concentrated with a TurboVap evaporation apparatus, 

then brought back up to volume with DCM before analysis. Samples were analyzed by GC/MS 

using the m/z 89 and 45 ions for quantitation and confirmation, respectively. Clover hay

samples were allowed to soak in water prior to extraction. The limit of quantitation (LOQ) for 

metaldehyde in/on plant commodities is 0.05 ppm.

Method validation data for the GC/MS method demonstrated adequate method recoveries from 

plant commodities (bean, pea, clover, and ginseng) fortified with metaldehyde at 0.05-5.0 ppm. 

Recoveries were within the acceptable 70-120% range and had standard deviations of < 20%. 

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, 130C) 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-CASTM 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 

clover hay) are extracted with dichloromethane (DCM) containing sodium sulfate, filtered, 

concentrated, and analyzed by GC/MS. Clover hay samples were allowed to soak in water prior 

to extraction. 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.
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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 will expire on January 31st, 2016 [personal communication from T. Cole of 

ACB/BEAD to W. Donovan, 07/10/2014]. 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. Furthermore, additional storage stability data were submitted in 

support of crop field trial data in 2013 (D418047, W. Donovan). In these studies metaldehyde 

was found to be stable for 10.6 months in celery, 18.3 months in corn forage, 6.3 months in corn 

grain, 9.6 months in corn stover, 15.9 months in grass (forage, hay), 10.5 months in mint leaf, 

24.2 months in mint oil, 7.8 months in soybean seed, 12.4 months in taro leaf and corm, 14.8 

months in radish (roots, tops), sorghum (forage, grain, stover) and wheat (forage, hay, grain and 

straw).

In support of the crop field trial data submitted for the proposed new uses of metaldehyde,

concurrent storage stability studies were conducted for bean, pea, clover and ginseng. 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 

Bean Edible Pod

≤ 0

346 366

Shelled Succ. 459 442

Foliage 355 366

Pea Edible Pod 351 368

Shelled Succ. 277 279

Foliage 371 368
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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)

Clover Hay 666 670

Forage 530 552

Ginseng Root 412 430

Thus, metaldehyde is stable in frozen storage for at least 7.7 months in bean (pod and foliage), 

10.0 months in pea (pod and foliage), 12.9 months in bean (succulent shelled), 2.9 months in pea 

(succulent shelled), 13.6 months in clover forage, 18.3 months in clover hay, and 14.1 months in 

ginseng. 

5.3 Residue Data

5.3.1 Crop Field Trials (860.1500)

49277201.der (Bean and pea, edible podded)

49277203.der (Pea, succulent shelled)

49277204.der (Clover)

49277205.der (Ginseng)

49299501.der (Bean, succulent shelled)

The crop field trial data submitted in support of this petition were generated by IR-4. 

Bean and Pea (Edible Podded) Field Trials [Subgroups 6A and 7A]

Seven bean trials were conducted in the North American Free Trade Agreement (NAFTA) 

Growing Zone 1 (NY; 1 trial), 2 (NC; 1 trial), 3 (FL; 1 trial), 5 (OH and WI; 2 trials), 10 (CA; 1 

trial), and 11 (WA; 1 trial); and three pea trials were conducted in Zones 2 (GA; 1 trial), 10 (CA; 

1 trial), and 11 (ID; 1 trial). 

Each trial consisted of one untreated plot and one treated plot. At each trial location, the treated 

plots received three soil broadcast applications of a 4% mini-pelleted (P/T) formulation of 

metaldehyde (Deadline® M-PsTM) at 0.99-1.00 lb ai/A/application, with a 6- to 8-day retreatment 

interval (RTI), for a total seasonal rate of 2.99-3.01 lb ai/A. Applications were made during 

cotyledon through vegetative stages of development using soil broadcast applications. No 

adjuvants were used with these types of applications. Bean and pea were harvested at pre 

harvest intervals (PHIs) of 30-97 days to evaluate edible podded bean, 1-22 days to evaluate 

bean foliage, 39-55 days to evaluate edible podded peas and 1-35 days to evaluate pea foliage. 

Residue decline was not evaluated.

Residues of metaldehyde were found in all but one of the pea trials, and all but three of the bean 

(podded) trials. A summary of the field trial results is shown in Table 5.3.1.1, below.
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TABLE 5.3.1.1 Summary of Residue Data from Crop Field Trials with Metaldehyde. 

Commodity Total 

Rate 

(lb ai/A)

PHI 

(days)

Residue Levels1

(ppm)

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Bean, edible podded 2.988-

3.012

30-97 7 <0.05 0.432 <0.05 0.347 0.0508 0.159 0.140

Bean, foliage 1-22 7 0.0600 0.668 0.0827 0.647 0.172 0.269 0.222

Pea, edible podded 2.997-

3.000

39-55 3 <0.05 0.258 <0.05 0.252 0.0970 0.133 0.105

Pea, foliage 1-35 3 <0.05 0.352 <0.05 0.330 0.208 0.196 0.140

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 LOQ of 0.05 ppm was used for any results reported as <LOQ.

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of bean 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 edible podded and foliage data sets were analyzed using the OECD tolerance 

calculation procedures to determine a recommended tolerance level of 0.8 ppm for edible podded 

bean, 0.6 ppm for edible podded pea; 1.5 ppm for bean foliage, and 0.8 ppm for pea foliage. The 

higher value for the subgroup was selected for tolerance determination, giving a recommended 

tolerance of 0.8 ppm for edible podded (subgroup 6A) and 1.5 ppm for foliage matrices

(subgroup 7A) (see Appendix C). 

Bean (Succulent Shelled) Field Trials [Subgroup 6B]

A total of 6 field trials were conducted in the United States during the 2011 growing season in 

the NAFTA Growing Zone 2 (MD and NC; 3 trials), 5 (MI; 1 trial), 10 (CA; 1 trial) and 11 (ID; 

1 trial). The two Clinton, NC trials were considered independent due to the use of different lima 

bean varieties (Thorogreen [NC13] and Fordhook 242 [NC14]) and a difference in application 

timing of approximately 3 weeks.

Each trial consisted of one untreated plot and one treated plot. At each trial location, the treated 

plots received three soil broadcast applications of a 4% mini-pelleted (P/T) formulation of 

metaldehyde (Deadline® M-PsTM) at 1.00 lb ai/A/application, with a 6- to 8-day RTI, for a 

seasonal rate of 3.00 lb ai/A. Applications were made during cotyledon through vegetative 

stages of development using ground equipment. No adjuvants were used with these types of 

applications. Beans (succulent shelled) were harvested at PHIs of 48-83 days. Residue decline 

was not evaluated.

Residues of metaldehyde were found in 2 bean (succulent shelled) 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 ai/A)

PHI 

(days)

Residue Levels1

(ppm)

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Beans (succulent 

shelled)

2.99-

3.00

48-83 6 <0.05 0.152 <0.05 0.139 0.050 0.068 0.035

1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 
Metaldehyde Summary of Analytical Chemistry and Residue Data D418047

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standard deviation, the LOQ of 0.05 ppm was used for any results reported as <LOQ.

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of bean 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 succulent shelled bean data were analyzed using the OECD tolerance 

calculation procedures to determine the recommended tolerance level of 0.20 ppm (see Appendix 

C). 

Pea (Succulent Shelled) Field Trials [Subgroup 6B]

A total of 7 field trials on pea were conducted in the United States during the 2010 growing 

season in NAFTA Growing Zones 1 (NY; 1 trial), 5 (MI, OH, and WI; 3 trials), 10 (CA; 1 trial), 

11 (ID; 1 trial) and 12 (OR; 1 trial).

Each trial consisted of one untreated plot and one treated plot. At each trial location, the treated 

plots received three soil broadcast applications of a 4% mini-pelleted (P/T) formulation of 

metaldehyde (Deadline® M-PsTM) at 1.00-1.08 ai/A/application, with a 6- to 8-day retreatment 

interval (RTI), for a total seasonal rate of 3.00-3.25 lb ai/A. Applications were made during 

newly emerged through vegetative stages of development using ground equipment. No 

adjuvants were used with these types of application. Pea (succulent shelled) was harvested at 

preharvest intervals (PHIs) of 21-125 days. Residue decline was not evaluated.

Residues of metaldehyde were found in 4 pea 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 Levels1

(ppm)

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Pea (succulent

shelled)

2.997-3.246 21-125 7 <0.05 0.140 <0.05 0.130 0.083 0.080 0.031

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 LOQ of 0.05 ppm was used for any results reported as <LOQ.

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of pea 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 succulent shelled pea data were analyzed using the OECD tolerance 

calculation procedures to determine the recommended tolerance level of 0.20 ppm. 

As both studies conducted on succulent shelled legumes (bean and pea) resulted in suggested

tolerances of 0.2 ppm, the recommended tolerance for subgroup 6B is 0.20 ppm (see Appendix 

C). 

Clover Field Trials

A total of 3 field trials on clover were conducted in the United States during the 2009 growing 
Metaldehyde Summary of Analytical Chemistry and Residue Data D418047

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season in NAFTA Growing Zones 11 (WA, 1 trial) and 12 (OR, 2 trials). The submitted study

report indicated that three trials were conducted in OR (OR14, OR15, and OR16). However, 

consideration of the trial conditions showed that trials designated OR15 and OR16 are not 

independent; instead they are replicate treatments at one trial site. The soil types and clover 

varieties were identical in OR15 and OR16 and the only difference noted was a one week 

separation in application dates. Trial OR14 was considered independent from OR15 and OR16

due to the different soil characteristics as compared to those in the other plots. 

Each trial consisted of one untreated plot and one treated plot. At each trial location, the treated 

plots received two broadcast soil applications of a 4% mini-pelleted (P/T) bait of metaldehyde 

(Deadline® M-PsTM) at 0.80-0.84 lb ai/A/application, with a 10- to 12-day RTI, for a total 

seasonal rate of 1.60-1.66 lb ai/A. Applications were made during vegetative to blooming stages 

of development. No adjuvants were used with these types of application. Clover forage was 

harvested at PHIs of 23-29 days. Clover hay was harvested at PHIs of 29-51 days and was 

allowed to dry for 5-8 days prior to collection. Residue decline was not evaluated.

Residues of metaldehyde were found in all 3 clover trials. 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 Levels1

(ppm)

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Clover (hay) 1.598-1.661 23-29 3 <0.05 0.275 0.053 0.235 0.165 0.151 0.110

Clover (forage) 1.598-1.661 29-51 3 <0.05 0.255 <0.05 0.241 0.050 0.114 0.092

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 LOQ of 0.05 ppm was used for any results reported as <LOQ.

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of clover field trials and their geographical distribution are adequate for the 

requested regional registration limited to the Pacific Northwest. The samples were analyzed 

using a suitable method and the sample storage intervals are supported by storage stability data. 

The clover forage and hay data were analyzed separately using the OECD tolerance calculation 

procedures. For both matrices, the recommended tolerance was determined to be 0.60 ppm (see 

Appendix C). 

Ginseng Field Trials

A total of 4 crop field trials on ginseng were conducted in the United States during the 2011

growing season in NAFTA Growing Zone 5 (WI; 4 trials). Because the field trial sites were 

separated by ~16-27 miles and had different soil types (loam, silt loam, loamy sand, and sandy

loam), they are considered independent trials. 

Each trial consisted of one untreated plot and one treated plot. At each trial location, the treated 

plots received six foliar broadcast applications of a 4% mini-pelleted (P/T) formulation of 

metaldehyde (Deadline® M-PsTM) at 1.0 lb ai/A/application, with a 20- to 22-day RTI, for a total 

seasonal rate of 6.0 lb ai/A. Applications were made during vegetative through fruiting stages of 
Metaldehyde Summary of Analytical Chemistry and Residue Data D418047

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development using ground equipment. No adjuvants were used with these types of application. 

Ginseng was harvested at PHIs of 21-22 days and was allowed to dry (drying period not 

reported). Samples were collected at PHIs of 7, 14, 21, and 28 days from one trial to assess 

residue decline. No detectable residue levels were found in any ginseng sample; thus, no residue 

decline pattern was discernible. 

Residues of metaldehyde were not found in any of the trials above the LOQ of 0.05 ppm. A 

summary of the field trial results is shown in Table 5.3.1.5, below.

TABLE 5.3.1.5. Summary of Residue Data from Crop Field Trials with Metaldehyde. 

Commodity Total Rate 

lb a.i./A 

PHI 

(days)

Residue Levels1

(ppm)

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Ginseng (root) 6.0 21-22 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 LOQ of 0.05 ppm was used for any results reported as <LOQ.

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

The number of ginseng 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. No detectable residue levels were found in any ginseng sample; thus, the 

recommended tolerance level of 0.05 ppm was based on the analytical method LOQ.

Tomato [Subgroup 8-10A] and Citrus [Group 10-10] proposal

Tolerances are established for metaldehyde on tomato at 0.24 ppm and on Fruit, citrus, group 10 at 

0.26 ppm. On December 8, 2010, the Federal Register published a final rule with revisions to the 

fruiting vegetables crop group and the citrus fruit crop group. HED concludes that it is appropriate to 

translate the established tolerance levels for tomato and citrus, fruit, group 10 to tomato subgroup 8-

10A and citrus, fruit, group 10-10, respectively; and then to remove the tolerance listings for tomato 

and group 10.

5.3.2 Field Rotational Crops (860.1900)

D408745, W. Donovan, 12-JUL-2013

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-CASTM No. ENC-3/99, Revision 1. The following plant matrices were 

analyzed for residues of metaldehyde: radish – tops and roots; sorghum – forage, grain, and 
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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 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) 

5.3.4 Meat, Milk, Poultry and Eggs (860.1480)

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

Committee: Metaldehyde, 3/11/97).

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. 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. No processed commodities are associated with the new uses proposed in the 

current petition. Limited rotational crop field trial studies have demonstrated 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 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 (ginseng), and 3) direct translation where 

appropriate (subgroup 8-10A and group 10-10). 

List of Appendices

A. Number of Crop Field Trials and Geographical Distributions.

B. International Residue Limits Table.

C. Tolerance Calculations.
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Appendix A

TABLE A.1.1. Trial Numbers and Geographical Locations.

NAFTA 

Growing 

Zones

Bean Pea

Submitted Requested1Submitted Requested2

Canada U.S. Canada U.S.

1 1 -- 1/1 -- -- --

1A -- -- -- -- -- --

2 1 -- 1/1 1 -- --

3 1 -- 1/1 -- -- --

4 -- -- -- -- -- --

5 2 -- 3/2 -- -- --

5A -- -- -- -- -- --

5B -- -- -- -- -- --

6 -- -- -- -- -- --

7 -- -- -- -- -- --

7A -- -- -- -- -- --

8 -- -- -- -- -- --

9 -- -- -- -- -- --

10 1 -- 1/0 1 -- --

11 1 -- 1/1 1 -- --

12 -- -- -- -- -- --

13 -- -- -- -- -- --

14 -- -- -- -- -- --

15 -- -- -- -- -- --

16 -- -- -- -- -- --

17 -- -- -- -- -- --

18 -- -- -- -- -- --

19 -- -- -- -- -- --

20 -- -- -- -- -- --

21 -- -- -- -- -- --

Total 7 -- 8/6 3 -- 3

1

 As per OCSPP 860.1500, Tables 1, 3, and 5. 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

 Geographic representation is not specified for crops requiring ≤3 trials.
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TABLE A.1.2. Trial Numbers and Geographical Locations.

NAFTA Growing Regions Bean (succulent shelled)

Submitted Requested1

Canada U.S.

1 -- -- --

1A -- --

2 3 -- 4/3

3 -- -- --

4 -- -- --

5 1 -- 1/1

5A -- -- --

5B -- -- --

6 -- -- --

7 -- -- --

7A -- -- --

8 -- -- --

9 -- -- --

10 1 -- 2/1

11 1 -- 1/1

12 -- -- --

13 -- -- --

14 -- -- --

15 -- -- --

16 -- -- --

17 -- -- --

18 -- -- --

19 -- -- --

20 -- -- --

21 -- -- --

Total 6 8/6

1 As per Table 5 of 860.1500 for bean, lima, green; the second number reflects a 25% reduction in the number of field 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. 
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TABLE A.1.3. Trial Numbers and Geographical Locations.

NAFTA Growing Regions Pea (Succulent Shelled)

Submitted Requested1

Canada U.S.

1 1 -- 1/12

1A -- --

2 -- -- 1/12

3 -- -- --

4 -- -- --

5 3 -- 4/3

5A -- -- --

5B -- -- --

6 -- -- --

7 -- -- --

7A -- -- --

8 -- -- --

9 -- -- --

10 1 -- --

11 1 -- 2/1

12 1 -- 1/1

13 -- -- --

14 -- -- --

15 -- -- --

16 -- -- --

17 -- -- --

18 -- -- --

19 -- -- --

20 -- -- --

21 -- -- --

Total 7 8/6

1 As per Table 5 of 860.1500 for pea, garden, succulent; the second number reflects a 25% reduction in the number of field 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 Either region is acceptable.
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TABLE A.1.4. Trial Numbers and Geographical Locations.

NAFTA Growing Regions Clover

Submitted Requested

Canada U.S.

1 -- -- 1/1

1A -- --

2 -- -- 1/1

3 -- -- --

4 -- -- 1/1

5 -- -- 3/2

5A -- -- --

5B -- -- --

6 -- -- 1/1

7 -- -- 1/1

7A -- -- --

8 -- -- 1/1

9 -- -- 1/0

10 -- -- 1/11

11 1 -- 1/11

12 2

2

-- --

13 -- -- --

14 -- -- --

15 -- -- --

16 -- -- --

17 -- -- --

18 -- -- --

19 -- -- --

20 -- -- --

21 -- -- --

Total 3

3

12/9

1 Either region is acceptable.

2 HED has concluded that two trials (OR 15 and OR 16) conducted in Aurora, OR (Zone 12) should constitute a single trial with 

replicate samples for the purpose of 860.1500 data requirements, while trial OR14 is independent.

3 This study is to support a regional registration in the Pacific Northwest on clover grown for seed.
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TABLE A.1.5. Trial Numbers and Geographical Locations.

NAFTA Growing Regions Ginseng

Submitted Requested1

Canada U.S.

1 -- -- --

1A -- --

2 -- -- --

3 -- -- --

4 -- -- --

5 4 -- --

5A -- -- --

5B -- -- --

6 -- -- --

7 -- -- --

7A -- -- --

8 -- -- --

9 -- -- --

10 -- -- --

11 -- -- --

12 -- -- --

13 -- -- --

14 -- -- --

15 -- -- --

16 -- -- --

17 -- -- --

18 -- -- --

19 -- -- --

20 -- -- --

21 -- -- --

Total 4 3 or 2

1 As per OPPTS 860.1500, Table 1 for ginseng; trial locations are not specified for crops requiring ≤3 field trials. According to 

“Food and Feed Crops of the United States” (G.M. Markle, J.J. Baron, and B.A. Schneider. Second Edition, Meister Publishing 

Co. 1998), ginseng is grown in Zones 1, 2, 4, and 5 with Zone 5 being the major cultivated region.
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Appendix B. International Residue Limits Table

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 Mexico2 Codex

40 CFR 180.523:

Plant: Metaldehyde

None None

Commodity1

Recommended Tolerance (ppm) /Maximum Residue Limit 

(mg/kg)

US Canada Mexico2 Codex

Vegetable, legume, edible podded, 

subgroup 6A

0.80

Pea and bean, succulent shelled, 

subgroup 6B

0.20

Vegetable, foliage of legume, except 

soybean, subgroup 7A

1.50

Tomato subgroup 8-10A 0.24

Fruit, citrus, group 10-10 0.26

Clover, forage 0.60

Clover, hay 0.60

Ginseng 0.05

Completed: M. Negussie; 06/18/14

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.
Page 22 of 29

Appendix C. Results of OECD Tolerance Calculations

Metaldehyde

Bean (Succulent Shelled)

USA

1 lb ai/A, 3 aps

Total number of data (n) 6

Percentage of censored data 67%

Number of non-censored data 2

Lowest residue 0.050

Highest residue 0.139

Median residue 0.050

Mean 0.068

Standard deviation (SD) 0.035

Correction factor for censoring (CF) 0.556

Proposed MRL estimate

- Highest residue 0.139

- Mean + 4 SD 0.210

- CF x 3 Mean 0.113

Unrounded MRL 0.210

Rounded MRL 0.2

High uncertainty of MRL estimate.

[High level of censoring]

Residues (mg/kg) n

0.139 1

0.069 1

0.050 4
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Metaldehyde

Bean (Pods with Seed)

USA

1.0 lb ai/A, 3 aps

Total number of data (n) 7

Percentage of censored data 43%

Number of non-censored data 4

Lowest residue 0.050

Highest residue 0.347

Median residue 0.051

Mean 0.159

Standard deviation (SD) 0.140

Correction factor for censoring (CF) 0.714

Proposed MRL estimate

- Highest residue 0.347

- Mean + 4 SD 0.718

- CF x 3 Mean 0.340

Unrounded MRL 0.718

Rounded MRL 0.8

High uncertainty of MRL estimate.

[Small dataset]

Residues (mg/kg) n

0.05 3

0.347 1

0.33 1

0.2325 1

0.05075 1
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Metaldehyde

Bean (Foliage)

USA

1.0 lb ai/A, 3 aps

Total number of data (n) 7

Percentage of censored data 0%

Number of non-censored data 7

Lowest residue 0.080

Highest residue 0.647

Median residue 0.172

Mean 0.268

Standard deviation (SD) 0.222

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.647

- Mean + 4 SD 1.155

- CF x 3 Mean 0.805

Unrounded MRL 1.155

Rounded MRL 1.5

High uncertainty of MRL estimate.

[Small dataset]

Residues (mg/kg) n

0.080 1

0.088 1

0.172 1

0.502 1

0.264 1

0.127 1

0.647 1
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Metaldehyde

Pea (Succulent Shelled)

USA

1.0 lb ai/A, 3 aps

Total number of data (n) 7

Percentage of censored data 43%

Number of non-censored data 4

Lowest residue 0.050

Highest residue 0.130

Median residue 0.082

Mean 0.080

Standard deviation (SD) 0.031

Correction factor for censoring (CF) 0.714

Proposed MRL estimate

- Highest residue 0.130

- Mean + 4 SD 0.206

- CF x 3 Mean 0.171

Unrounded MRL 0.206

Rounded MRL 0.2

High uncertainty of MRL estimate.

[Small dataset]

Residues (mg/kg) n

0.05 3

0.1295 1

0.08245 1

0.0947 1

0.1035 1
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Metaldehyde

Pea (Pods with Seed)

USA

1.0 lb ai/A, 3 aps

Total number of data (n) 3

Percentage of censored data 33%

Number of non-censored data 2

Lowest residue 0.050

Highest residue 0.252

Median residue 0.097

Mean 0.133

Standard deviation (SD) 0.105

Correction factor for censoring (CF) 0.778

Proposed MRL estimate

- Highest residue 0.252

- Mean + 4 SD 0.555

- CF x 3 Mean 0.310

Unrounded MRL 0.555

Rounded MRL 0.6

High uncertainty of MRL estimate.

[Small dataset]

Residues (mg/kg) n

< 0.05 1

0.097 1

0.2515 1
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Metaldehyde

Pea (Foliage)

USA

1.0 lb ai/A, 3 aps

Total number of data (n) 3

Percentage of censored data 33%

Number of non-censored data 2

Lowest residue 0.050

Highest residue 0.330

Median residue 0.208

Mean 0.196

Standard deviation (SD) 0.140

Correction factor for censoring (CF) 0.778

Proposed MRL estimate

- Highest residue 0.330

- Mean + 4 SD 0.758

- CF x 3 Mean 0.457

Unrounded MRL 0.758

Rounded MRL 0.8

High uncertainty of MRL estimate.

[Small dataset and high level of censoring]

Residues (mg/kg) n

0.050 1

0.330 1

0.208 1
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Metaldehyde

Clover (Forage)

Pacific NW - USA

0.8 lb ai/A, 2 aps

Total number of data (n) 3

Percentage of censored data 0%

Number of non-censored data 3

Lowest residue 0.053

Highest residue 0.235

Median residue 0.165

Mean 0.151

Standard deviation (SD) 0.092

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.235

- Mean + 4 SD 0.519

- CF x 3 Mean 0.453

Unrounded MRL 0.519

Rounded MRL 0.6

High uncertainty of MRL estimate.

[Small dataset and High level of censoring]

Residues (mg/kg) n

0.165 1

0.053 1

0.235 1
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Metaldehyde

Clover (Hay)

USA

0.8 lb ai/A, 2 aps

Total number of data (n) 3

Percentage of censored data 67%

Number of non-censored data 1

Lowest residue 0.050

Highest residue 0.241

Median residue 0.050

Mean 0.114

Standard deviation (SD) 0.110

Correction factor for censoring (CF) 0.556

Proposed MRL estimate

- Highest residue 0.241

- Mean + 4 SD 0.553

- CF x 3 Mean 0.189

Unrounded MRL 0.553

Rounded MRL 0.6

High uncertainty of MRL estimate.

[High level of censoring]

Residues (mg/kg) n

0.050 2

0.241 1