.#'f.f>"1"4~~ 

~~ _) 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: March 29, 2016 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Dicamba. Section 3 Registration for the Amended Use ofDicamba on Dicamba-Tolerant 

Cotton. Summary of Analytical Chemistry and Residue Data. 

PC Code: 02980 1. 029802. 029806, 128931 , 128944, 

& 129043 

Decision No.: 467997 

Petition No.: 2F8067 

Risk Assessment Type: NA 

TXR No.: NA 

MRIO Nos.: 48728701-48728704 

FROM: Peter Savoia. Chemist OA--le L 

Risk Assessment Branch VN II 

OP Barcode: 0 408384 

Rc2istration No.: 524-582 

Regulatory Actioi1: Amended Section 3 Registration 

Case No.: 0065 

CAS No.: 1918-00-9 

40 CFR: § 180.227 

Health Effects Division (7509P) ) ., 

THRU: Michael S. Metzger, Branch Chief ~ t-.ltf.<_ I }, 

TO: 

Donna S. Davis, Chemist 

Risk Assessment Branch V/VII 

Health Effects Division (7509P) 

William A. Irwin, Risk Assessor 

Risk Assessment Branch VN II 

Health Effects Division (7509P) 

And 

Kathryn Montague/Michael Walsh, Risk Manager 

Herbicide Branch 

Registration Division (7505P) 

Executive Summary 

Monsanto has submitted petition PP#2F8067 requesting Section 3 registration for the amended use of 

dicamba on dican1ba-tol erant cotton. Monsanto is requesting to amend the cotton undelinted seed 

tolerance from 0.2 ppm to 3.0 ppm and establish a new tolerance for cotton gin byproducts at 70.0 

ppm. Dicamba is a selecti ve benzoic acid herbicide used for controlling weeds prior to their 

emergence. It is available for use in either acid or salt forms with registered uses being maintained on 

a wide variety of crop and livestock commodities. Permanent tolerances are established under 40 

CFR § l 80.227(a)(l) for dicamba and its 3,6-dichloro-5-hydroxybenzoic ac id (5-0H dicamba) 

metabolite. Additional tolerances are established under 40CFR§180.227(a)(2) for dicamba and its 

3,6-dichloro-2-hydroxybenzoic acid (also known as 3.6-diclorosalicyclic acid or DCSA) metabolite, 

as well as under 40 CFR § J 80.227(a)(3) for dicamba, 5-0H dicamba, and the DCSA metabolite. 

Page I of26 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 2 of 26

Dicamba is registered for pre-plant application on cotton but not for post-emergence treatment 

because crop injury could occur if it were to come in contact with cotton roots, stems, or foliage. To 

enable post-emergence application, Monsanto has developed a dicamba-tolerant variety of cotton 

(MON 88701) capable of receiving treatment up to seven days before harvest. The M1691 Herbicide 

(EPA Reg. No. 524-582) soluble liquid concentrate (SL) diglycolamine salt formulation of dicamba is 

proposed for use on dicamba-tolerant cotton. For pre-emergent application, up to 32 fluid ounces of 

the M1691 herbicide (1.0 lb ae/A) may be used for pre-plant or at planting prior to crop emergence. 

Using a maximum single in crop application of up to 16 fluid ounces per acre (0.5 lb ae/A), postemergence treatments are also allowed not to exceed the seasonal total in a given year. Applications 

are to be made following a 7-day re-treatment interval (RTI) and a 7-day pre-harvest interval (PHI). 

A combined total of all applications is not to exceed 64 fluid ounces per acre (2.0 lb ae/A) in a given 

year. 

Previously submitted wheat, grape, asparagus, sugarcane, cotton, and soybean metabolism studies 

demonstrate that dicamba is metabolized in plants by demethylation and hydroxylation. A new 

metabolism study on dicamba-tolerant cotton shows a generally similar metabolic pathway to other 

plants; however, when compared to cotton which is not dicamba-tolerant, significantly more DCSA is 

found with the dicamba-tolerant cotton. Therefore, the newly submitted metabolism study supports 

including parent, 5-OH dicamba, as well as the DCSA metabolite as the residues of concern for 

dicamba-resistant cotton for both tolerance setting purposes and risk assessment. Based on 

previously submitted metabolism studies on ruminants and poultry, the nature of the residue in 

livestock commodities for tolerance setting purposes and risk assessment is adequately understood to 

be dicamba and DCSA. 

There are adequate methods available for the enforcement of the newly proposed cotton seed and 

cotton gin byproducts tolerances. PAM Vol. II Method I using Gas Chromatography/Electron 

Capture Detection (GC/ECD) analyses is adequate for enforcement. New tolerances are not proposed 

for animal commodities; therefore a discussion of animal enforcement methods is not relevant to this 

petition. Dicamba is recoverable through the FDA multi-residue method (MRM) testing protocols, 

but no data have been provided for any of its regulated metabolites. However, single analyte methods

are available for enforcement and additional MRM data are not needed.

The number and locations of the field trial studies submitted for dicamba-resistant cotton were in 

accordance with the OCSPP 860.1500 test guidelines. The data were generated using a validated data 

collection method and are supported by adequate storage stability data. Total residues of dicamba 

and its metabolites 5-OH dicamba, and DCSA, expressed as parent equivalents, ranged from 0.11 

ppm to 1.72 ppm in dicamba-resistant cotton undelinted seed treated at a maximum seasonal 

application rate of 2.0 lbs ae/A with a single late-season foliar application of 0.5 lbs ae/A and a PHI 

of 7-days. For gin byproducts in dicamba-tolerant cotton, total residues of dicamba ranged from 5.06 

ppm to 29.6 ppm following this same pattern of use.

An adequate processing study was submitted. Residue data was generated using an adequately 

validated data collection method. Samples were analyzed within 30-days; therefore, storage stability 

data is not required. Residues of dicamba, 5-OH dicamba, and DCSA did not concentrate in any 

processed fraction. 

The residue values obtained from these field trial studies and the processing study were evaluated 

using the Organization for Economic Cooperation and Development (OECD) calculation procedures 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 3 of 26

for estimating tolerances/Maximum Residue Limits (MRLs). Using the OECD calculation 

procedures, and inputting the total residue, which includes the parent compound, and its metabolites 

5-OH dicamba, and DCSA, expressed as parent, recommended tolerances of 3.0 ppm for cotton 

undelinted seed and 70.0 ppm for cotton gin byproducts are appropriate.

For this action, the establishment of a tolerance on cotton gin byproducts will not increase livestock 

dietary burden; therefore, no new revised tolerances on livestock commodities are required to support 

this petition. 

There are MRLs of 0.2 ppm in Mexico and 0.04 ppm established by Codex on cotton seed currently 

established. There are currently no Mexican, Canadian or Codex MRLs established for cotton gin 

byproducts. Since the registrant has requested a late season use of dicamba on dicamba-tolerant

cotton, the currently established international tolerances are not adequate to cover residues likely 

from the newly proposed use in the U.S. In addition, the dicamba residues of concern for dicambatolerant cotton also include the DCSA metabolite which is not found nor regulated in the other 

common varieties of cotton. Therefore, harmonization is not possible at this time for cotton seed. 

Since there are no international tolerances on cotton gin byproducts, there is no issue of international 

harmonization relevant to that tolerance. 

The December 2005 Reregistration Eligibility Decision (RED) for dicamba requires additional 

rotational crop studies in order to satisfy data requirements. However, these data are not needed if a 

120-day plantback interval is specified when dicamba is applied at the maximum seasonal rate of 

0.75 lb ae/A. For greater seasonal application rates of 0.75-2.0 lb ae/A, only crops with established 

tolerances can be rotated for planting. No new rotational crop data have since been submitted; 

therefore, the plantback restrictions noted in the 2005 RED are appropriately specified on the product 

label for treating dicamba-tolerant cotton; and additional rotational crop data are not needed at this 

time.

Regulatory Recommendations and Residue Chemistry Deficiencies

Provided the label is amended as specified below, there are no residue chemistry deficiencies that 

preclude establishing permanent tolerances on cotton raw agricultural commodities (RACs) for 

dicamba. A revised human health risk assessment to support the requested use on dicamba-resistant 

cotton is forthcoming. 

The tolerance expressions specified in the CFR for dicamba are in compliance with HED’s Interim 

Guidance on Tolerance Expressions (05/27/2009, S.Knizner). For this action, the recommended 

dicamba tolerances for cotton RACs are to be set under 40 CFR §180.227(a)(3) as follows: 

Tolerances are established for residues of the herbicide dicamba, 3,6-dichloro-o-anisic acid, including 

its metabolites and degradates, in or on the commodities in the table below. Compliance with the 

tolerance levels is to be determined by measuring only the residues of dicamba, 3,6-dichloro-o-anisic 

acid, and its metabolites, 3,6-dichloro-5-hydroxy-o-anisic acid, and 3,6-dichloro-2-hydroxybenzoic 

acid, calculated as the stoichiometric equivalent of dicamba, in or on the following commodities:

Cotton, gin byproducts.......................................................70.0 ppm

Cotton, undelinted seed........................................................3.0 ppm
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 4 of 26

Note to RD

The 40 CFR §180.227(a)(1) citation for dicamba currently lists a 0.2 ppm tolerance for cotton,

undelinted seed. This entry in the CFR should be removed, and replaced with the tolerances shown 

above under 40 CFR §180.227(a)(3). 

860.1200 Directions for Use

An amended Section B is required noting that no more than two (2) post-emergence applications may 

be made past the first open boll stage when treating dicamba-tolerant cotton is allowed.

Background

Dicamba, 3,6-dichloro-2-methoxybenzoic acid, is a selective benzoic acid herbicide registered for 

controlling a wide variety of broadleaf weeds and woody plants prior to their emergence. It has 

similar hormonal properties to natural auxins which induce abnormal and uncontrollable growth to 

disrupt normal plant functions at high concentrations. Dicamba end-use products are available as

either acid or salt formulations with registered uses being maintained on a wide variety of crop and 

livestock commodities. The chemical structure and nomenclature of dicamba and its metabolites 5-

OH dicamba, and DSCA are presented in Table 1. The physicochemical properties of the technical 

grade of dicamba acid are presented in Table 2. 

Table 1. Test Compound Nomenclature: Dicamba and its Residues of Concerm.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Clarity® Herbicide: SL formulation containing 4 lb ae/gal

Compound

Common name 5-Hydroxy-dicamba

Company experimental name 5-OH dicamba

IUPAC/CAS name 2,5-dichloro-3-hydroxy-6-methoxybenzoic acid

CAS registry number 7600-50-2
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 5 of 26

Table 1. Test Compound Nomenclature: Dicamba and its Residues of Concerm.

Compound

Common name DCSA; 3,6-dichlorosalicylic acid

Company experimental name MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7

Table 2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED (D317699, C. L. Olinger, 

12/20/2005). pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)

860.1200 Directions for Use

The dicamba product used for treating dicamba-tolerant cotton proposed for registration is the M1691 

Herbicide (EPA Reg. No. 524-582) which is a soluble liquid concentrate (SL) formulation. This end–

use product contains 56.8% active ingredient in the form of the diglycolamine salt of dicamba

(equivalent to 4.0 lb ae/gal). A summary of the proposed directions for use taken directly from the 

supplemental M1691 herbicide label provided by the registrant are presented below in Table. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 6 of 26

Table 3. Summary of Directions for Use of Dicamba.

Formulation 

[EPA Reg. 

No.]

Applic. 

Timing, 

Type, and 

Equip.

Max. 

Applic. 

Rate

(lb ae1/A)

Max. 

No. 

Applic. 

per 

Season

Max. 

Seasonal 

Applic. Rate

(lb ae/A)

Combined 

Max. Seasonal 

Applic. Rate

(lb ae/A)

RTI2

(days)

PHI3

(days)

Use Directions 

and Limitations4

MON 88701 Cotton

M1691

4.0 lb ae/gal 

SL

[524-582]

Pre-plant, 

at planting, 

and Preemergence

Broadcast 

(20 gal/A)

1.0 NS5 1.0 2.0 7 7 Use of a COC or 

MSO is not 

recommended 

with Roundup 

branded

herbicides. These 

adjuvants are only 

used when other 

products require 

them. For best 

results apply at 

min spray rate of 

10 GPA. Apply 

with ground 

equipment only; 

aerial application 

is prohibited.

Postemergence, 

Broadcast

(20 gal/A)

0.5 NS 2.0

1

 ae = Acid Equivalents

2

 RTI = Re-Treatment Interval

3

 PHI = Pre-Harvest Interval

4

 COC = Crop Oil Concentrate; MSO = Methylated Seed Oil.

5 NS = Not Specified

Conclusions. The proposed directions for use were compared to the submitted field trial data. The 

field trial studies were conducted covering the expected range of applications allowed under the 

proposed label. This includes pre-emergent applications of up to 1.0 lb ae/A, as well as multiple 

early to late post-emergent treatments of up to 0.5 lb ae/A each for a combined annual total of 2.0 lb 

ae/A. Treatments may include the use of adjuvants and can be re-applied following a 7-day RTI and 

a 7-day PHI. As such, the product label allows growers great flexibility in using dicamba to control 

weeds when cultivating cotton. The residue data provided examining this broad pattern of use shows 

that later post-emergence treatments give much higher residues then those made at earlier growth 

stages. Following the pattern of late season use demonstrated by the field trial data, no more than two 

(2) post-emergence applications may be made after the first open boll stage when treating dicambatolerant cotton. Therefore, the registrant should amend the product label to include this restriction 

since the data provided only support this pattern of use.

860.1300 Nature of the Residue - Plants

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

DER Reference: 48728701.der.docx (Nature of the Residue in Dicamba-Tolerant Cotton)

For non-dicamba resistant plants, the nature of the residue was previously determined to be 

understood (D317699, C. L. Olinger, 12/20/2005). Prior plant metabolism studies were reviewed in 

part with the 1983 residue chemistry chapter of the dicamba registration standard. The studies 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 7 of 26

demonstrate that dicamba is rapidly absorbed and translocated by grasses, grapes, black valentine 

beans, wheat and bluegrass, as well as in soybeans. Dicamba is metabolized in plants mainly by 

demethylation and hydroxylation. 

The registrant has developed a dicamba-tolerant cotton (known as MON88701), which contains a 

gene that expresses an enzyme to catalyze the breakdown of dicamba. This enzyme, O-demethylase, 

works by cleaving a specific carbon-oxygen bond converting the aromatic methoxyl group of 

dicamba into an aromatic hydroxyl group to form the non-herbicidal DSCA metabolite. DSCA is a 

known metabolite of dicamba found in soil, plants, and livestock. The petitioner has submitted a new 

metabolism study for dicamba-tolerant (MON 88701) cotton (48728701.der, P. Savoia, 03/25/2013). 

A summary of the characterization and identification of residues is shown in Appendix I along with 

the chemical names and structures of the identified metabolites illustrated in Appendix II. A 

summary of the data and findings follow. 

For this study, metabolism was found to occur at an appreciable rate with the first step in the process 

being demethylation of parent into the DCSA metabolite. Residue levels were considerably lower for 

the pre-emergence samples in comparison to those obtained following post-emergence treatment. 

Greater residue concentrations were obtained for the cotton leaves/stems (surrogate gin byproducts) 

as opposed to seed. These data indicate that residues tend to be on the surface of the dicamba-tolerant 

cotton plant. Parent dicamba was identified in all the matrices tested which include both gin 

byproducts and in seed at lower levels. Its metabolites DCSA glucoside, DCSA, and DCGA 

glucoside were found to be present in all matrices as well. The 5-OH dicamba metabolite was not 

identified in any matrix. For dicamba-tolerant cotton, DCSA glucoside was the major metabolite 

obtained with the highest levels being found in the gin byproducts samples. 

Based on these results, the petitioner proposes that the metabolism of dicamba in MON 88701 cotton 

proceeds by the demethylation of dicamba to form the DCSA metabolite. The formation of DCSA 

occurs through the action of the dicamba O-demethylase enzyme produced by the dicamba monooxygenase gene introduced into this variety of cotton for tolerating application of the herbicide. The 

petitioner notes that due to the predominance of the demethylation pathway, 5-OH dicamba is not 

observed as a metabolite found in either dicamba-tolerant cotton or soybean. 

In consultation with the HED Residues of Concern Knowledgebase Subcommittee (ROCKS) cochairs on March 18, 2013, the residues of concern (ROC) in dicamba-tolerant cotton were determined 

for both tolerance setting and risk assessment purposes. The newly submitted data supports including 

parent and the DCSA metabolite, as well as the 5-OH dicamba metabolite found in non-resistant 

varieties as the residues of concern in cotton for tolerance expression and risk assessment. 

The rationale for the ROC decision is as follows. Residues present in both cotton and dicambatolerant cotton were comprised of dicamba, and its metabolites, 5-OH dicamba, DCSA, and DCGA. 

While the DCGA metabolite was detected in field trial samples, and can be considered of comparable 

toxicity to the parent compound, the available analytical enforcement methodology is not considered 

validated for the DCGA metabolite. However, dicamba, 5-OH dicamba, and DCSA account for the 

majority of the residues in both tolerant and non-tolerant cotton and will provide sufficient residues 

with which to monitor for misuse for both tolerant and non-tolerant cotton; therefore, the ROC for 

tolerance setting purposes is dicamba, 5-OH dicamba, and DCSA.
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 8 of 26

For the purpose of risk assessment, HED considered both the exposure and hazard profiles for 

dicamba, 5-OH dicamba, DCSA, and DCGA and is including dicamba, 5-OH dicamba, and DCSA as 

the ROC for tolerant and non-tolerant cotton. Based on available toxicity studies and structural 

similarities, HED considers the parent and all three metabolites to be of comparable toxicity. While 

DCGA may be of comparable toxicity, it was present in the cotton metabolism studies at less than 

10% of the total radioactive residue (TRR), and is only detected in livestock feed items, not in human 

food items. Further, inclusion of this metabolite as a ROC in feed items would have no material 

impact on the livestock dietary burden since calculation of the reasonably balanced livestock diets are 

driven by other feed items with far higher residues. Thererfore, HED is not including the DCGA 

metabolite as an ROC for risk assessment. The residues of concern that were concluded for tolerance 

expression and risk assessment in crop commodities based on these data are presented below in Table 

4. 

Table 4. Dicamba Residues of Concern.

Matrix Tolerance Expression Residues for Risk Assessment

Barley, corn, grasses, oats, proso 

millet, sorghum, sugarcane, and 

wheat

Dicamba + 5-OH dicamba Dicamba + 5-OH dicamba

Asparagus Dicamba + DCSA1 Dicamba + DCSA

Cotton, Soybeans and aspirated 

grain fractions (AGFs)

Dicamba + 5-OH dicamba + DCSA Dicamba + 5-OH dicamba + DCSA

1

 DCSA also referred to as 3,6-dichloro-2-hydroxybenzoic acid or as 3,6-dichlorosalicylic acid.

 

860.1300 Nature of the Residue - Livestock

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

The nature of the residue in livestock is adequately understood based upon acceptable metabolism 

studies made on ruminants and poultry. The residues of concern in meat, milk poultry, and eggs are 

dicamba and its DCSA metabolite established under 40 CFR §180.227(a)(2). A new livestock 

commodity storage stability study and ruminant feeding study made at an increased dicamba parent 

feeding level of 1000 ppm was provided in support of reregistration. Both studies were determined to 

be adequate and no further livestock storage stability or ruminant feeding studies are required 

(D320564 & D322482, C. L. Olinger, 12/08/2005). 

860.1340 Residue Analytical Methods

Plant commodities

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

DER Reference: 48728702.der.docx (Residue Analytical Method for Dicamba-Tolerant Cotton)

Enforcement method: Adequate methods available for the enforcement of the newly proposed cotton 

seed and cotton gin byproducts tolerances. The Pesticide Analytical Manual (PAM) Vol. II lists 

Method I (AM 02658A) which uses GC/ECD analysis to carry out the determination of dicamba 

in/on crop commodities. The sensitivity of this method is listed to be 0.05 ppm and it has been 

validated by the Agency using corn and sorghum commodities. An improved plant enforcement 

method using GC/ECD analysis that includes an acid hydrolysis step for improved extraction 

efficiency has been developed as a modification to Method I. For this method, the reported limit of 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 9 of 26

quantitation (LOQ) is 0.02 ppm, and pending revisions suggested by the Agency, it will likewise be 

included in PAM Vol. II. 

Data collection methods: The cotton field trial samples analyzed in support of this petition were 

made using a validated Liquid Chromatography/Mass Spectrometer/Mass Spectrometer (LC/MS/MS) 

analytical method. Developed by Monsanto as method AG-ME-13801-01, it is entitled “Analytical 

Method for the Determination of Dicamba and its Major Metabolites in Cotton Matrices by 

LC/MS/MS”. For this method, samples are first extracted using a mixture of acetonitrile:water 

(40:60, v:v). An aliquot of the extract is then hydrolyzed with 1 N HCl at 95°C in an oven followed 

by partitioning with a mixture of ethyl acetate:isooctane (20:80), v:v). Water is then added to the 

organic phase and the sample is concentrated by evaporation until only the aqueous solution remains. 

The resulting samples are acidified and analyzed by LC/MS/MS determination. A complete 

description of the method and validation data determining dicamba along with its 5-OH dicamba, 

DSCA, and DCGA metabolites were included in this submission (MRID No. 48728702, P. Savoia, 

03/25/2013). The method determined residues of parent, 5-OH dicamba, and DCSA separately. The 

method limit of quantitation (LOQ) was 0.02 ppm determined for each analyte in cotton undelinted 

seed, meal, hulls, and alkali refined oil. The LOQ was 0.04 ppm for cotton gin byproducts. The 

method was validated using samples of the various cotton matrices fortified with each analyte at 0.02, 

0.20, and 10 ppm except for cotton gin byproducts which was fortified at 0.04, 0.40, and 10 ppm. 

Mean recoveries were within the acceptable range of 70% to 120% with the coefficient of variation 

less than 20% for each matrix tested to demonstrate the method is adequate for data collection. The 

tolerance is expressed as residues of dicamba and its metabolites expressed as dicamba; therefore, the 

residues of 5-OH dicamba, DCSA, and DCGA are converted to parent equivalents using molecular 

weight conversion factors of 0.933, 1.068, and 0.991, respectively.

Livestock commodities

The analysis of animal commodities is not relevant to this petition because no new livestock 

tolerances are being proposed for this action.

860.1360 Multiresidue Methods

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

Appendix II of PAM Volume I specifies that dicamba is completely recovered using Section 402 E2 

of Protocol B but is only partially recovered using Section 402 E1 of Protocol B. There are no

recovery data for MRM determining any of the dicamba metabolites of concern (5-OH dicamba and 

DCSA), and these data have been required. However, because single analyte methods for 

enforcement have thus been provided, the additional MRM data are not needed.

860.1380 Storage Stability

DER Reference: 48728704.der.docx (Stability of Dicamba Residues in Dicamba-Tolerant Cotton)

In support of this petition, Monsanto has submitted storage stability data for dicamba along with its 

DSCA and DCGA metabolites in/on MON 88701 cotton. Data on the stability of the 5-OH dicamba 

metabolite was not provided, and is not required since residues of that metabolite are not found in 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 10 of 26

cotton undelinted seed. The storage durations and conditions of the dicamba-tolerant (MON 88701)

cotton samples studied are presented below in Table 5. 

Table 5. Summary of Storage Conditions for Cotton Commodities.

Matrix 

(RAC or Extract)

Storage 

Temp. (°C)

Analyte Maximum 

Storage Duration 

(Days)

Interval of Demonstrated Storage Stability

Cotton, undelinted 

seed

Held below 

freezing at the 

field sites and 

at -20°C at the 

laboratory.

Dicamba 13-196 days (0.4-

6.4 months)

Residues of dicamba, DCGA, and DCSA are 

stable during freezer storage for up to 277 days (9 

months) in undelinted cotton seed (MRID No. 

48728704). 

The stability of 5-OH dicamba was not 

determined concurrently because it was not 

detected in cotton undelinted seed. 

5-OH Dicamba 13-122 days (0.4-

4.0 months)

DCGA 13-285 days (0.4-

9.4 months)

DCSA 13-121 days (0.4-

4.0 months)

Cotton, gin 

byproducts

Held below 

freezing at the 

field sites and 

at -20°C at the 

laboratory.

Dicamba 17-27 days (0.6-0.9 

months)

Storage stability data are not required since these

samples were analyzed within 30 days of harvest. 5-OH Dicamba

DCGA

DCSA

Cotton, hulls Ambient at 

field sites, -

12°C at 

processor, and

-20°C at 

laboratory.

Dicamba 33-40 days (1.1-1.3 

months)

Storage stability data are not required as these

processed fractions were generally analyzed 

5-OH Dicamba 33-34 days (1.1 within 30 days of processing.

months) DCGA

DCSA

Cotton, meal Ambient at 

field sites, -

12°C at 

processor, and

-20°C at 

laboratory.

Dicamba 26-27 days (0.9

months)

5-OH Dicamba

DCGA

DCSA

Cotton, alkali 

refined oil

Ambient at 

field sites, -

12°C at 

processor, and

-20°C at 

laboratory.

Dicamba 24-25 days (0.8

months) 5-OH Dicamba

DCGA

DCSA

Cotton, RBD1 oil Ambient at 

field sites, -

12°C at 

processor, and

-20°C at 

laboratory.

Dicamba 19-20 days (0.6-0.7 

5-OH Dicamba months)

DCGA

DCSA

1

 RBD – Refined Bleached Deodorized.

Conclusions. Adequate storage stability data for the residues of dicamba in/on dicamba-tolerant 

cotton commodities have been provided to support the studies provided in this submission. 

860.1400 Water, Fish, and Irrigated Crops

This guideline requirement is not relevant to the current action. 

860.1460 Food Handling

This guideline requirement is not relevant to the current action. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 11 of 26

860.1480 Meat, Milk, Poultry, and Eggs

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

For this action, a 70.0 ppm tolerance will be established for cotton gin byproducts which is a 

livestock feedstuff fed to beef cattle. The dicamba maximum theoretical dietary burdens to livestock 

were previously calculated in the residue chemistry considerations for the 2005 RED. While HED is 

recommending the establishment of a 70 ppm tolerance for cotton gin byproducts, roughage, a 

tolerance of 250 ppm on grass hay, another livestock roughage feed item, was already included in the 

maximum theoretical dietary burden calculation; therefore, the addition of this new livestock

tolerance will not materially impact the previously calculated dietary burden, as the calculation would 

default to the roughage with the highest impact, in theoretical dietary burden, but a maximum 

reasonably balanced dietary burden (MRBD) which considers reasonable diets for livestock, rather 

than assuming livestock consume any of the feed stuff with the highest residue in any quantity. If 

HED were to recalculate the MRBD burden for dicamba at this time, not only would the cotton gin 

byproducts be superseded by the grass hay, so not be materially included in the calculation, but it is 

also likely that the overall MRBD burden would be substantially reduced from that calculated 

maximum theoretically dietary burden from 2005. Tolerances in livestock commodities are based on 

that 2005 RED dietary burden, which is likely an overestimate of livestock exposure, and not 

impacted by this new feedstuff tolerance; therefore, no new animal tolerances are needed to support 

this new use on dicamba-tolerant cotton. 

860.1500 Crop Field Trials

DER Reference: 48728703.der1.docx (Magnitude of Dicamba Residues in Dicamba-Tolerant Cotton)

Monsanto has submitted crop field trial data for dicamba on dicamba-tolerant (MON 88701) cotton. 

Thirteen (13) field trials were conducted during the 2010 growing season in the representative North 

American Free Trade Agreement (NAFTA) Growing Zones. These studies were performed in 

NAFTA Growing Zones 2 (GA and SC; 2 trials), 4 (AR, LA, and MO; 3 trials), 6 (TX; 1 trial), 8 (OK 

and TX; 5 trials), and 10 (CA; 2 trials). Each trial site consisted of one untreated and three to four 

treated test plots. 

Each treated test plot received the maximum total seasonal application rate of 2.0-2.1 lb ae/A applied 

following one (1) of four (4) distinct use patterns evaluated for study. The first use pattern (TRT 1) 

was the cultivation of the control plot which received no application of the test substances. 

The second use pattern (TRT 2) was performed as three foliar broadcast applications applied at preemergence, the 6-leaf stage, and at 15-days past the 1st white flower. The third use pattern (TRT 3) 

was also made as three foliar broadcast applications applied at pre-emergence, 1st open boll, and 7-

days prior to harvest. The forth use pattern (TRTs 4 & 5) was done using four post-emergence foliar 

broadcast applications applied at the 6-leaf stage, 15-days past the 1st white flower, 1st open boll, and 

7-days prior to harvest. For this use pattern, TRT 4 was carried out using a 4.0 lb ae/gal SL 

diglycolamine salt product proposed for registration. TRT 5 was a bridging study made using a 5.0 lb 

ae/gal monoethanolamine salt formulation of dicamba for testing its equivalency to the diglycolamine 

salt product. A summary of the use patterns is provided below in Table 6.
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 12 of 26

Table 6. Summary of Field Trial Use Patterns for Treating Cotton with Dicamba.

TRT Number 

of Sites

EP Growth Stages/ Target Application Rates lb ae/A (kg ae/ha)

Pre-emergence 6 Leaf 1

st White Flower 

+ 15 days

First Open 

Boll

7 Days Prior 

to Harvest

1 13 -- -- -- -- -- --

2 13 4 lb ae/gal SL 1.0 (1.1) 0.50 (0.56) 0.50 (0.56) -- --

3 13 4 lb ae/gal SL 1.0 (1.1) -- -- 0.50 (0.56) 0.50 (0.56)

4 13 4 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)

5 4 5 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)

 

All treatments were made using ground equipment (backpack, hand-held or tractor-mounted sprayers) 

with a non-ionic surfactant and ammonium sulfate added to the spray mixture at spray volumes of 

18.8-21.6 gal/A. The use patterns evaluated for study followed the maximum labeled rate with preemergent applications all being made at 1.0 lb ae/A. The post-emergence treatments likewise 

followed the label using a maximum single in crop application rate of 0.5 lb ae/A made at a 7-day 

RTI and a 7-day PHI. The combined total of all applications appropriately followed the maximum 

labeled rate not exceeding 2.0 lb ae/A or 64 fluid ounces per acre in a given year. Additional samples 

were also collected from two trial sites for the TRT 2 and TRT 4 study use patterns to assess residue 

decline. 

To determine the magnitude of the residue, the cotton RACs were analyzed by LC/MS/MS analysis 

according to Monsanto Method AG-ME-1381-01. The reported LOQ for this LC/MS/MS method is 

0.02 ppm for each analyte in cotton undelinted seed and 0.04 ppm in gin byproducts. The method 

was successfully validated prior to and in conjunction with the analysis of the field trial samples. It is 

important to note that the analytical method does not specify protocol for conversion of metabolite 

residues to parent equivalents. The quantifiable residues of 5-OH dicamba, DCSA, and DCGA were 

converted to parent equivalents using molecular weight conversion factors of 0.933, 1.068, and 0.991, 

respectively.

The average residues for dicamba and the 5-OH dicamba and DCSA metabolites of concern for 

cotton undelineted seed ranged from <0.06-1.72 ppm. Cotton gin byproducts were also harvested as 

stripper cotton from 3 field trials following the TRT 2 use pattern, as well as from 3 additional trials 

from the TRT 4 use pattern. The number of samples provided for this RAC is adequate because the 

data from stripper only cotton for gin byproducts generally contains much more trash than picker 

cotton and is worst case. For the cotton gin byproducts samples that were analyzed, average residues 

for dicamba, and the 5-OH dicamba and DCSA metabolites of concern ranged from 0.53-29.6 ppm. 

These data examine the broad pattern of use offered by the label which shows that later postemergence treatments give much higher residues then those made at earlier growth stages. No 

residues of dicamba were appropriately observed above the reported LOQ of 0.02 ppm for cotton 

undelinted seed or 0.04 ppm in gin byproducts for any of the untreated control samples. The results 

of the residue decline studies performed for the TRT 2 use pattern yielded residues in cotton 

undelinted seed at or below the 0.02 ppm LOQ. Therefore, residue decline could not be assessed for 

these studies. For the residue decline studies following the TRT 4 use pattern, residues of dicamba 

were found to decrease in undelinted cotton seed with an increasing PHI. A summary of the residue 

data acquired in these studies are presented in Table 7. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 13 of 26

Table 7. Summary of Residue Data from Cotton Crop Field Trials with Dicamba.

Commodity Analyte Total App.

Rate

lb ae/A

(kg ae/ha)

PHI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. Dev.

TRT 2 (Applications at Preemergence, 6-leaf stage, and first white flower + 15 days; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

49-105 13 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

5-OH Dicamba 13 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

DCSA 13 <0.02 0.23 <0.02 0.23 0.02 0.04 0.06

Combined Residues 13 <0.06 <0.28 <0.06 <0.28 0.06 0.09 0.06

Gin 

byproducts

Dicamba 2.0

(2.2)

82-84 3 <0.04 <0.04 <0.04 <0.04 0.04 0.04 N/A

5-OH Dicamba 3 <0.04 <0.04 <0.04 <0.04 0.04 0.04 N/A

DCSA 3 0.39 1.73 0.43 1.58 0.67 0.89 0.61

Combined Residues 3 <0.47 <1.82 <0.53 <1.66 0.75 0.97 0.61

TRT 3 (Applications at Preemergence, first open boll stage, and 7 days prior to harvest; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

6-8 13 0.06 1.97 0.06 1.38 0.65 0.64 0.43

5-OH Dicamba 13 <0.02 0.02 <0.02 <0.02 0.02 0.02 N/A

DCSA 13 <0.02 0.25 <0.02 0.16 0.03 0.05 0.05

Combined Residues 13 <0.12 <2.24 <0.10 <1.56 0.71 0.71 0.48

TRT 4 (Applications at 6-leaf, first white flower + 15 days, first open boll, and 7 days prior to harvest; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0-2.1

(2.2-2.4)

6-8 13 0.09 1.54 0.12 1.42 0.47 0.61 0.41

5-OH Dicamba 13 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 N/A

DCSA 13 0.02 0.27 0.02 0.27 0.06 0.08 0.07

Combined Residues 13 <0.13 <1.83 <0.16 <1.72 0.56 0.71 0.48

TRT 4 (Applications at 6-leaf, first white flower + 15 days, first open boll, and 7 days prior to harvest; EP: Clarity)

Gin 

byproducts

Dicamba 2.0

(2.2)

6-7 3 3.09 23.6 3.13 23.0 14.9 13.7 10.0

5-OH Dicamba 3 <0.04 0.04 <0.04 <0.04 0.04 0.04 N/A

DCSA 3 1.70 6.29 1.78 6.17 4.50 4.15 2.22

Combined Residues 3 <4.83 29.9 <5.06 <29.6 19.7 18.1 12.2

TRT 5 (Applications at 6-leaf, first white flower + 15 days, first open boll, and 7 days prior to harvest; EP: MON 11968)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

7-8 4 0.17 0.72 0.20 0.62 0.41 0.41 0.23

5-OH Dicamba 4 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

DCSA 4 0.02 0.17 0.02 0.12 0.04 0.06 0.04

Combined Residues 4 <0.21 <0.91 <0.24 <0.76 0.47 0.49 0.27

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 (0.02 ppm each analyte in undelinted cotton seed and 0.04 ppm for each analyte in cotton gin byproducts) was used 

for any results reported as <LOQ in Table C.3. Combined residues of dicamba, 5-OH dicamba, DCGA, and DCSA are expressed in 

parent equivalents. Individual analyte results are reported as per se. N/A = Not applicable.

2

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

Conclusions. The submitted crop field trial results provided by Monsanto for MON 88701 cotton 

treated with dicamba are adequate to fulfill data requirements. The number and location of these field 

trials are sufficient in meeting the OCSPP 860.1500 Residue Chemistry Test Guidelines for 

determining the magnitude of the residue in/on cotton RACs. There were no unusual meteorological 

conditions during the course of the field trials which would adversely affect the quality and integrity 

of the study. An acceptable method was used for quantitation of residues in/on cotton RACs and 

adequate supporting storage stability data are available. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 14 of 26

860.1520 Processed Food and Feed

DER Reference: 48728703.der2.docx (Magnitude of Dicamba Residues in Dicamba-Tolerant Cotton)

Monsanto has submitted processing study data for dicamba-tolerant MON 88701 cotton treated with 

dicamba. Samples used for processing were generated from the two (2) trials held in Missouri and 

Texas during the 2010 growing season discussed above. Each trial site maintained two treated test 

plots which received the maximum total seasonal application rate of 2.0-2.1 lb ae/A applied following 

one (1) of two (2) distinct use patterns evaluated for study. 

All applications were made at the maximum labeled rate with the 4 lb ae/gal SL diglycolamine salt 

formulation of dicamba. Treatments were made using ground equipment at spray volumes of 19.7-

20.5 gal/A (184-192 l/ha) and included a nonionic surfactant (NIS) and ammonium sulfate (AMS) 

adjuvants. Samples of cotton undelinted seed were harvested using a mechanical picker at maturity 

which followed a PHI of 71-79 days for TRT 2 and 6-7 days for TRT 4. The resulting cotton 

undelinted seed samples were then processed into meal, hulls, alkali-refined oil, and RBD (Refined 

Bleached Deodorized) oil by GLP Technologies located in Navasota Texas using procedures 

simulating commercial processing.

To analyze for residues of dicamba, the cotton RAC and its processed commodities were determined 

using the Monsanto LC/MS/MS method AG-ME-1381-01. The reported LOQ for this LC/MS/MS 

method is 0.02 ppm for each analyte in cotton undelinted seed as well as for its processed 

commodities. The method was successfully validated prior to and in conjunction with the analysis of 

the field trial samples. As previously noted, this analytical method does not specify protocol for 

conversion of metabolite residues to parent equivalents. The quantifiable residues of 5-OH dicamba, 

DCSA, and DCGA were converted to parent equivalents using molecular weight conversion factors

of 0.933, 1.068, and 0.991, respectively.

For the two use patterns tested in this study, quantifiable residues were only obtained for the four 

post-emergence applications comprising TRT 4. Using these data, the concentration factors for each 

dicamba residue of concern was calculated for the processed commodities of dicamba-tolerant cotton 

seed. These data indicate that the combined residues of dicamba do not concentrate in hulls, meal, 

alkali refined oil, or RBD oil by yielding processing factors of ≤1.0x for each dicamba analyte, 

respectively. A summary of the data acquired from these processing studies is presented below in 

Table 8.
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 15 of 26

Table 8. Summary of Residue Data from the Cotton Processing Study made with Dicamba.

RAC: MRID No. Processed Commodity Total Rate

lb ae/A (Kg ae/A)

TRT1 Residues2(ppm) Avg. Processing Factor3

Parent 5-OH DCSA Parent 5-OH DCSA

Cotton/ MRID 

No. 48728703

Undelinted Seed (RAC) 2.0

(2.2)

4 0.65 <0.02 0.04 -- -- --

Hulls 0.43 <0.02 0.04 0.66x NC 1.0x

Meal <0.02 <0.02 <0.02 <0.03x NC <0.5x

Alkali Refined Oil <0.02 <0.02 <0.02 <0.03x NC <0.5x

RBD Oil <0.02 <0.02 <0.02 <0.03x NC <0.5x

1

 TRT – notes the use pattern that was followed for study. 

2

 Residues of dicamba include parent along with the 5-OH dicamba and DCSA metabolites of concern expressed in parent equivalents 

obtained for the TRT 4 use pattern trials. The LOQ is 0.02 ppm for each analyte in every given matrix. Concentrations found at or 

below the LOQ are denoted as < 0.02 ppm and included in the totals as 0.02 ppm. 

3

 NC – “not calculated” since there are not quantifiable residues in the RAC. 

Conclusions: The cotton processing study is adequate to satisfy OCSPP 860.1520 data requirements. 

Residues of dicamba do not concentrate in the processed commodities of dicamba-tolerant (MON 

88701) cotton. Therefore, separate tolerances are not required for the processed commodities of 

dicamba-tolerant (MON 88701) cotton. 

860.1650 Submittal of Analytical Reference Standards 

Analytical standards for dicamba and its metabolites of concern are currently available in the EPA 

National Pesticide Standards Repository (personal communication with Theresa Cole, BEAD, 

01/30/2013). The current stock of standards is set to expire on 11/30/2015. 

860.1850/860.1900 Confined and Field Accumulation in Rotational Crops

Reregistration Eligibility Decision Memo, D317699, 12/20/2005, C. L. Olinger

The December 2005 Reregistration Eligibility Decision (RED) for dicamba requires additional 

rotational crop studies in order to satisfy data requirements. However, these data are not needed if a 

120-day plantback interval is specified when dicamba is applied at the maximum seasonal rate of 

0.75 lb ae/A. For greater seasonal application rates of 0.75-2.0 lb ae/A, only crops with established 

tolerances can be rotated for planting. Because no new rotational crop data have been submitted, the 

plantback restrictions noted in the 2005 RED are required, and have been appropriately reflected on 

the proposed product label for dicamba-tolerant (MON 88701) cotton. 

860.1550 Proposed Tolerances

Permanent tolerances are established under 40 CFR §180.227(a)(1) for dicamba and its 3,6-dichloro5-hydroxybenzoic acid (5-OH dicamba) metabolite. There are also additional tolerances listed under 

40 CFR §180.227(a)(2) for dicamba and its 3,6-dichloro-2-hydroxybezoic acid metabolite, and under 

40 CFR §180.227(a)(3) for dicamba, and the 5-OH dicamba and DSCA metabolites. The tolerance 

expression recommended for cotton commodities based on the new metabolism data provided in 

support of this action is parent, 5-OH dicamba, and DSCA established under 40 CFR §180.227(a)(3). 

However, the 40 CFR §180.227(a)(1) citation for dicamba currently lists a 0.2 ppm tolerance for 

cotton, undelinted seed. This registration action supersedes the 40 CFR §180.227(a)(1) cotton 

undelinted seed tolerance which requires it to be removed from the federal register. Therefore all 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 16 of 26

tolerances for cotton RACs are now to be established under 40 CFR §180.227(a)(3) as recommended 

above. 

The International Residue Limit (IRL) summary is shown in Attachment 1 of this memorandum.

There are MRLs of 0.2 ppm in Mexico and 0.04 ppm established by Codex on cotton seed currently 

established. Mexico adopts existing U.S. crop tolerances for export purposes which in this instance is 

the current cotton undelinted seed tolerance of 0.2 ppm. There are currently no Mexican, Canadian or 

Codex MRLs established for cotton gin byproducts. Because the registrant is now requesting a late 

season use of dicamba on dicamba-tolerant cotton, the currently established international tolerances 

are not adequate to cover residues likely from the newly proposed use in the U.S. In addition, the 

dicamba residues of concern for dicamba-tolerant cotton also include the DCSA metabolite which is 

not found nor regulated in the other common varieties of cotton. Therefore, harmonization with 

respect to the tolerance expression is not possible at this time for cotton seed. Since there are no 

international tolerances on cotton gin byproducts, there is no issue of international harmonization 

relevant to that tolerance. 

The cotton field trial residue data reflecting late season treatments at the labeled 7-day PHI minimum 

(TRT 3 & TRT 4) were evaluated by the OECD calculation procedures to determine an appropriate 

tolerance level (see Appendix III) to yield a recommended tolerance of 3.0 ppm for cotton undelinted 

seed. Using the OECD calculation procedures, the cotton gin by products data reflecting late season 

treatments at the labeled 7-day PHI minimum (TRT 4) were also evaluated and a tolerance of 70.0

ppm is recommended (see Appendix III). As previously noted , no concentration in cotton seed 

processed commodities was seen; therefore, separate tolerances are not required for cotton processed 

commodities. The final tolerance recommendations are shown below in Table 9. 

Table 9. Tolerance Summary for Dicamba.

Commodity Established 

Tolerance 

(ppm)

Proposed 

Tolerance 

(ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity Definition

Tolerances Proposed for 40 CFR §180.227(a)(3)

Cotton, gin byproducts -- 70.0 70.0

Cotton, undelinted seed 0.2 3.0 3.0

 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 17 of 26

References

DP No.: D317699

Subject: Dicamba. Residue Chemistry Considerations for the Reregistration Eligibility 

Decision (RED) Document. Summary of Analytical Chemistry and Residue Data.

From: C. L. Olinger

To: K. Tyler

Date: 12/20/2005

MRIDs: None

DP No.: None

Subject: Dicamba Registration Standard

From: C. L. Trichilo

To: A. Rispin and R. Taylor

Date: 08/12/1983

MRIDs: None

DP No.: D320564 and D322842

Subject: Reregistration of Dicamba. Livestock Storage Stability Study and Ruminant Feeding 

Study

From: C. L. Olinger

To: K. Tyler

Date: 12/08/2005

MRIDs: 44891303 and 46668101

Attachments: 

International Residue Limit Status Sheet

Appendix I - Characterization and Identification of Radioactive Residues in Dicamba-Tolerant Cotton

Appendix II - Chemical Names and Structures of Dicamba and its Metabolites

Appendix III - Tolerance Assessment Calculations
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 18 of 26

International Residue Limits 

Dicamba (029801, 029802, 029806, 128931, 128944 & 129043; 01/16/2013)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition1:

US Canada Mexico2 Codex3

40 CFR 180.227:

Plant: Compliance with the tolerance 

levels is to be determined by measuring 

only the residues of dicamba, 3,6-

dichloro-0-anisic acid, and its 

metabolites, 3,6-dichloro-5-hydroxy-0-

anisic acid, and 3,6-dichloro-2-

hydroxybenzoic acid, calculated as the 

stoichiometric equivalent of dicamba

benzoic acid, 3,6-

dichloro-2-

methoxy-, 

including the 

metabolite benzoic 

acid, 2,5-dichloro3-hydroxy-6-

methoxyPlants: Dicamba

Animals:

sum of dicamba 

and 3,6-

dichlorosalicylic 

acid (DCSA) 

expressed as 

dicamba.

The residue is not 

fat-soluble.

Commodity4 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico2 Codex3

Cotton, undelinted seed 3

0.04 cotton seed 

(*)

Cotton, gin byproducts 70

Completed: M. Negussie; 01/17/2013

1 The U.S. Residue definition for cotton commodities now includes the DCSA metabolite not found nor regulated in the 

common varieties of cotton.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = processed 

postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the fat portion of the 

sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC.

4

Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and not 

those proposed by the applicant.
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 19 of 26

Appendix I – Characterization and Identification of Radioactive Residues in Dicamba-Tolerant 

Cotton

Appendix I. Summary of Characterization and Identification of Radioactive Residues in DicambaTolerant Cotton Matrices Following Application of [Phenyl-U14C]dicamba at 2.094 lb ae/A 

(preemergence) or 2.065 lb ae/A (postemergence)

Preemergence Postemergence

Seed Gin byproducts Seed Gin byproducts

TRR = 0.1621 ppm TRR = 0.8493 ppm TRR = 0.9778 ppm TRR = 60.024 ppm

% TRR ppm %TRR ppm %TRR ppm %TRR ppm

Dicamba 0.09 0.0001 0.50 0.004 0.85 0.008 4.48 2.691

DCSA glucoside 0.73 0.0012 27.77 0.236 3.42 0.033 16.83 10.101

DCSA 0.06 0.0001 5.42 0.046 1.91 0.019 13.39 8.035

DCGA glucoside 0.09 0.0001 0.68 0.006 1.1 0.011 2.46 1.476

MCTHBA glucoside -- -- -- -- -- -- 3.33 1.998

MCDHBA glucoside 

sulfate -- -- -- -- -- -- 4.71 2.828

MCDHBA glucoside -- -- -- -- -- -- 0.84 0.505

MCTHBA cyc. 

glucoside -- -- 2.94 0.025 -- -- 2.76 1.656

Dicamba amide -- -- 3.22 0.027 -- -- -- --

Fatty acids 16.05 0.026 -- -- 10.07 0.098 -- --

Glycerol 2.86 0.005 -- -- 1.35 0.013 -- --

Sugars/natural 

products 4.59 0.0074 8.94 0.076 5.61 0.055 2.69 1.613

Phosphate rinse 3.87 0.006 3.25 0.028 1.96 0.019 6.20 3.72

Starch 2.79 0.005 2.73 0.023 2.19 0.021 7.05 4.234

Protein 17.71 0.029 1.71 0.015 10.10 0.099 2.25 1.350

Pectin 7.40 0.012 1.91 0.016 4.04 0.039 2.66 1.595

Lignin 6.18 0.010 5.28 0.045 14.00 0.136 6.60 3.962

Cellulose 4.37 0.007 0.90 0.008 3.13 0.031 0.62 0.374

Hemicellulose 14.43 0.023 5.35 0.045 13.49 0.132 2.80 1.679

Acid Hydrolysates 5.07 0.008 -- -- 3.21 0.031 -- --

Unidentified (oil) 1.94 0.003 -- -- 0.84 0.008 -- --

Discrete unknowns 3.03 0.0049 15.96 0.136 5.36 0.052 0.86 0.518

Total identified 0.97 0.0015 40.53 0.344 7.28 0.071 48.80 29.29

Total characterized 90.29 0.1463 46.03 0.392 75.35 0.734 31.73 19.045

Total extractable 92.65 0.150 97.38 0.827 90.34 0.883 99.39 59.659

Unextractable (PES)1 7.35 0.012 2.62 0.022 9.66 0.094 0.61 0.365

Accountability2 100 100 100 100
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 20 of 26

Appendix II - Chemical Names and Structures of Dicamba and its Metabolites

Appendix II. Summary of Chemical Names and Structures of Dicamba and its Metabolites. 

Common name/code Chemical name Chemical structure

Dicamba 3,6-dichloro-2-methoxybenzoic acid

DCSA Glucoside 3,6-dichloro-2-(β-Dglucopyranosyloxy)benzoic acid

DCSA 3,6-dichloro-2-hydroxy benzoic acid

DCGA Glucoside 2,5-dichloro-3-(β-D-glucopyranosyloxy)-

6-hydroxybenzoic acid

MCTHBA Glucoside 2-Chloro-5,6-dihydroxy-3-(3,4,5-

trihydroxy-6-hydroxymethyltetrahydropyran-2-yloxy)benzoic acid

MCDHBA Glucoside Sulfate 6-Chloro-3-hydroxy-2-(3,4,5-trihydroxy6-sulfooxymethyltetrahydro-pyran-2-

yloxy)benzoic acid

MCDHBA Glucoside 6-Chloro-3-hydroxy-2-(3,4,5-trihydroxy6-hydroxymethyltetrahydro-pyran-2-

yloxy)benzoic acid
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 21 of 26

Appendix II. Summary of Chemical Names and Structures of Dicamba and its Metabolites. 

Common name/code Chemical name Chemical structure

MCTHBA Cyclic Glucoside 7-Chloro-3,4,6-trihydroxy-2-

hydroxymethyl-3,4,4a,9a-tetrahydro-2H1,9.10-trioxa-anthracene5-carboxylic acid

Dicamba Amide 3,6-dichloro-2-methoxybenzamide
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 22 of 26

Appendix III. Tolerance Assessment Calculations.

Cotton, undelinted seed

The dataset used to establish a tolerance for dicamba on cotton undelinted seed consisted of field trial

results held in the representative NAFTA Growing Zones during the 2010 growing season. It was 

acquired to evaluate the registration of dicamba for post-emergence use on dicamba-tolerant cotton 

since this variety can tolerate application of the herbicide in this manner. The data reflect the 

maximum seasonal application rate of 2.0 lb ae/A or 64 fluid ounces per acre in a given year 

following a 7-day RTI and a 7-day PHI. Treatments were made with a 4.0 lb ae/gal SL 

diglycolamine salt product which included a non-ionic surfactant and ammonium sulfate added to the 

spray mixture. These field trial data quantified the expected range of residues in cotton undelinted 

seed following treatment according to the proposed use pattern. All cotton undelinted seed samples 

had combined residues of dicamba above the LOQ of 0.02 ppm. 

To establish an appropriate tolerance level on this cotton RAC, only the data acquired using late 

season treatments at the labeled 7-day PHI minimum (TRT 3 & TRT 4) were entered into the 

Organization for Economic Cooperation and Development (OECD) calculation procedures for 

determination. For those field trials where sampling replicates were taken, the average or mean value 

was used for calculation. The mean residue values used to calculate the resulting tolerance level is

provided in the table below. When using the OECD calculation procedures, the resulting MRL value 

is always found to be greater than or equal to the highest residue within the dataset. MRLs are 

displayed without decimal zeros after the last significant figure and are rounded in the last step of 

calculation to produce a result in the region of the 95th percentile. The MRL estimate calculated at 

the “CF x 3 Mean” level gives a value of 3.0 ppm for the combined residues of dicamba. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 23 of 26

Dicamba

Cotton, undilented seed

U.S.

PHI= 6-8 days

Total number of data (n) 26

Percentage of censored data 0%

Number of non-censored data 26

Lowest residue 0.110

Highest residue 1.720

Median residue 0.700

Mean 0.726

Standard deviation (SD) 0.458

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 1.720

- Mean + 4 SD 2.560

- CF x 3 Mean 2.178

Unrounded MRL 2.560

Rounded MRL 3

Residues (mg/kg) n

0.11 1

0.16 1

0.17 1

0.19 1

0.23 1

0.26 1

0.36 1

0.38 1

0.43 1

0.46 1

0.52 2

0.68 1

0.72 1

0.75 1

0.8 1

0.92 1
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 24 of 26

1 1

1.05 1

1.07 1

1.09 1

1.11 1

1.26 1

1.35 1

1.57 1

1.72 1
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 25 of 26

Cotton, gin byproducts

The dataset used to establish a tolerance for dicamba on cotton gin byproducts consisted of field trial 

results held in the representative NAFTA Growing Zones during the 2010 growing season. It was 

acquired to evaluate the registration of dicamba for post-emergence use on dicamba-tolerant cotton 

since this variety can tolerate application of the herbicide in this manner. The data reflect the 

maximum seasonal application rate of 2.0 lb ae/A or 64 fluid ounces per acre in a given year 

following a 7-day RTI and a 7-day PHI. Treatments were made with a 4.0 lb ae/gal SL 

diglycolamine salt product which included a non-ionic surfactant and ammonium sulfate added to the 

spray mixture. These field trial data quantified the expected range of residues in cotton gin

byproducts following treatment according to the proposed use pattern. All cotton gin byproducts 

samples had combined residues of dicamba above the LOQ of 0.04 ppm. 

To establish an appropriate tolerance level on this cotton RAC, only the data acquired using late 

season treatments at the labeled 7-day PHI minimum (TRT 4) were entered into the Organization for 

Economic Cooperation and Development (OECD) calculation procedures for determination. For 

those field trials where sampling replicates were taken, the average or mean value was used for 

calculation. The mean residue values used to calculate the resulting tolerance level is provided in the 

table below. When using the OECD calculation procedures, the resulting MRL value is always found 

to be greater than or equal to the highest residue within the dataset. MRLs are displayed without 

decimal zeros after the last significant figure and are rounded in the last step of calculation to produce 

a result in the region of the 95th percentile. The MRL estimate calculated at the “CF x 3 Mean” level 

gives a value of 70.0 ppm for the combined residues of dicamba. 
Dicamba Summary of Analytical Chemistry and Residue Data DP No. D408384

Page 26 of 26

Dicamba

Cotton, gin byproducts

U.S.

PHI= 6-8 days

Total number of data (n) 3

Percentage of censored data 0%

Number of non-censored data 3

Lowest residue 5.060

Highest residue 29.600

Median residue 19.700

Mean 18.120

Standard deviation (SD) 12.346

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 29.600

- Mean + 4 SD 67.504

- CF x 3 Mean 54.360

Unrounded MRL 67.504

Rounded MRL 70

High uncertainty of MRL estimate.

[Small dataset]

Residues (mg/kg) n

5.06 1

19.7 1

29.6 1
Dicamba/ MON 11900/PC Code 128931/Monsanto Company 

DACO 6.3/0PPTS 860.1300/0ECD 11 6.2.2, 6.2.3 & II IA 8.2, 8.4.1 , 8.4.2 

Nature of the Residues in Plants - Dicamba-Tolerant Cotton (Event MON 8870 I) 

Primary Evaluator Date: 11/ 15/2012 

Versar, Inc. 

- ' Approved by rJ-1-rK .La__,,~ Date: 04/22/2013 

Peter Savoia, Chemist, OCSPP-HED-RAB YNII 

Note: This Data Evaluaiion Record (DER) was originally prepared under contract by Vcrsar. Inc. (6850 Vasar Center. 

Springfield. VA 2215 1: submitted I I / 15/20 12). The DER has been reviewed b) HED and revised to rencct current Office of 

Pesticide Programs (OPP) policies. 

STUDY REPORT: 

48728701 Whitehead, T.; Mierkowski, M.: Chott, R. (2011) Amended Report for MSL0021858: 

Metabolism of (Carbon 14)-Dicarnba in Dicamba-Tolerant Corton. Project Number: 

MSL0023760/0CR, REG/09/046, 1901 W. Unpublished study prepared by Monsanto Company. 

378 p. 

EXECUTIVE SUMMARY: 

Monsanto has submitted a study investigating the metabolism of uniformly ring-labeled (phenylU-14C]dicamba (specific activity of9.85-9.91 mCi/mmol) in dicamba- and glufosinate-tolerant 

cotton, identified as Event MON 88701 (formerly GH_S26695). Event MON 88701 cotton 

expresses a modifi ed dicamba mono-oxygenase (OMO) gene derived from Stenotrophomonas 

maltophilia and the bialaphos resistance (BAR) gene isolated from Streptomyces hygroscopicus. 

The expression of DMO confers dicamba tolerance, and the expression of BAR confers 

glufosinate tolerance. The radiolabeled test substance was formulated as an aqueous solution of 

the diglycolamine (DGA) salt and applied to cotton grown in outdoor box plots. One plot 

received a single pre-emergence soil application (PRE-T) at 2.094 lb ae/ A on the day of planting 

after seed was planted, and the other plot received a single post-emergence foliar application 

(POE-T) at 2.065 lb ae/ A at the first white flower stage (76 days after planting). Samples of seed 

cotton and leaves/stems (surTOgate gin byproducts) were collected at maturity: 180 days after 

treatment (DAT) for the PRE-T plot and I 04 DAT for the POE-T plot. The in-life phase of the 

study was conducted by PTRL West, Inc. (J lercules, CA) and Excel Research Services (Fresno, 

CA), and the analytical phase of the study was conducted by Monsanto (St. Louis, MO). 

Total radioactive residues (TRR) were determined by combustion/LSC. Following a single preemergence soil application of [ 14C]dicamba at 2.094 lb ae/A. TRR were 0.1621 ppm in seed and 

0.8493 ppm in gin byproducts harvested at a 180-day pre-harvest interval (PHI). Following a 

single post-emergence foliar application at 2.065 lb ae/A, TRR were 0.9778 ppm in seed and 

60.0235 ppm in gin byproducts harvested at a I 04-day PHI. 

Extraction with hexane released 18.91 % and 11.47% TRR from PRE-T and POE-T seed, 

respectively; extraction with acetonitrile (ACN) and ACN/water together released an additional 

11.91 % and 26.78% TRR, respectively. In gin byproducts, extraction with ACN/water released 

the majority of the radioactivity: 76.25% and 71.21% TRR from PRE-T and POE-T gin 

byproducts, respectively. Remaining non-extractable residues for all matrices were subjected to 

0408384/MRID No. 48728701 Page I of24 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 2 of 24

sequential enzymatic and chemical hydrolysis and oxidation procedures, including a phosphate 

rinse followed by hydrolysis with α-amylase and protease; EDTA extraction; oxidation with 

chlorite; hydrolysis with cellulase, 24% aqueous KOH, and sulfuric acid (seed only); a second 

hydrolysis with protease (POE-T seed only); and hot DMSO extraction (POE-T seed only). 

These procedures released 52.12-61.82% TRR in seed and 21.13-28.18% TRR in gin 

byproducts. Non-extractable residues remaining following hydrolysis procedures were 7.35% 

TRR (0.012 ppm) in PRE-T seed, 9.66% TRR (0.094 ppm) in POE-T seed, 2.62% TRR (0.022 

ppm) in PRE-T gin byproducts, and 0.61% TRR (0.365 ppm) in POE-T gin byproducts. These 

procedures adequately extracted the majority of residues (90.3-99.4%) from all cotton matrices. 

Extraction results were normalized; therefore, accountabilities were ~100%.

Up to 38 peaks were observed in the initial metabolic profiles of seed and gin byproducts. All 

metabolite peaks accounting for ≥2% TRR were isolated and purified by preparative high 

performance liquid chromatography (HPLC) for further investigation. After isolation, residues 

were identified by HPLC/UV and by mass spectral analysis including LC/MS and LC/MS/MS; 

Gas chromatography/electron ionization mass spectrometry (GC/EI/MS) was used for volatile 

derivatives of the metabolites or their hydrolysis products. Isolated metabolites were subjected 

to partitioning with ethyl acetate, acid, base or enzymatic hydrolysis, and/or chemical 

derivatizations (methylation and acetylation) to provide additional structural information. 

Comparison of the chromatographic and mass spectral properties of the metabolite derivatives or 

hydrolysates to those of synthetic reference standards was used to confirm the identities of the 

metabolites. The study is supported by adequate storage stability data.

Parent dicamba was identified in all matrices at low levels: 0.09-0.85% TRR (0.0001-0.008 

ppm) in seed and 0.50-4.48% TRR (0.004-2.691 ppm) in gin byproducts. Metabolites DCSA 

glucoside, DCSA, and DCGA glucoside were also present in all matrices. DCSA glucoside was 

the major identified metabolite in gin byproducts, at 16.83-27.77% TRR (0.236-10.101 ppm) and 

was present in seed at low levels (0.73-3.42% TRR). Free DCSA was the next most abundant 

metabolite in POE-T gin byproducts (13.39% TRR, 8.035 ppm) and was present in PRE-T gin 

byproducts at 5.42% TRR and in seed at 0.06-1.91%TRR. DCGA glucoside was identified at 

low levels in all matrices (0.09-2.46% TRR). The remaining identified metabolites were found 

in gin byproducts only and accounted for ≤4.71% TRR each, including MCTHBA glucoside, 

MCDHBA glucoside sulfate, and MCDHBA glucoside in POE-T gin byproducts, MCTHBA 

cyclic glucoside in both PRE-T and POE-T gin byproducts, and dicamba amide in PRE-T gin 

byproducts only. Because dicamba amide was only observed in PRE-T plants, it is believed to 

be a soil metabolite that was taken up by the plants. 

Remaining extractable radioactivity in cotton seed and gin byproducts was characterized as 

triglycerides and sugars/natural products. In the hexane extracts of seed, triglycerides including 

fatty acids (palmitic, stearic, linoleic, and oleic) accounted for 10.07-16.05% TRR (0.026-0.098 

ppm), while glycerol accounted for 1.35-2.86% TRR. In the ACN/water extracts of all matrices, 

sugars/natural products (Peak 1) accounted for 2.69-8.94% TRR (0.0074-1.613 ppm). This peak 

was characterized extensively, indicating that it was a mixture of polar materials, including

sugars such as glucose, sucrose, and raffinose, and amino acids such as phenylalanine and 

glutamic acid. Unidentified components in oil accounted for 0.84-1.94% TRR in seed; discrete 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 3 of 24

unknowns in the ACN/water extracts together accounted for 0.86-15.96% TRR (0.0049-0.518 

ppm) in seed and gin byproducts, with none present at >2.91% TRR. 

Radioactivity in non-extractable residues was characterized by sequential enzymatic and 

chemical hydrolysis/oxidation. In seed, these procedures indicated that the majority of 

radioactivity was incorporated into hemicellulose (13.49-14.43% TRR, 0.023-0.132 ppm), 

protein (10.10-17.71% TRR, 0.029-0.099 ppm), and lignin (6.18-14.0% TRR, 0.01-0.136 ppm). 

Other fractions (including starch, pectin, and cellulose) individually accounted for ≤7.4% TRR. 

In gin byproducts, radioactivity was incorporated primarily into starch (2.73-7.05% TRR, 0.023-

4.234 ppm), lignin (5.28-6.60% TRR, 0.045-3.962 ppm), and hemicellulose (2.80-5.35% TRR,

0.045-1.679 ppm). Other fractions (including protein, pectin, and cellulose) individually 

accounted for ≤6.2% TRR. 

Based on the results of the metabolism study on dicamba-tolerant cotton, the petitioner proposes 

that the metabolism of dicamba proceeds by initial demethylation of dicamba to form DCSA 

through the action of the dicamba O-demethylase enzyme, which is the product of the DMO 

gene introduced to confer dicamba tolerance. The petitioner noted that, due to the predominance 

of the O-demethylation pathway, 5-OH-dicamba is not observed as a metabolite in dicambatolerant cotton or soybean. While free DCSA was observed in cotton matrices (POE-T and PRET gin byproducts in particular), the majority of DCSA is found as its conjugate DCSA glucoside. 

Some DCSA glucoside is further modified by hydroxyl replacement of chlorine to form 

MCDHBA glucoside which is then further conjugated by sulfation to form MCDHBA glucoside 

sulfate. In a minor pathway, DCSA is hydroxylated at the 5-position, presumably by a P-450 

enzyme or other oxygenase, to form DCGA. DCGA is not observed as a free metabolite in 

cotton matrices but is converted to DCGA glucoside in which the glucose moiety is attached to 

the hydroxyl group at the 5-position of DCGA (based upon comparison to the same metabolite 

identified in dicamba-tolerant soybean). DCGA glucoside is further converted to MCTHBA 

glucoside by hydroxyl replacement of chlorine at the 3-position. Alternatively, MCTHBA cyclic 

glucoside may form from DCGA glucoside through displacement of chlorine at the 6-position of 

the DCGA portion of the molecule by a hydroxyl group of the glucose moiety. Dicamba amide

was a minor metabolite that was only observed in PRE-T matrices. The petitioner concluded that 

this metabolite is most likely the result of the metabolic conversion of the carboxylic acid moiety 

of dicamba to an amide functional moiety via soil microbial metabolism.

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, the plant metabolism data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document D408384.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. No deviations from regulatory requirements were reported which 

would have an impact on the validity of the study.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 4 of 24

A. BACKGROUND INFORMATION

Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a selective benzoic acid herbicide registered 

for the control of weeds prior to their emergence. The dicamba Reregistration Eligibility 

Decision (RED) was issued December 2005. The chemical structure and nomenclature of 

dicamba and its metabolites 5-OH dicamba, DSCA, and DCGA are presented in Table A.1. The 

physicochemical properties of the technical grade of dicamba acid are presented in Table A.2. 

TABLE A.1. Test Compound Nomenclature.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Not applicable.

Compound

Common name 5-Hydroxy-dicamba

Company experimental name 5-OH dicamba

IUPAC/CAS name 2,5-dichloro-3-hydroxy-6-methoxybenzoic acid

CAS registry number 7600-50-2

Compound

Common name DCSA; 3,6-dichlorosalicylic acid

Company experimental name MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 5 of 24

TABLE A.1. Test Compound Nomenclature.

Compound

Common name DCGA; 3,6-dichlorogentistic acid

Company experimental name MON 52724

IUPAC/CAS name 2,5-dichloro-3,6-dihydroxybenzoic acid

CAS registry number 18688-01-2

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED, DP# 317699, 

12/20/05, C. Olinger pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)

B. EXPERIMENTAL DESIGN

B.1. Test Site and Crop Information

The in-life and analytical phases of the study were conducted by PTRL West, Inc. (Hercules, 

CA) and Excel Research Services (Fresno, CA). Cotton was grown from seed planted in loamy

sand soil in outdoor box plots. Separate boxes were used for pre- and post-emergence 

applications. The plots were located in Madera, CA. 

Crops were maintained under normal agricultural conditions. Fertilizer was applied during the 

study period; however, maintenance pesticides were not applied. Weather data for the site was 

provided, including minimum/maximum temperatures and daily rainfall. Weather conditions 

were reported to be normal for the study duration. When rain threatened, the plots were covered 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 6 of 24

so that no rain fell on the plots. Plots were watered by hand as needed. Soil characteristics are 

presented in Table B.1.1, and crop information is presented in Table B.1.2.

TABLE B.1.1. Test Site Information.

Type Method Soil characteristics

Type %OM pH CEC

meq/100g

Preemergence soil 

treatment (PRE-T)

Cotton was grown from seed in a 4 ft. x 4 

ft. (16 ft2; PRE-T) or 3 ft. x 3 ft. (9 ft2; 

POE-T) wooden box filled with ~18 in of 

soil and lined with heavy- gauge plastic. 

Loamy sand 0.2 6.8 6.3

Postemergence foliar 

treatment (POE-T)

TABLE B.1.2. Crop Information.

Crop/crop group Variety1 Growth stage at application Growth stage at 

harvest

Harvested

Matrix

Cotton; Oilseed group 

20

Event MON 

88701 

PRE-T: day of planting after planting

seed

Maturity Seed; leaves and stems 

(gin byproducts)

POE-T: first white flower stage (50% 

of the plants had first white flower)

1 Dicamba- and glufosinate-tolerant cotton was used in the study, identified as Event MON 88701 (formerly GH_S26695). Event 

MON 88701 cotton expresses a modified dicamba mono-oxygenase (DMO) gene derived from Stenotrophomonas maltophilia 

and the bialaphos resistance (BAR) gene isolated from Streptomyces hygroscopicus. The expression of DMO confers dicamba 

tolerance, and the expression of BAR confers glufosinate tolerance to MON 88701

B.2. Test Materials

The radiolabeled test substance, [phenyl-U14C]dicamba (specific activity 45.0 mCi/mmol, 7.53 

mBq/mg), was dissolved in ACN and isotopically diluted with unlabeled dicamba. The 

characteristics of the test substance are presented in Table B.2.1.

TABLE B.2.1. Test Material Characteristics.

Preemergence Treatment Postemergence Treatment

Chemical structure

Radiolabel position [Phenyl-U14C]dicamba

Lot No. 2344-2 2344-9

Purity 98.4% prior to and after application 98.0% prior to application; 98.1% after application

Specific activity 9.91 mCi/mmol (99548 dpm/μg or 1.66 MBq/mg) 9.85 mCi/mmol (98946 dpm/μg, 1.65 MBq/mg)

B.3. Study Use Pattern

The isotopically diluted test substance was formulated as an aqueous solution of the DGA salt

and diluted with water. Applications were made using a hand-held sprayer. Applications were 

made as a single pre-emergence soil broadcast application (PRE-T) at 2.094 lb ae/A on the day 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 7 of 24

of planting after seed was planted or as a single post-emergence foliar application (POE-T) at

2.065 lb ae/A 76 days after planting, when >50% of the plants had reached the first white flower 

growth stage. Samples of seed and leaves/stems were harvested at PHIs of 180 days for the 

PRE-T plot and 104 days for the POE-T plot. The study use pattern is summarized in Table 

B.3.1.

TABLE B.3.1. Use Pattern Information.

Chemical name [Phenyl-U14C]dicamba

Application method The test material was formulated as an aqueous solution of the DGA salt, diluted with water, and 

applied as a single preemergence soil application (PRE-T plot) or a single postemergence foliar 

application (POE-T plot).

Application rate PRE-T: 2.094 lb ae/A (2,347 g ae/ha)

POE-T: 2.065 lb ae/A (2,315 g ae/ha)

Number of applications PRE-T: 1

POE-T: 1

Timing of application PRE-T: Single preemergence soil application made on the day of planting after seed was planted

POE-T: Single postemergence application made at the first white flower stage (76 days after 

planting).

PHI PRE-T: 180 days

POE-T: 104 days

B.4. Identification/ Characterization of Residues

B.4.1. Sample Handling and Preparation

Samples of seed and leaves/stems (gin byproducts) were harvested 180 days after application for 

the PRE-T plot and 104 days after application for the POE-T plot. The seed cotton was ginned 

and delinted using a small-scale gin at Excel Research Services, Inc. prior to shipment to the 

analytical laboratory (Monsanto Environmental Services Technology Center, St. Louis, MO). 

The leaves and stems were shipped to PTRL West (Hercules, CA), where they were processed 

by grinding in a food processer in the presence of dry ice prior to shipment to the analytical 

laboratory. At the laboratory, the undelinted seed was further processed by cryogenic milling

using a SPEX CertiPrep Freezer/Mill; no further processing was required for the gin byproducts 

samples. All samples were stored frozen at Monsanto (<-20 °C) prior to and after processing 

when not in use. 

Cotton seed samples were extracted three times with hexane followed by a single ACN

extraction to remove oils, after which they were extracted four times with ACN:water (40:60; 

v/v). Cotton gin byproducts were extracted four times with ACN:water (40:60; v/v). Following 

centrifugation, the ACN/water extracts of each matrix were combined and rotary evaporated to 

remove the ACN and part of the water. Evaporation was stopped at near dryness for gin 

byproducts, while seed extracts were not evaporated to dryness because of issues caused by 

insoluble materials. All samples were re-dissolved in water containing 0.5% formic acid and 

ACN (92:8, v:v) and reserved for HPLC analysis. 

Separate subsamples of PRE-T and POE-T seed were also subjected to exhaustive hexane 

extraction for analysis of fatty acids. The samples were extracted with hexane (3x), and the 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 8 of 24

hexane extracts were combined and evaporated to near dryness. Methanol and concentrated 

sulfuric acid were added, and the samples were refluxed for 2.5 hours, then cooled and 

partitioned with hexane (3x). The combined extracts were evaporated to near dryness and 

reconstituted in hexane for analysis by HPLC. 

The non-extractable residues remaining following ACN/water extraction of seed and gin 

byproducts were subjected to the following sequential enzymatic and chemical 

hydrolysis/oxidation procedures; mixtures were centrifuged or filtered after each step. 

Both seed and gin trash:

1) Phosphate rinse (in 0.05 M phosphate buffer, pH 7.0, at RT, for 20 min.)

2) α-Amylase hydrolysis for starch (in 0.05 M phosphate buffer, pH 7.0, at 30 °C for 20 hr.)

3) Protease hydrolysis for protein (in TRIS buffer, pH 7.0, at 30 °C for 19 hr.)

4) EDTA extraction for pectin (with 0.05 M EDTA:0.05 M sodium acetate buffer, pH 5.0, at 

80 °C for 5 hr., then at RT overnight)

5) Chlorite oxidation for lignin (in glacial acetic acid containing sodium chlorite at 70 °C 

for 1 hr., then repeated with water, acetic acid, and sodium chlorite)

6) Cellulase hydrolysis for cellulose (in 0.05 M sodium acetate buffer, pH 5.0, at 37 °C for 

20 hr.)

7) 24% KOH hydrolysis for hemicellulose (from 37 to 24 °C for several hours, then at 24 °C

overnight)

Seed only:

8) Concentrated sulfuric acid (at RT, overnight)

9) Protease hydrolysis (POE-T seed; in 0.05 M TRIS buffer, pH 7.0, at 30 °C for 23 hr.)

10) Hot DMSO extraction (POE-T seed; heated to 78 °C over 1.5 hr., at RT for 17 hr., heated 

to 70 °C over several hr., at RT for 2 hr., heated to 77 °C over 2.5 hr., cooled to RT)

Partitioning with ethyl acetate was used to investigate organic/aqueous partitioning behavior of 

dicamba residues and to facilitate quantitation of the metabolites or to facilitate isolation and 

purification of metabolites. The combined ACN/water extracts of seed and gin byproducts were 

rotary evaporated to remove ACN, and the remaining aqueous solution was acidified to pH 1-2 

with concentrated HCl and partitioned three times with ethyl acetate. The ethyl acetate phase 

was evaporated to dryness, and the residue was reconstituted in 0.5% aqueous formic acid and 

acetonitrile for HPLC analysis. The hydrolysates resulting from protease hydrolysis of PRE-T 

seed and 24% KOH hydrolysis of PRE-T and POE-T seed were acidified to pH <2 with 

concentrated HCl, then partitioned three times with ethyl acetate. For each digest, the combined 

ethyl acetate extracts and the remaining aqueous layer were aliquoted for LSC analysis. 

Quantitative results for the partitioning procedures are not included herein.

B.4.2. Analytical Methodology

TRR were determined by combustion/LSC. Radioactivity in extracts was determined by direct 

LSC, and radioactivity in non-extractable fractions was determined by combustion/LSC. The 

limit of quantitation for TRR determinations was not reported.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 9 of 24

Seed and gin byproducts extracts were subjected to HPLC/UV analysis for quantitation and 

generation of the metabolite profile. The HPLC systems were equipped with various columns, a 

UV detector (280, 254, or 210 nm), and a radioactive flow detector. Two methods were 

employed for detection and quantitation of radioactivity: HPLC with radioactive flow detection

(HPLC/RAD) in which the effluent from the UV detector was pumped through the flow detector 

to a detection cell for an analytical scale or semi-preparative scale HPLC column, and HPLC 

with fraction collection and LSC detection (HPLC/LSC), in which fractions were collected at 

0.3-min. intervals. HPLC Method B (C-18 column, gradient mobile phase of 0.5% formic acid 

and ACN) using HPLC/RAD and HPLC/LSC was the primary method used for residue 

quantitation and for generation of the metabolite profile. 

Up to 38 metabolite peaks were observed in cotton seed and gin byproducts. All metabolite 

peaks accounting for ≥2% TRR were isolated and purified by preparative HPLC for further 

investigation. Metabolites were isolated by preparative HPLC fractionation using HPLC method 

(Method B). The isolated metabolite fractions were typically purified by preparative 

fractionation using HPLC Method D (phenyl column, gradient mobile phase of 0.5% formic acid 

and ACN). HPLC Method C (C18 column, gradient mobile phase of 0.5% formic acid and 

methanol) was used to further separate isolated metabolites from matrix contaminants. 

The primary technique for identification of metabolites was mass spectral analysis which 

provided molecular weights and some structural information. LC/MS or LC/MS/MS with 

electrospray ionization (ESI) was conducted using an ion trap mass spectrometer interfaced with 

an Agilent 1200 RRLC system and HPLC methods M (C18 column, gradient mobile phase of 

0.1% formic acid and methanol), N and O (phenyl column, gradient mobile phase of 0.1% 

formic acid and ACN), P (amino column, isocratic mobile phase of 0.03% NH4OH and ACN), 

and Q (amino column, isocratic mobile phase of water and ACN). Typically, negative ion MS

was utilized for the metabolites and their hydrolysis products, and positive ion MS was utilized 

for neutral derivatives of the metabolites and for the two amides (dicamba amide and DCSA 

amide). GC/EI/MS conducted in the positive ion mode was utilized for volatile derivatives of 

the metabolites or their derivatives or hydrolysis products.

HPLC co-chromatography and/or retention time comparisons, as well as comparison of the 

chromatographic and mass spectral properties of the metabolite derivatives or hydrolysates to 

those of synthetic reference standards was used to confirm the identities of the metabolites. The 

chemical names and structures of the reference standards used in the study are presented in 

Appendix I. 

For the purpose of identification, metabolite peaks were isolated primarily from the POE-T gin 

byproducts; metabolites were not specifically isolated from the seed due to low residue levels

(with the exceptions of Peaks 19, 34, and 36 from POE-T seed). It was assumed that metabolite 

peaks in the seed extracts represent the same metabolite peaks in the gin byproducts with the 

same or similar retention times. To confirm the identity of the peaks in seed, the PRE-T seed 

extract was co-injected with a mixture of standards corresponding to metabolites identified in 

POE-T and PRE-T gin byproducts, and the retention times were compared and analyzed by 

HPLC/RAD using Method B.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 10 of 24

Prior to analysis by HPLC or mass spectrometry methods, isolated metabolites were 

characterized using a variety of methods alone or in combination to provide additional structural 

information, including:

 Partitioning with ethyl acetate (see above)

 Acid hydrolysis (to effect removal of sugar moieties) with 2 N HCl (at 95-100 °C for 1-2 

hr.) or 1 N HCl at (60 °C for 4 hr.)

 Base hydrolysis with 2 N NaOH (at 60 °C for 4 hr.)

 Methylation (for detection of carboxylic acid and/or phenolic groups) with 

trimethylsilyldiazomethane at RT for 35 min.

 Acetylation (for detection of hydroxyl or phenolic groups) with acetic anhydride (at RT 

for 1-2 hr. or overnight)

Identification of the metabolites DCGA glucoside (Peak 6) and DCSA glucoside (Peak 19) were 

achieved by LC/MS and/or HPLC/RAD comparisons with the same metabolites isolated from

soy forage from a metabolism study on dicamba-tolerant soybean (Report No. MSL0022659; no 

MRID found).

Metabolite Peak 1 (found in all matrices) was isolated from ACN/water extracts HPLC Method 

B. Peak 1 was also isolated from POE-T seed extracts using C18 solid phase extraction and 

sequential elution with water, ACN, and ethyl acetate. Peak 1 was also characterized by a 

number of procedures including: partitioning with ethyl acetate at acidic and neutral pH (<1.5 

and 6); acid hydrolysis followed by HPLC; HPLC using Method J (amino column and isocratic 

mobile phase of 0.03% NH4OH in water and ACN) to isolate possible saccharides and amino 

acids; and HPLC (PRE-T seed) using Method R (amino column, gradient mobile phase of water 

and ACN) to resolve component peaks in the organic phase following ethyl acetate partitioning. 

The Peak 1 radioactive components were also analyzed by negative ion electrospray LC/MS 

using HPLC Method Q and were compared to representative mono-, di- and tri-saccharide 

reference standards and amino acids. Confirmation of the identities of the mono and 

disaccharides observed in the LC/MS analyses was achieved by derivatization and GC/EI/MS 

analyses.

For identification of triglycerides, including fatty acids and glycerol in the hexane extracts of 

seed, the hexane phase following acidic methanolysis was analyzed by HPLC Method I (silverimpregnated strong cation exchange column, isocratic mobile phase of 1% ACN in hexane and 

hexanes). The peaks observed were consistent with those of the fatty acid methyl ester reference 

standards of stearic, oleic, and linoleic acid. Radioactivity remaining in the methanol fraction 

was designated glycerol. 

C. RESULTS AND DISCUSSION

The sample storage conditions and durations for dicamba-tolerant cotton matrices are presented 

in Table C.1.1. TRR determinations were completed within 10 days of harvest. The petitioner 

stated that initial HPLC analyses were conducted for POE-T seed and gin trash extracts within 

30 days of sample receipt to establish baseline profiles. Based on the dates of sample collection 

(10/28/09) and the experimental completion date (2/18/11, storage stability study), final analysis 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 11 of 24

of all samples was conducted within 478 days (15.7 months) of sample collection. To 

demonstrate storage stability, extracts of PRE-T and POE-T seed and gin byproducts were 

analyzed at the beginning of the study (47-99 days after collection), at a midway point (296-308 

days after collection) and again at 475-478 days after collection (POE-T samples only). The 

extractability of radioactivity was similar at all time intervals (Table C.1.2), and comparison of 

the metabolite profiles for the POE-T seed and gin byproduct samples following initial and final 

analysis indicated only negligible changes in distribution of residues. These data are sufficient to 

support the sample storage conditions and intervals from the submitted study.

TRR in dicamba-resistant matrices are reported in Table C.2.1. TRR were determined by 

combustion/LSC. Following a single pre-emergence soil application of [14C]dicamba at 2.094 lb 

ae/A, TRR were 0.1621 ppm in seed and 0.8493 ppm in gin byproducts harvested at a 180-day 

PHI. Following a single post-emergence foliar application at 2.065 lb ae/A, TRR were 0.9778 

ppm in seed and 60.0235 ppm in gin byproducts harvested at a 104-day PHI. 

The distribution of radioactivity in dicamba-tolerant cotton matrices is presented in Table C.2.2. 

Extraction with hexane released 18.91% and 11.47% TRR from PRE-T and POE-T seed, 

respectively; extraction with acetonitrile (ACN) and ACN/water together released an additional 

11.91% and 26.78% TRR, respectively. In gin byproducts, extraction with ACN/water released 

the majority of the radioactivity: 76.25% and 71.21% TRR from PRE-T and POE-T gin 

byproducts, respectively. Remaining non-extractable residues for all matrices were subjected to 

sequential enzymatic and chemical hydrolysis and oxidation procedures, including a phosphate 

rinse followed by hydrolysis with α-amylase and protease; EDTA extraction; oxidation with 

chlorite; hydrolysis with cellulase, 24% aqueous KOH, and sulfuric acid (seed only); a second 

hydrolysis with protease (POE-T seed only); and hot DMSO extraction (POE-T seed only). 

These procedures released 52.12-61.82% TRR in seed and 21.13-28.18% TRR in gin 

byproducts. Non-extractable residues remaining following hydrolysis procedures were 7.35% 

TRR (0.012 ppm) in PRE-T seed, 9.66% TRR (0.094 ppm) in POE-T seed, 2.62% TRR (0.022 

ppm) in PRE-T gin byproducts, and 0.61% TRR (0.365 ppm) in POE-T gin byproducts. These 

procedures adequately extracted the majority of residues (90.3-99.4%) from all cotton matrices. 

Extraction results were normalized; therefore, accountabilities were ~100%.

Up to 38 peaks were observed in the initial HPLC/UV profiles of seed and gin byproducts. All 

metabolite peaks accounting for ≥2% TRR were isolated and purified by preparative HPLC for 

further investigation. After isolation, residues were identified by HPLC/UV and by mass 

spectral analysis including LC/MS and LC/MS/MS; GC/EI/MS was used for volatile derivatives 

of the metabolites or their hydrolysis products. Isolated metabolites were subjected to 

partitioning with ethyl acetate, acid, base or enzymatic hydrolysis, and/or chemical 

derivatizations (methylation and acetylation) to provide additional structural information. 

Comparison of the chromatographic and mass spectral properties of the metabolite derivatives or 

hydrolysates to those of synthetic reference standards was used to confirm the identities of the 

metabolites.

The characterization and identification of residues in dicamba-tolerant cotton matrices are 

summarized in Table C.2.3. The parent, dicamba, was identified in all matrices at low levels: 
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 12 of 24

0.09-0.85% TRR (0.0001-0.008 ppm) in seed and 0.50-4.48% TRR (0.004-2.691 ppm) in gin 

byproducts. Metabolites DCSA glucoside, DCSA, and DCGA glucoside were also present in all 

matrices. DCSA glucoside was the major identified metabolite in gin byproducts, at 16.83-

27.77% TRR (0.236-10.101 ppm) and was present in seed at low levels (0.73-3.42% TRR). Free 

DCSA was the next most abundant metabolite in POE-T gin byproducts (13.39% TRR, 8.035

ppm) and was present in PRE-T gin byproducts at 5.42% TRR and in seed at 0.06-1.91%TRR. 

DCGA glucoside was identified at low levels in all matrices (0.09-2.46% TRR). The remaining 

identified metabolites were found in gin byproducts only and accounted for ≤4.71% TRR each, 

including MCTHBA glucoside, MCDHBA glucoside sulfate, and MCDHBA glucoside in POET gin byproducts, MCTHBA cyclic glucoside in both PRE-T and POE-T gin byproducts, and 

dicamba amide in PRE-T gin byproducts only. Because dicamba amide was only observed in 

PRE-T plants, it is believed to be a soil metabolite that was taken up by the plants.

Remaining extractable radioactivity in cotton seed and gin byproducts was characterized as 

triglycerides and sugars/natural products. In the hexane extracts of seed, triglycerides including 

fatty acids (palmitic, stearic, linoleic, and oleic) accounted for 10.07-16.05% TRR (0.026-0.098 

ppm), while glycerol accounted for 1.35-2.86% TRR. In the ACN/water extracts of all matrices, 

sugars/natural products (Peak 1) accounted for 2.69-8.94% TRR (0.0074-1.613 ppm). This peak 

was characterized extensively, indicating that it was a mixture of polar materials, including

sugars such as glucose, sucrose, and raffinose, and amino acids such as phenylalanine and 

glutamic acid. These sugars and amino acids are likely produced from extensive metabolism of 

dicamba to small molecules which are incorporated into natural plant constituents (such as 

carbohydrate, protein and oil) through normal plant metabolic processes. Unidentified 

components in oil accounted for 0.84-1.94% TRR in cotton seed; discrete unknowns in the 

ACN/water extracts together accounted for 0.86-15.96% TRR (0.0049-0.518 ppm) in seed and 

gin byproducts, with none present at >2.91% TRR. 

Radioactivity in non-extractable residues was characterized by sequential enzymatic and 

chemical hydrolysis/oxidation. In seed, these procedures indicated that the majority of 

radioactivity was incorporated into hemicellulose (13.49-14.43% TRR, 0.023-0.132 ppm), 

protein (10.10-17.71% TRR, 0.029-0.099 ppm), and lignin (6.18-14.0% TRR, 0.01-0.136 ppm). 

Partitioning of the hemicellulose and protein fractions with ethyl acetate following acidification 

resulted in low levels of radioactivity in the organic phase, indicating that the residues are polar 

in nature and unlikely to be related to dicamba metabolites. Other fractions (including starch, 

pectin, and cellulose) individually accounted for ≤7.4% TRR. In gin byproducts, radioactivity 

was incorporated primarily into starch (2.73-7.05% TRR, 0.023-4.234 ppm), lignin (5.28-6.60% 

TRR, 0.045-3.962 ppm), and hemicellulose (2.80-5.35% TRR, 0.045-1.679 ppm). Other 

fractions (including protein, pectin, and cellulose) individually accounted for ≤6.2% TRR. The 

conclusion from these analyses is that the metabolism of dicamba to small organic molecules 

results in the incorporation of the label into endogenous plant components (e.g., proteins, sugars, 

lignin, etc.) through normal metabolic processes.

The following peaks were designated unidentified following characterization/identification 

attempts; however, the petitioner provided the following tentative identifications:

 Peak 5: a highly conjugated dicamba-related compound
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 13 of 24

 Peak 9: conjugate of DCSA amide (Peak 27)

 Peak 14: conjugate of DCSA amide (Peak 27), or 3-chloro-2,6-dihydroxybenzoic acid 

 Peak 27: primary amide of DCSA (DCSA amide)

 Peak 32: conjugate of DCSA

C.1. Storage Stability

TRR determinations were completed within 10 days of harvest. The petitioner stated that initial 

HPLC analyses were conducted for POE-T seed and gin trash extracts within 30 days of sample

receipt to establish baseline profiles. Based on the dates of sample collection (10/28/09) and the 

experimental completion date (2/18/11, storage stability study), final analysis of all samples was 

conducted within 478 days (15.7 months) of sample collection. To demonstrate storage stability, 

extracts of PRE-T and POE-T seed and gin byproducts were analyzed at the beginning of the 

study (47-99 days after collection), at a midway point (296-308 days after collection) and again 

at 475-478 days after collection (POE-T samples only). The extractability of radioactivity was

similar at all time intervals (Table C.1.2), and comparison of the metabolite profiles for the POET seed and gin byproduct samples following initial and final analysis indicated only negligible 

changes in distribution of residues. These data are sufficient to support the sample storage 

conditions and intervals from the submitted study.

TABLE C.1.1. Summary of Storage Conditions

Matrix Storage Temperature

(°C)

Actual Study Duration1Interval of Demonstrated Storage 

Stability

Seed <-20 47 days 478 days (15.7 months)

Gin byproducts 79-99 days 475 days (15.6 months)

1 Interval between harvest and initial analysis of extracts by HPLC.

TABLE C.1.2. Comparison of Extraction Results Obtained at the Beginning, Middle, and End of the 

Analytical phase.

Matrix Normalized Extractability (%)

Initial (47-79 days) Mid (296-308 days) Final (475-478 days)

PRE-T Seed 27.42 30.84 Not analyzed

PRE-T Gin byproducts 73.57 76.24

POE-T Seed 35.07 38.26 40.37

POE-T Gin byproducts 67.76 71.28 69.10

1 Interval between harvest and initial analysis of extracts by HPLC.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 14 of 24

C.2. Identification, Characterization, and Distribution of Residues

TABLE C.2.1. Total Radioactive Residues (TRR) in Dicamba-Tolerant Cotton Matrices.

Matrix Timing and Applic. No. PHI

(days)

Residues (ppm [14C]dicamba)

Seed Gin byproducts

Dicamba-tolerant 

cotton

Single pre-emergence:

2.094 lb ae/A (2,347 g ae/ha)

180 0.1621 0.8493

Single post-emergence:

2.065 lb ae/A (2,315 g ae/ha)

104 0.9778 60.0235

TABLE C.2.2. Distribution of the Parent and the Metabolites in Dicamba-Tolerant Cotton Matrices 

Following Application of [Phenyl-U14C]dicamba at 2.094 lb ae/A (pre-emergence) or 2.065 

lb ae/A (post-emergence).

1

Metabolite Fraction Preemergence Postemergence

Seed Gin byproducts Seed Gin byproducts

TRR = 0.1621 ppm TRR = 0.8493 ppm TRR = 0.9778 ppm TRR = 60.024 ppm

% TRR ppm %TRR ppm %TRR ppm %TRR ppm

Hexane [initial extracts]2 20.25 0.0328 11.51 0.113

Triglycerides 14.41 0.0230 8.80 0.086

Unidentified 5.84 0.0098 2.71 0.027

Hexane [acidic methanolysis]

3 18.91 0.031 11.47 0.112

Hexane: Fatty acids

4 16.05 0.026 10.07 0.098

Acidic MeOH: Glycerol 2.86 0.005 1.35 0.013

Unidentified (oil) 1.94 0.003 0.84 0.008

ACN 0.44 0.001 0.48 0.005

ACN/water 11.47 0.019 76.25 0.648 26.30 0.257 71.21 42.744

Combined ACN, ACN/water5 11.91 0.020 26.78 0.262

Dicamba 0.09 0.0001 0.50 0.004 0.85 0.008 4.48 2.691

DCSA glucoside 0.73 0.0012 27.77 0.236 3.42 0.033 16.83 10.101

DCSA 0.06 0.0001 5.42 0.046 1.91 0.019 13.39 8.035

DCGA glucoside 0.09 0.0001 0.68 0.006 1.10 0.011 2.46 1.476

MCTHBA glucoside -- -- -- -- -- -- 3.33 1.998

MCDHBA glucoside 

sulfate

-- -- -- -- -- -- 4.71 2.828

MCDHBA glucoside -- -- -- -- -- -- 0.84 0.505

MCTHBA cyc. glucoside -- -- 2.94 0.025 -- -- 2.76 1.656

Dicamba amide -- -- 3.22 0.027 -- -- -- --

Sugars/natural products 4.59 0.0074 8.94 0.076 5.61 0.055 2.69 1.613

Discrete unknowns6 3.03 0.0049 15.96 0.136 5.36 0.052 0.86 0.518

Nonextractable 69.16 0.112 23.76 0.202 61.74 0.604 28.72 17.239

Phosphate rinse 3.87 0.006 3.25 0.028 1.96 0.019 6.20 3.72

α-Amylase (starch) 2.79 0.005 2.73 0.023 2.19 0.021 7.05 4.234

Protease (protein) 17.71 0.029 1.71 0.015 7.43 0.073 2.25 1.350

EDTA extract (pectin) 7.40 0.012 1.91 0.016 4.04 0.039 2.66 1.595

Chlorite (lignin) 6.18 0.010 5.28 0.045 8.43 0.082 6.60 3.962

Cellulase (cellulose) 4.37 0.007 0.90 0.008 3.13 0.031 0.62 0.374

24% KOH (hemicellulose) 14.43 0.023 5.35 0.045 13.49 0.132 2.80 1.679
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 15 of 24

TABLE C.2.2. Distribution of the Parent and the Metabolites in Dicamba-Tolerant Cotton Matrices 

Following Application of [Phenyl-U14C]dicamba at 2.094 lb ae/A (pre-emergence) or 2.065 

lb ae/A (post-emergence).

1

Metabolite Fraction Preemergence Postemergence

Seed Gin byproducts Seed Gin byproducts

TRR = 0.1621 ppm TRR = 0.8493 ppm TRR = 0.9778 ppm TRR = 60.024 ppm

% TRR ppm %TRR ppm %TRR ppm %TRR ppm

Sulfuric acid 5.07 0.008 3.21 0.031

Protease (second protein) 2.67 0.026

Hot DMSO (second lignin) 5.57 0.054

Nonextractable 7.35 0.012 2.62 0.022 9.66 0.094 0.61 0.365

1

 Extraction results were normalized for the original extraction procedures and for characterization of nonextractable residues 

(See Tables 14 and 15). Shading indicates that the extraction step and/or characterization analysis was not conducted for the 

matrix in question.

2

 Results as reported in Tables 9 and 11.

3 Calculated by the study reviewer to show distribution of triglycerides as fatty acids and glycerol, based on normalized values 

reported in Table 13.

4

 Including palmitic, stearic, oleic, and linoleic acids

5

 Calculated by the study reviewer by summing.

6 Unknowns (discrete quantitated peaks) are comprised of 19 components in PRE-T seed (each ≤0.45% TRR, ≤0.0007 ppm); 12 

components in POE-T seed (each ≤0.81% TRR, ≤0.008 ppm); 11 components in PRE-T gin byproducts (each ≤2.91% TRR, 

≤0.025 ppm); and 1 component in POE-T gin byproducts (0.86% TRR, 0.518 ppm).

TABLE C.2.3. Summary of Characterization and Identification of Radioactive Residues in DicambaTolerant Cotton Matrices Following Application of [Phenyl-U14C]dicamba at 2.094 lb ae/A 

(pre-emergence) or 2.065 lb ae/A (post-emergence)

Preemergence Postemergence

Seed Gin byproducts Seed Gin byproducts

TRR = 0.1621 ppm TRR = 0.8493 ppm TRR = 0.9778 ppm TRR = 60.024 ppm

% TRR ppm %TRR ppm %TRR ppm %TRR ppm

Dicamba 0.09 0.0001 0.50 0.004 0.85 0.008 4.48 2.691

DCSA glucoside 0.73 0.0012 27.77 0.236 3.42 0.033 16.83 10.101

DCSA 0.06 0.0001 5.42 0.046 1.91 0.019 13.39 8.035

DCGA glucoside 0.09 0.0001 0.68 0.006 1.1 0.011 2.46 1.476

MCTHBA glucoside -- -- -- -- -- -- 3.33 1.998

MCDHBA glucoside 

sulfate -- -- -- -- -- -- 4.71 2.828

MCDHBA glucoside -- -- -- -- -- -- 0.84 0.505

MCTHBA cyc. 

glucoside -- -- 2.94 0.025 -- -- 2.76 1.656

Dicamba amide -- -- 3.22 0.027 -- -- -- --

Fatty acids 16.05 0.026 -- -- 10.07 0.098 -- --

Glycerol 2.86 0.005 -- -- 1.35 0.013 -- --

Sugars/natural 

products 4.59 0.0074 8.94 0.076 5.61 0.055 2.69 1.613

Phosphate rinse 3.87 0.006 3.25 0.028 1.96 0.019 6.20 3.72

Starch 2.79 0.005 2.73 0.023 2.19 0.021 7.05 4.234

Protein 17.71 0.029 1.71 0.015 10.10 0.099 2.25 1.350

Pectin 7.40 0.012 1.91 0.016 4.04 0.039 2.66 1.595
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 16 of 24

TABLE C.2.3. Summary of Characterization and Identification of Radioactive Residues in DicambaTolerant Cotton Matrices Following Application of [Phenyl-U14C]dicamba at 2.094 lb ae/A 

(pre-emergence) or 2.065 lb ae/A (post-emergence)

Preemergence Postemergence

Seed Gin byproducts Seed Gin byproducts

TRR = 0.1621 ppm TRR = 0.8493 ppm TRR = 0.9778 ppm TRR = 60.024 ppm

% TRR ppm %TRR ppm %TRR ppm %TRR ppm

Lignin 6.18 0.010 5.28 0.045 14.00 0.136 6.60 3.962

Cellulose 4.37 0.007 0.90 0.008 3.13 0.031 0.62 0.374

Hemicellulose 14.43 0.023 5.35 0.045 13.49 0.132 2.80 1.679

Acid Hydrolysates 5.07 0.008 -- -- 3.21 0.031 -- --

Unidentified (oil) 1.94 0.003 -- -- 0.84 0.008 -- --

Discrete unknowns 3.03 0.0049 15.96 0.136 5.36 0.052 0.86 0.518

Total identified 0.97 0.0015 40.53 0.344 7.28 0.071 48.80 29.29

Total characterized 90.29 0.1463 46.03 0.392 75.35 0.734 31.73 19.045

Total extractable 92.65 0.150 97.38 0.827 90.34 0.883 99.39 59.659

Unextractable (PES)1 7.35 0.012 2.62 0.022 9.66 0.094 0.61 0.365

Accountability2 100 100 100 100

1

 Residues remaining after exhaustive extractions.

2

 Accountability = (Total extractable + Total unextractable)/(TRR from combustion analysis; see TABLE C.2.1) * 100. 

C.3. Proposed Metabolic Profile

Based on the results of the metabolism study on dicamba-tolerant cotton, the petitioner proposes 

that the metabolism of dicamba proceeds by initial demethylation of dicamba to form DCSA 

through the action of the dicamba O-demethylase enzyme, which is the product of the DMO 

gene introduced to confer dicamba tolerance. The petitioner noted that, due to the predominance 

of the O-demethylation pathway, 5-OH-dicamba is not observed as a metabolite in dicambatolerant cotton or soybean. While free DCSA was observed in cotton matrices (POE-T and PRET gin byproducts in particular), the majority of DCSA is found as its conjugate DCSA glucoside. 

Some DCSA glucoside is further modified by hydroxyl replacement of chlorine to form 

MCDHBA glucoside which is then further conjugated by sulfation to form MCDHBA glucoside

sulfate. In a minor pathway, DCSA is hydroxylated at the 5-position, presumably by a P-450 

enzyme or other oxygenase, to form DCGA. DCGA is not observed as a free metabolite in 

cotton matrices but is converted to DCGA glucoside in which the glucose moiety is attached to 

the hydroxyl group at the 5-position of DCGA (based upon comparison to the same metabolite 

identified in dicamba-tolerant soybean). DCGA glucoside is further converted to MCTHBA 

glucoside by hydroxyl replacement of chlorine at the 3-position. Alternatively, MCTHBA cyclic 

glucoside may form from DCGA glucoside through displacement of chlorine at the 6-position of 

the DCGA portion of the molecule by a hydroxyl group of the glucose moiety. Dicamba amide 

was a minor metabolite that was only observed in PRE-T matrices. The petitioner concluded that 

this metabolite is most likely the result of the metabolic conversion of the carboxylic acid moiety 

of dicamba to an amide functional moiety via soil microbial metabolism.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 17 of 24

The proposed metabolic pathway is depicted in Figure C.3.1, which was copied without 

alteration from MRID 48728701.

FIGURE C.3.1. Proposed Metabolic Profile of Dicamba in Dicamba-Tolerant Cotton

TABLE C.3.1. Identification of Compounds from Metabolism Study

Common name/code Chemical name Chemical structure

Dicamba

(Peak 36)

3,6-dichloro-2-methoxybenzoic acid

DCSA Glucoside

(Peak 19)

3,6-dichloro-2-(β-Dglucopyranosyloxy)benzoic acid
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 18 of 24

TABLE C.3.1. Identification of Compounds from Metabolism Study

Common name/code Chemical name Chemical structure

DCSA

(Peak 34)

3,6-dichloro-2-hydroxy benzoic acid

DCGA Glucoside

(Peak 6)

2,5-dichloro-3-(β-D-glucopyranosyloxy)-

6-hydroxybenzoic acid

MCTHBA Glucoside

(Peak 12)

2-Chloro-5,6-dihydroxy-3-(3,4,5-

trihydroxy-6-hydroxymethyltetrahydropyran-2-yloxy)benzoic acid

MCDHBA Glucoside Sulfate

(Peak 16)

6-Chloro-3-hydroxy-2-(3,4,5-trihydroxy6-sulfooxymethyltetrahydro-pyran-2-

yloxy)benzoic acid

MCDHBA Glucoside

(Peak 18)

6-Chloro-3-hydroxy-2-(3,4,5-trihydroxy6-hydroxymethyltetrahydro-pyran-2-

yloxy)benzoic acid

MCTHBA Cyclic Glucoside

(Peak 21)

7-Chloro-3,4,6-trihydroxy-2-

hydroxymethyl-3,4,4a,9a-tetrahydro-2H1,9.10-trioxa-anthracene5-carboxylic acid
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 19 of 24

TABLE C.3.1. Identification of Compounds from Metabolism Study

Common name/code Chemical name Chemical structure

Dicamba Amide

(Peak 29)

3,6-dichloro-2-methoxybenzamide

D. CONCLUSION

The results of the metabolism study adequately delineate the nature of the residue in dicambatolerant cotton treated with dicamba. Following a single pre-emergence soil application of 

[

14C]dicamba at 2.094 lb ae/A, TRR were 0.1621 ppm in seed and 0.8493 ppm in gin byproducts 

harvested at a 180-day PHI. Following a single post-emergence foliar application at 2.065 lb 

ae/A, TRR were 0.9778 ppm in seed and 60.0235 ppm in gin byproducts harvested at a 104-day 

PHI. 

The parent, dicamba, was identified in all matrices at low levels: 0.09-0.85% TRR in seed and 

0.50-4.48% TRR in gin byproducts. Metabolites DCSA glucoside, DCSA, and DCGA glucoside 

were also present in all matrices. DCSA glucoside was the major identified metabolite in gin 

byproducts, at 16.83-27.77% TRR and was present in seed at low levels (0.73-3.42% TRR). 

Free DCSA was the next most abundant metabolite in POE-T gin byproducts (13.39% TRR) and 

was present in PRE-T gin byproducts at 5.42% TRR and in seed at 0.06-1.91%TRR. DCGA 

glucoside was identified at low levels in all matrices (0.09-2.46% TRR). The remaining 

identified metabolites were found in gin byproducts only and accounted for ≤4.71% TRR each, 

including MCTHBA glucoside, MCDHBA glucoside sulfate, and MCDHBA glucoside in POET gin byproducts, MCTHBA cyclic glucoside in both PRE-T and POE-T gin byproducts, and 

dicamba amide in PRE-T gin byproducts only. Because dicamba amide was only observed in 

PRE-T plants, it is believed to be a soil metabolite that was taken up by the plants.

Remaining extractable radioactivity in seed and gin byproducts was characterized as 

triglycerides and sugars/natural products. In the hexane extracts of seed, triglycerides including 

fatty acids (palmitic, stearic, linoleic, and oleic) accounted for 10.07-16.05% TRR, while 

glycerol accounted for 1.35-2.86% TRR. In the ACN/water extracts of all matrices, 

sugars/natural products (Peak 1) accounted for 2.69-8.94% TRR. Unidentified components in oil 

accounted for 0.84-1.94% TRR in seed; discrete unknowns in the ACN/water extracts together 

accounted for 0.86-15.96% TRR in seed and gin byproducts, with none present at >2.91% TRR. 

Radioactivity in non-extractable residues was characterized by sequential enzymatic and 

chemical hydrolysis/oxidation. In seed, these procedures indicated that the majority of 

radioactivity was incorporated into hemicellulose (13.49-14.43% TRR), protein (10.10-17.71% 

TRR), and lignin (6.18-14.0% TRR). Other fractions (including starch, pectin, and cellulose) 

individually accounted for ≤7.4% TRR. In gin byproducts, radioactivity was incorporated 

primarily into starch (2.73-7.05% TRR), lignin (5.28-6.60% TRR), and hemicellulose (2.80-
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 20 of 24

5.35% TRR). Other fractions (including protein, pectin, and cellulose) individually accounted 

for ≤6.2% TRR. 

Based on the results of the metabolism study on dicamba-tolerant cotton, the petitioner proposes 

that the metabolism of dicamba proceeds by initial demethylation of dicamba to form DCSA 

through the action of the dicamba O-demethylase enzyme, which is the product of the DMO 

gene introduced to confer dicamba tolerance. The petitioner noted that, due to the predominance 

of the O-demethylation pathway, 5-OH-dicamba is not observed as a metabolite in dicambatolerant cotton or soybean. While free DCSA was observed in cotton matrices (POE-T and PRET gin byproducts in particular), the majority of DCSA is found as its conjugate DCSA glucoside. 

Some DCSA glucoside is further modified by hydroxyl replacement of chlorine to form 

MCDHBA glucoside which is then further conjugated by sulfation to form MCDHBA glucoside 

sulfate. In a minor pathway, DCSA is hydroxylated at the 5-position, presumably by a P-450 

enzyme or other oxygenase, to form DCGA. DCGA is not observed as a free metabolite in 

cotton matrices but is converted to DCGA glucoside in which the glucose moiety is attached to 

the hydroxyl group at the 5-position of DCGA (based upon comparison to the same metabolite 

identified in dicamba-tolerant soybean). DCGA glucoside is further converted to MCTHBA 

glucoside by hydroxyl replacement of chlorine at the 3-position. Alternatively, MCTHBA cyclic 

glucoside may form from DCGA glucoside through displacement of chlorine at the 6-position of 

the DCGA portion of the molecule by a hydroxyl group of the glucose moiety. Dicamba amide 

was a minor metabolite that was only observed in PRE-T matrices. The petitioner concluded that 

this metabolite is most likely the result of the metabolic conversion of the carboxylic acid moiety 

of dicamba to an amide functional moiety via soil microbial metabolism.

E. REFERENCES

None.

F. DOCUMENT TRACKING

Petition Number(s): 2F8067

DP Barcode(s): 408384

PC Code: 029801, 029802, 029806, 128931, 128944, & 129043

Template Version June 2005.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 21 of 24

APPENDIX I. Chemical Names and Structures of Reference Standards Used in Cotton Metabolism Study.
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 22 of 24

APPENDIX I. Chemical Names and Structures of Reference Standards Used in Cotton Metabolism Study 

(cont.).
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 23 of 24

APPENDIX I. Chemical Names and Structures of Reference Standards Used in Cotton Metabolism Study 

(cont.).
Dicamba/ MON 11900/PC Code 128931/Monsanto Company

DACO 6.3/OPPTS 860.1300/OECD II 6.2.2, 6.2.3 & IIIA 8.2, 8.4.1, 8.4.2

Nature of the Residues in Plants – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728701 Page 24 of 24

APPENDIX I. Chemical Names and Structures of Reference Standards Used in Cotton Metabolism Study 

(cont.).
:-:..d I Dicacmoba/MON 1 1900/PC Co

1

de I 28S93

8

1

6

r

0

Mons

0

a

1

n

0

to Ccompany 

2 5 4 2 6 

d 

4 

,, 

"·"· ... . DA 7.2.1 , 7.2.2, and 7.2.3 OPPT .134 E D llA 4 .. , .. an . .J 

Residue Analytical Method - Cotton 

Primary Evaluator 

Versar. Inc. 

,? 

Approved by ("~~1 ~ A'~~~ Pete1:-Savoia, Chemist, OCSPP-HED-RAB VNII 

Date: 11/15/2012 

Date: 04/22/20 13 

Note: This Data Evaluation Record (DER) was originally prepared under contract by Versar. Inc. (6850 Vcrsar Center. 

Springfield. VA 22151: submiucd 11 11 511 2). The DER has been reviewed by llED and revised to n:ncct current Office of 

Pesticide Programs (OPP) policies. 

STUDY REPORTS: 

48728702 Foster, J.; Mierkowski, M.; Miller. M. (2011) Amended Report for MSL0023267: 

Analytical Method for the Decermination of Dicamba and its Major Metabolites in Cotton 

Matrices by LC/MS/MS. Project Number: AG/ME/ 1381101/0CR, MSL0023759. Unpublished 

study prepared by Monsanto Company. 93p. 

EXECUTIVE SUMMARY: 

Monsanto has submitted an analytical method description and validation data for a data 

collection method, AG-ME-138 1-01, for the determination of residues of dicamba and its 

metabolites, 5-hydroxydicamba (5-0H dicamba), 3,6-dichlorosalicylic acid (OCSA) and 3,6-

dichlorogentisic acid (DCGA) in cotton matrices using high performance liquid chromatography 

with triple-quadrople mass spectrometric (LC-MS/MS) analysis. The method was used for data 

collection in the cotton crop field trial, processing, and storage stability studies reviewed under 

DP# 404821. 

Briefly, samples were extracted with acetonitrile:water (40:60, v:v). An aliquot of the extract 

was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate was partitioned with ethyl 

acetate:isooctane (20:80, v:v). Water was added to the organic phase and the sample was 

concentrated by evaporation until only the aqueous solution remained. The samples were 

acidified and analyzed using LC/MS/MS. Stable-labeled internal standards for each analyte 

('3C6-Dicarnba, 13C6-5-Hydroxydicamba, 13C6-DCSA, and 13C6-DCGA) were used to normalize 

for matrix effects and procedural recovery. The method monitors a single ion transition for each 

analyte. 

The limit of quantitation (LOQ), determined as the lowest limit of method validation (LLMV). 

for dicamba. 5-0H dicamba, DCSA and DCGA was 0.02 ppm for each analyte in undelinted 

cotton seed, meal, hulls, and alkali refined oi l; and 0.04 ppm for gin byproducts. The limit of 

detection (LOO) in cotton seed, statistically determined from the LLMV, was 0.0089, 0.0057, 

0.0035, and 0.0041 ppm for dicamba, 5-0H dicamba, DCSA and DCGA, respectively. LODs 

were not determined for cotton gin byproduct or processed commodities. 

The method was successfully validated using samples of undelinted cotton seed, meal, hulls, and 

oil fortified with each analyte at 0.02, 0.20, and I 0 ppm; and cotton gin byproducts fortified with 

0408384/MRID No. 48728702 Page I oflO 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 2 of 10

each analyte at 0.04, 0.40, and 10 ppm. Mean recoveries were within the acceptable range of 

70% to 120% with the coefficient of variation less than 20% for each matrix tested.

No confirmatory analysis procedures were included for the method, and no interference study 

was submitted; however, because the method has not been proposed for enforcement, 

confirmatory analysis procedures are not required.

An independent laboratory validation (ILV) was not submitted and is not required in support of a 

data collection method. 

Monsanto submitted radiovalidation data to evaluate the efficiency of the extraction 

methodology presented in Method AG-ME-1381-01. Average extractabilities from gin 

byproduct and cotton seed using Method AG-ME-1381-01 extraction procedures (67.07% and 

24.08%), were similar to normalized extractabilities obtained from gin byproduct and cotton seed

samples in the metabolism study (MRID 48728701) using multiple acetonitrile:water extractions 

(67.76% and 24.97%). Additionally, residue levels of dicamba, DCGA, and DCSA in the acidic 

post-evaporation solutions obtained using LC/MS/MS method AG-ME-1381-01, were similar to 

the residue levels in the metabolism samples as determined by 14C-HPLC profiles of hydrolyzed 

extracts. The extraction efficiencies for dicamba, DCGA, and DCSA, respectively, as 

determined by the reviewer, were 106%, 101%, and 121% in the undelinted seed samples, and 

83%, 79%, and 87% in the gin byproduct samples. Monsanto also investigated the recovery of 

radioactivity through the post-extraction steps of method AG-ME-1381-01. Overall postextraction recovery was 31.31% in undelinted cotton seed and 50.20% in cotton gin byproducts. 

The majority of the loss was in the partitioning step. 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, analytical method test data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document D408384.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. No deviations from regulatory requirements were reported which 

would have an impact on the validity of the study.

A. BACKGROUND INFORMATION

Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a selective benzoic acid herbicide registered 

for the control of weeds prior to their emergence. The dicamba Reregistration Eligibility 

Decision (RED) was issued December 2005. The chemical structure and nomenclature of 

dicamba and its metabolites 5-OH dicamba, DSCA, and DCGA are presented in Table A.1. The 

physicochemical properties of the technical grade of dicamba acid are presented in Table A.2. 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 3 of 10

TABLE A.1. Test Compound Nomenclature.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Not applicable

Compound

Common name 5-Hydroxy-dicamba

Company experimental name 5-OH dicamba

IUPAC/CAS name 2,5-dichloro-3-hydroxy-6-methoxybenzoic acid

CAS registry number 7600-50-2

Compound

Common name DCSA; 3,6-dichlorosalicylic acid

Company experimental name MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7

Compound

Common name DCGA; 3,6-dichlorogentistic acid

Company experimental name MON 52724

IUPAC/CAS name 2,5-dichloro-3,6-dihydroxybenzoic acid

CAS registry number 18688-01-2
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 4 of 10

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED, DP# 317699, 12/20/05, 

C. Olinger pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)

B. MATERIALS AND METHODS

B.1. Data-Gathering Method

Monsanto has submitted an analytical method description and validation data for a data 

collection method, AG-ME-1381-01, for the determination of residues of dicamba and its 

metabolites, 5-OH dicamba, DCSA and DCGA in cotton matrices using LC/MS/MS analysis. 

B.1.1. Principle of the Method:

Briefly, samples were extracted with acetonitrile:water (40:60, v:v). An aliquot of the extract 

was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate was partitioned with ethyl 

acetate:isooctane (20:80, v:v). Water was added to the organic phase and the sample was 

concentrated by evaporation until only the aqueous solution remained. The samples were 

acidified and analyzed using LC/MS/MS. Stable-labeled internal standards for each analyte 

(

13C6-Dicamba, 13C6-5-Hydroxydicamba, 13C6-DCSA, and 13C6-DCGA) were used to normalize 

for matrix effects and procedural recovery. The method monitors a single ion transition for each

analyte.

TABLE B.1.1. Summary Parameters for the Analytical Method Used for the Quantitation of the 

Residues of Dicamba and Dicamba Metabolites in Cotton Matrices.

Method ID AG-ME-1381-01

Analyte(s) Dicamba, 5-OH dicamba, DCSA and DCGA

Extraction solvent/technique Cotton matrices were extracted with acetonitrile (ACN)/water (40:60, v:v). 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 5 of 10

TABLE B.1.1. Summary Parameters for the Analytical Method Used for the Quantitation of the 

Residues of Dicamba and Dicamba Metabolites in Cotton Matrices.

Cleanup strategies An aliquot of the extract was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate

was partitioned with ethyl acetate:isooctane (20:80, v:v). Water was added to the organic 

phase and the sample was concentrated by evaporation until only the aqueous solution 

remained. The sample was acidified and analyzed by LC/MS/MS. 

Instrument/Detector LC/MS/MS using a Betasil Phenyl column. Quantitation of residues is performed using 

MS/MS turbo ion spray ionization in the negative ion MRM mode.

The following ions are monitored:

Dicamba: 219→175 m/z

5-OH dicamba: 237→193 m/z

DCSA: 205→161 m/z

DCGA: 221→177 m/z

Internal Standards

13C6-Dicamba: 225→181 m/z

13C6-5-Hydroxydicamba: 243→199 m/z

13C6-DCSA: 211→167 m/z

13C6-DCGA: 227→183 m/z

Standardization method Internal (13C6-Dicamba, 13C6-5-Hydroxydicamba, 13C6-DCSA, and 13C6-DCGA) and external 

standardization using mixed standards was used. A calibration curve is constructed where the 

peak area is plotted versus the analyte concentration using linear regression and a correlation 

coefficient of 0.990 or greater is obtained.

Stability of std solutions Stock solutions (100 μg/ml) were reported to be stable for at least 201 days.

Calibration standards (0.005 to 0.500 μg/mL) were reported to be stable for dicamba, 5-OH 

dicamba and DCSA at the 0.005 μg/mL concentration and above for at least 175 days and for 

DCGA at the 0.010 μg/mL concentration and above for at least 32 days.

Retention times (minutes) Dicamba: 2.7

5-OH dicamba: 1.3

DCSA: 5.6

DCGA: 1.7

B.2. Enforcement Method

A gas chromatography method with electron capture detection (GC/ECD) is the current 

enforcement method for residues of dicamba in/on plant commodities (Method AM-0691B0297-4).

C. RESULTS AND DISCUSSION

C.1. Data-Gathering Method

Method validation data are presented in Table C.1.1. Acceptable method validation recoveries 

for method AG-ME-1381-01 were obtained for all analytes from samples undelinted cotton seed 

at 0.02, 0.20, and 10 ppm; cotton meal, hulls, and oil at 0.02 and 0.20 ppm; and cotton gin 

byproducts at 0.04, 0.40, and 10 ppm. Mean recoveries were within the acceptable range of 70% 

to 120% with the coefficient of variation less than 20% for each matrix tested. Apparent 

residues of dicamba and its metabolites, 5-OH dicamba, DCSA and DCGA were each < LLMV 

in/on two samples each of seed (<0.02 ppm), gin byproducts (<0.04 ppm), meal, hulls, and alkali 

refined oil (<0.02 ppm). The fortification levels used in method validation are adequate to 

bracket expected residue levels in/on cotton matrices. 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 6 of 10

The method characteristics for AG-ME-1381-01 are summarized in Table C.1.2. The LOQ, 

determined as the LLMV, was 0.02 ppm for each analyte in undelinted cotton seed, meal, hulls, 

and alkali refined oil; and 0.04 ppm for each analyte in gin byproducts. The LOD in cotton 

seed, statistically determined from the LLMV, was 0.0089, 0.0057, 0.0035, and 0.0041 ppm for 

dicamba, 5-OH dicamba, DCSA and DCGA, respectively. LODs were not determined for cotton 

gin byproduct or processed commodities.

No confirmatory analysis procedures were included for the method, and no interference study 

was submitted; however, because the method has not been proposed for enforcement, 

confirmatory analysis procedures are not required.

Monsanto also submitted radiovalidation data. In the first part of the study, Monsanto compared 

the amount of radioactivity extracted from cotton seed and gin byproduct samples obtained from 

the metabolism study (MRID 48728701) using multiple acetonitrile:water extractions, to the 

amount of radioactivity extracted using the analytical method AG-ME-1381-01 extraction 

procedures. The extractabilities were similar: for gin byproducts and undelinted cotton seed, 

respectively, normalized extractabilities from the metabolism study were 67.76% and 24.97% 

and average extractabilities from method AG-ME-1381-01 were 67.07% and 24.08%. 

In the second part of the radiovalidation study, Monsanto investigated the recovery of 

radioactivity through the post-extraction steps of method AG-ME-1381-01. Overall postextraction recovery was 31.31% in undelinted cotton seed and 50.20% in cotton gin byproducts. 

The majority of the loss was in the partitioning step. Average percent recoveries for the 

hydrolysis, organic partition, aqueous partition, and acidic post-evaporation steps, respectively, 

were 87.06%, 57.21%, 62.98%, and 62.87% in cotton seed and 82.65%, 67.98%, 39.10%, and 

89.34% in gin byproducts. The study notes that losses in the partitioning step may be due to 1) 

water solubility of a percentage of the residues (e.g., polar residues formed by degradation of 

dicamba to small molecules and incorporation into natural products such as sugars), especially 

for seed, and, 2) incomplete partitioning of the analytes into the organic phase. The study also 

notes that the use of internal standards in this method compensates for any procedural losses 

incurred in the hydrolysis, partitioning, and evaporation steps.

In the third part of the radiovalidation study Monsanto compared the residue quantitation results 

of the acidic post-evaporation solutions obtained using LC/MS/MS method AG-ME-1381-01,

with the actual residue levels in the metabolism samples as determined by 14C-HPLC profiles of 

hydrolyzed extracts (MRID 48728701). These results are presented in Table C.1.3. The 

extraction efficiencies for dicamba, DCGA, and DCSA, respectively, were determined by the 

reviewer to be 106%, 101%, and 121% in the undelinted seed samples, and 83%, 79%, and 87% 

in the gin byproduct samples. 

TABLE C.1.1 Recovery Results from Method Validation of Cotton Matrices using the Data-Gathering 

Analytical Method. Standards were prepared in acetonitrile.

Matrix Spiking Level

(ppm)

Recoveries Obtained1

(%)

Mean Recovery ± SD (CV)1

(%)

Dicamba

Cotton seed 0.005 187, 73, 172, 105, 102 128 ± 49 (38)
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 7 of 10

TABLE C.1.1 Recovery Results from Method Validation of Cotton Matrices using the Data-Gathering 

Analytical Method. Standards were prepared in acetonitrile.

Matrix Spiking Level

(ppm)

Recoveries Obtained1

(%)

Mean Recovery ± SD (CV)1

(%)

0.01 129, 149, 93, 78, 125 115 ± 29 (25)

0.02 119, 100, 123, 101, 124 113 ± 12 (10)

0.20 94.0, 96.0, 94.5, 96.5, 99.5 96.1 ± 2.2 (2.2)

10 68.3, 90.5, 90.6, 100, 98.4 89.6 ± 13 (14)

Cotton gin byproducts 0.04 99.8, 92.5, 88.0, 122, 119 104 ± 15 (15)

0.40 97.0, 98.5, 101, 97.5, 104 99.5 ± 2.7 (2.7)

10 87.8, 90.5, 82.4, 85.1, 87.8 86.7 ± 3.1 (3.5)

Cotton meal 0.02 102, 101, 98.0, 111, 108 104 ± 5.3 (5.1)

0.20 96.5, 98.5, 95.5, 100, 94.0 96.9 ± 2.4 (2.5)

Cotton hulls 0.02 96.5, 100, 106, 99.0, 98.5 100 ± 3.4 (3.4)

0.20 96.5, 101, 102, 100, 99.0 100 ± 2.1 (2.1)

Cotton alkali refined oil 0.02 99.0, 96.0, 97.0, 98.5, 97.5 97.6 ± 1.2 (1.2)

0.20 99.0, 100, 105, 98.5, 97.0 100 ± 2.8 (2.9)

5-OH dicamba

Cotton seed 0.005 68, 56, 101, 84, 105 82.9 ± 21 (25)

0.01 106, 97, 76, 110, 82 94.1 ± 15 (16)

0.02 96.0, 97.5, 115, 117, 114 108 ± 10 (9.3)

0.20 97.5, 104, 105, 104, 101 102 ± 3.0 (2.9)

10 69.1, 89.6, 79.4, 93.2, 104 87.1 ± 13 (15)

Cotton gin byproducts 0.04 124, 106, 98.0, 96.5, 108 106 ± 11 (10)

0.40 111, 113, 106, 116, 109 111 ± 3.6 (3.3)

10 113, 98.7, 99.4, 101, 84.7 99.4 ± 10 (10)

Cotton meal 0.02 72.0, 108, 92.0, 77.0, 91.5 88.1 ± 14 (16)

0.20 98.0, 93.5, 87.5, 98.5, 89.5 93.4 ± 4.9 (5.3)

Cotton hulls 0.02 86.5, 78.0, 106, 89.0, 97.0 91.2 ± 10 (11)

0.20 114, 107, 117, 98.5, 105 108 ± 7.4 (6.8)

Cotton alkali refined oil 0.02 94.5, 101, 79.0, 92.0, 88.0 90.8 ± 8.0 (8.8)

0.20 110, 103, 88.0, 110, 100 102 ± 9.0 (8.8)

DCGA

Cotton seed 0.005 140, 115, 88, 98, 129 114 ± 22 (19)

0.01 90, 108, 96, 79, 104 95.6 ± 11 (12)

0.02 81.0, 98.0, 92.5, 77.0, 86.0 86.9 ± 8.5 (9.8)

0.20 90.0, 87.0, 88.0, 84.0, 95.5 88.9 ± 4.3 (4.8)

10 73.4, 95.7, 89.2, 94.4, 90.4 88.6 ± 8.9 (10)

Cotton gin byproducts 0.04 66.8, 87.5, 88.3, 89.8, 69.5 80.4 ± 11 (14)

0.40 99.3, 95.5, 99.0, 94.8, 96.5 97.0 ± 2.0 (2.1)

10 101, 94.1, 105, 98.9, 104 101 ± 4.4 (4.3)

Cotton meal 0.02 98.5, 108, 102, 103, 102 102 ± 3.3 (3.2)

0.20 87.5, 86.0, 84.5, 87.5, 84.5 86.0 ± 1.5 (1.7)

Cotton hulls 0.02 116, 117, 115, 121, 112 116 ± 3.4 (2.9)

0.20 88.5, 86.0, 85.5, 84.0, 82.0 85.2 ± 2.4 (2.8)

Cotton alkali refined oil 0.02 100, 102, 98.5, 103, 113 103 ± 5.7 (5.5)

0.20 96.5, 89.0, 91.5, 91.5, 90.5 91.8 ± 2.8 (3.1)
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 8 of 10

TABLE C.1.1 Recovery Results from Method Validation of Cotton Matrices using the Data-Gathering 

Analytical Method. Standards were prepared in acetonitrile.

Matrix Spiking Level

(ppm)

Recoveries Obtained1

(%)

Mean Recovery ± SD (CV)1

(%)

DCSA

Cotton seed 0.005 88, 95, 90, 134, 98 101 ± 19 (19)

0.01 70, 84, 102, 96, 98 89.8 ± 13 (15)

0.02 99.5, 82.0, 97.0, 97.0, 94.5 94.0 ± 6.9 (7.4)

0.20 94.5, 99.5, 105, 95.5, 101 98.9 ± 4.0 (4.1)

10 80.7, 92.1, 95.1, 93.1, 96.9 91.6 ± 6.4 (6.9)

Cotton gin byproducts 0.04 79.0, 87.3, 75.5, 75.3, 80.5 79.5 ± 4.9 (6.1)

0.40 90.5, 83.5, 92.8, 87.0, 91.0 89.0 ± 3.7 (4.2)

10 110, 101, 91.8, 109, 98.8 102 ± 7.6 (7.4)

Cotton meal 0.02 101, 95.5, 100, 89.5, 97.5 96.5 ± 4.4 (4.5)

0.20 82.0, 83.5, 85.5, 91.0, 89.0 86.2 ± 3.8 (4.4)

Cotton hulls 0.02 109, 102, 93.5, 97.0, 96.0 100 ± 6.1 (6.2)

0.20 95.5, 102, 91.5, 100, 99.0 97.4 ± 3.9 (4.0)

Cotton alkali refined oil 0.02 102, 93.0, 89.5, 92.5, 100 95.2 ± 5.1 (5.3)

0.20 103, 106, 100, 104, 105 103 ± 2.1 (2.0)

1 As calculated by the reviewer.

TABLE C.1.2 Characteristics for the Data-Gathering Analytical Method Used for the Quantitation of 

Dicamba and Dicamba Metabolites in Cotton Matrices.

Analyte(s) Dicamba, 5-OH dicamba, DCSA and DCGA

Equipment ID Shimadzu Prominence HPLC equipped with a Betasil Phenyl HPLC column (50 mm x 3

mm x 3 μm). Quantitation of residues is performed using an Applied Biosystems API 5500 

MS/MS using turbo ion spray ionization operated in the negative-ion multiple reaction 

monitoring (MRM) mode.

Limit of quantitation (LOQ) The LOQs, determined as the LLMV, were 0.02 ppm for each analyte in cotton seed, meal, 

hulls, and oil; and 0.04 ppm in gin by products.

Calculated LOQs were determined for cotton seed based on replicate determinations at the 

LLMV. The LOQs were 0.0266 ppm for dicamba, 0.0171 ppm for 5-OH dicamba, 0.0105 

ppm for DCSA, and 0.0121 ppm DCGA.

Limit of detection (LOD) The LODs, defined as the t0.99 confidence interval times the standard deviation of the 

fortified replicates at the LLMV, were determined for cotton seed. The LODs were 0.0089 

ppm for dicamba, 0.0057 ppm for 5-OH dicamba, 0.0035 ppm for DCSA and 0.0041 ppm

for DCGA.

Accuracy/Precision Percent recoveries and coefficients of variance (CVs) indicate acceptable accuracy/precision 

at 0.02, 0.20, and 10 ppm for dicamba and its metabolites in seed; at 0.02 and 0.20 ppm in 

meal, hulls, and oil; and at 0.04, 0.40, and 10 ppm for gin byproducts. Average recovery 

ranges (and CVs) were 86.7-113% (1.22-14.6) for dicamba, 87.1-111% (2.90-16.1) for 5-

OH dicamba, 79.5-103% (2.01-7.40) for DCSA, and 80.4-116 (1.74-14.0) for DCGA. See 

Table C.1.1 above.

Reliability of the Method/ [ILV] An independent laboratory method validation [ILV] was not conducted.

Linearity The method/detector response was linear (coefficient of determination, r2= ≥0.99) within the 

range of 0.005 - 0.50 μg/mL.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 9 of 10

TABLE C.1.2 Characteristics for the Data-Gathering Analytical Method Used for the Quantitation of 

Dicamba and Dicamba Metabolites in Cotton Matrices.

Specificity The control chromatograms generally have no peaks above the chromatographic background 

and the spiked sample chromatograms contain only the analyte peak of interest. In cotton 

gin byproducts, however, DCGA and 5-OH dicamba each had matrix interference for at 

least one lot that exceeded 30% of the LLMV. The study notes that chromatographic 

interference may be a problem in some matrices. Gradient conditions and use of MS with 

MRM analysis greatly reduces the interferences for these samples. The study also notes that 

there are no interferences from 2,4-dichlorophenoxyacetic acid or 2,4-dichlorophenylacetic 

acid, which have the same mass transitions as dicamba and DCSA, respectively.

Interferences from other pesticides are unknown, however, none are expected due to the 

high level of specificity of the LC/MS/MS analysis.

Peaks were well defined and symmetrical. There appeared to be no carryover to the 

following chromatograms.

Table C.1.3. Extraction Efficiency of Method AG-ME-1381-01 As Compared to the Metabolism Study Extraction

Method

Matrix Analyte Extraction Method Radioactive Residues

(ppm) [Average]

Extraction 

Efficiency1

(%)

Seed Dicamba Metabolism study 0.0102 106

Method AG-ME-1381-01 0.0098, 0.0119 [0.0108]

DCGA Metabolism study 0.0224 101

Method AG-ME-1381-01 0.0227, 0.0227 [0.0227]

DCSA Metabolism study 0.0532 121

Method AG-ME-1381-01 0.0634, 0.0658 [0.0646]

Gin 

Byproduct

Dicamba Metabolism study 2.83 83

Method AG-ME-1381-01 2.31, 2.37 [2.34]

DCGA Metabolism study 4.63 79

Method AG-ME-1381-01 3.82, 3.50 [3.66]

DCSA Metabolism study 16.1 87

Method AG-ME-1381-01 13.99, 14.09 [14.04]

1

 Extraction efficiency = (residues determined by residue method ÷ residues determined in metabolism study)*100.

C.2. Enforcement Method

A gas chromatography method with electron capture detection (GC/ECD) is the current 

enforcement method for residues of dicamba in/on plant commodities (Method AM-0691B0297-4).

C.3. Independent Laboratory Validation

An independent laboratory validation (ILV) study was not included as a part of this submission; 

however, no additional information is required because ILV is not generally required for data 

collection methods.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.2.1, 7.2.2, and 7.2.3/OPPTS 860.1340/OECD IIA 4.2.5, 4.2.6 and 4.3

Residue Analytical Method - Cotton

D408384/MRID No. 48728702 Page 10 of 10

D. CONCLUSION

Adequate method validation data have been submitted for the analytical method AG-ME-1381-

01 for the determination of residues of dicamba, 5-OH dicamba, DCSA and DCGA in cotton 

commodities. The method has been adequately validated with accuracy and precision over the 

range of 0.02 to 10 ppm for cotton seed; 0.02 to 0.20 ppm for meal, hulls, and oil, and 0.04 to 10 

ppm for cotton gin byproducts. Mean recoveries were within acceptable range of 70% to 120%

with the coefficient of variation less than 20% for each matrix tested. The data are sufficiently 

representative of the expected residue levels in cotton seed, gin byproducts, meal, hulls, and oil. 

Acceptable radiovalidation data were submitted. 

No confirmatory analysis procedures were included for the method, and no interference study 

was submitted; however, because the method has not been proposed for enforcement, 

confirmatory analysis procedures are not required.

An ILV was not submitted and is not required in support of a data collection method. 

E. REFERENCES

DP No.: D317699

Subject: Dicamba. Residue Chemistry Considerations for the Reregistration Eligibility 

Decision (RED) Document. Summary of Analytical Chemistry and Residue Data.

From: C. L. Olinger

To: K. Tyler

Date: 12/20/2005

MRIDs: None

F. DOCUMENT TRACKING

Petition Number(s): 2F8067

DP Barcode(s): 408384

PC Code: 029801, 029802, 029806, 128931, 128944, & 129043

Template Version September 2003
Dicarnba/MON 11900/PC Code 128931 /Monsanto Company 

r¥~ _::::. ·· I - ·- OACO 7.4. 1/7.4.2/0PPTS 860.1500/0ECD llA 6.3.1 , 6.3.2, 6.3.3 and JllA 8.3.1, 8.3.2, 8.3.3 

Crop Field Trial/ Residue Decline - Dicamba-Tolerant Conon (Event MO 8870 I) 

Primary Evaluator Date: 11115/2012 

Versar, Inc. 

,7 

Approved by / .rr- ~ A,....,.-,,~;......___./ Date: 04/22/2013 _.-" 

Peter Savoia, Chemist, OCSPP-HED-RAB VNif 

This DER was originally prepared under contract by Vcrsar. Inc. (6850 Vcrsar Center. Springfidd. VA 22 151: submiued 

( 11115/2012). The DER has been reviewed by I-JED and revised to renec1 current Office of Pesticide Programs (OPP) policies. 

STUDY REPORT: 

48728703 Maher, D.; Foster, J. (2011) Magnitude of Dicamba Residues in Cotton Raw 

Agricultural and Processed Commodities following Applications of Dicamba-Based 

Formulations to MON 88701. Project Number: REG/ I 0/062/0CR, MSL0024072. Unpublished 

study prepared by Monsanto Company, Carringers, Inc. and GLP Technologies. 603 p. 

EXECUTIVE SUMMARY: 

Monsanto has submitted field trial data for dicamba on dicamba-tolerant cotton, identified as 

Event MON 88701 (formerly GH_S26695). Event MON 88701 cotton expresses a modified 

dicamba mono-oxygenase (DMO) gene derived from Stenotrophomonas maltophilia and the 

bialaphos resistance (BAR) gene isolated from Streptomyces hygroscopicus. The expression of 

DMO confers dicamba tolerance and the expression of BAR confers glufosinate tolerance to 

Event MON 8870 I cotton. Thirteen field trials were conducted in the United States during the 

2010 growing season in the North American Free Trade Agreement (NAFTA) Growing Zones 2 

(GA and SC; 2 trials), 4 (AR. LA, and MO: 3 trials). 6 (TX; l trial), 8 (OK and TX: 5 trials). and 

10 (CA; 2 trials). 

Each trial consisted of one untreated and three to four treated plots. Each treated plot fo llowed 

one of three treatment types: three broadcast applications applied at pre-emergence. 6-leaf, and 

151 white flower + 15 days [TRT 2]; three broadcast applications applied at pre-emergence, first 

open boll, and 7-days prior to harvest [TRT 3]; and four foliar broadcast applications applied at 

6-leaf, l st white flower + 15 days, first open boll, and 7 days prior to harvest [TR Ts 4 and 5]. 

Applications to plots 2, 3, and 4 were made using a 4 lb ae/gal water soluble concentrate (SL) 

formu lation of dicamba diglycolamine salt (Clarity Herbicide; MON 54140); plot 5 applications 

were made using a 5 lb ae/gal SL formulation of dicamba monoethanolamine salt (MON 11 968) 

to provide bridging data. The total application rate for all treatment types was 2.0-2.l lb ae/A 

(2.2-2.4 kg ae/ha). For TRT 2, application I was applied at 0.98-1.0 lb ae/A (1. 1 kg ae/ha) and 

applications 2 and 3 were applied at 0.49-0.5 l lb ae/Napplication (0.55-0.57 kg 

ae/ha/application). Retreatment intervals (RTis) were 24-49 days between the first and second 

applications and 36-49 days between the second and third applications. For TRT 3. application 1 

was applied at 0.99-1 .0 lb ae/A ( 1.1 kg ae/ha) and appli cations 2 and 3 were applied at 0.49-0.52 

lb ae/N application (0.55-0.58 kg ae/ha/application), for a total seasonal rate of 2.0 lb ae/A (2.2 

kg ae/ha). RTls were 97-178 days between the first and second applications and 5-63 days 

between the second and third applications. For TRTs 4 and 5, applications were applied at 0.49-

0408384fMRID No. 48728703 Page I of28 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 2 of 28

0.52 lb ae/A/application (0.55-0.58 kg ae/ha/application). RTIs were 36-49 days between the 

first and second applications, 32-88 days between the second and third applications, and 5-63 

days between the third and fourth applications. A summary of the use patterns is provided in the 

table below. 

TRT Number 

of Sites

EP Growth Stages/ Target Application Rates lb ae/A (kg ae/ha)

Pre-emergence 6 Leaf 1

st White Flower 

+ 15 days

First Open 

Boll

7 Days 

Prior to 

Harvest

1 13 -- -- -- -- -- --

2 13 4 lb ae/gal SL 1.0 (1.1) 0.50 (0.56) 0.50 (0.56) -- --

3 13 4 lb ae/gal SL 1.0 (1.1) -- -- 0.50 (0.56) 0.50 (0.56)

4 13 4 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)

5 4 5 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)

Applications for all treatments were made using ground equipment (backpack, hand-held and 

tractor-mounted sprayers) in spray volumes of 18.8-21.6 gal/A (176-202 l/ha) and included an 

nonionic surfactant (NIS) and ammonium sulfate (AMS) at all trial sites. 

Undelinted cotton seed was collected mechanically with a cotton picker (n=3) or a cotton stripper

(n=3) or by hand (n=7) at normal harvest: 49-105-day preharvest interval (PHI) for TRT 2 and 6-

8-day PHI for TRTs 3-5. Additional samples of cotton seed were collected from two trials at 

PHIs of 43/99, 49/105, 56/112, and 63/119 days for TRT 2 and 1, 7, 14, and 21 days for TRT 4 

to assess residue decline. Cotton gin byproduct samples were collected from three sites using a 

cotton stripper at normal harvest (82-84-day PHI for TRT 2; 6-7-day PHI for TRT 4). 

Samples were analyzed for residues of dicamba and metabolites 5-hydroxydicamba (5-OH 

dicamba), 3,6-dichlorosalicylic acid (DCSA), and 3,6-dichlorogentisic acid (DCGA) using a high 

performance liquid chromatography method with tandem mass spectrometry detection

(LC/MS/MS). The limit of quantitation (LOQ, equivalent to the lowest level of method 

validation; LLMV) was 0.02 ppm for all analytes in undelinted cotton seed and 0.04 ppm for all 

analytes in cotton gin byproducts. The method was adequate for data validation based on 

acceptable method and concurrent recovery data. The fortification levels used in concurrent 

method recovery were adequate to bracket expected residue levels. Concurrent recoveries were 

corrected for apparent residues in controls; residues in treated samples were not corrected for 

residues in controls. We note that the analytical method does not specify conversion of 

metabolite residues to parent equivalents; therefore, quantifiable residues of 5-OH dicamba, 

DCSA, and DCGA were converted to parent equivalents by the study reviewer using a molecular 

weight conversion factor of 0.933, 1.068, and 0.991, respectively.

Dicamba, 5-OH dicamba, and DCSA undelinted cotton seed samples were stored for 13-146 

days (0.4-4.8 months) from collection to analysis; DCGA undelinted cotton seed samples were 

stored for 13-285 days (0.4-9.4 months). Gin byproduct samples for all analytes were stored 

from 17-27 days (0.6-0.9 months) from collection to analysis. All samples were analyzed within 

0 to 2 days of extraction. Samples were stored below freezing at the field sites and at -20 °C at 

the analytical laboratory prior to extraction. A storage stability study for dicamba, DCGA, and 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 3 of 28

DCSA on cotton was submitted in conjunction with the field trial study (refer to the 860.1380 

der for MRID 48728704). The stability of 5-OH dicamba was not determined concurrently 

because it was not found in undelinted cotton seed. These data are acceptable to support the 

storage conditions and durations of the undelinted cotton seed samples from the submitted field 

trials. Storage stability data for cotton gin byproduct was not provided; however, storage 

stability data is not required as the samples were analyzed within 30 days of harvest.

Following three broadcast applications of the 4 lb ae/gal SL formulation of dicamba (formulated 

as the diglycolamine salt), which were applied at pre-emergence, the 6-leaf stage, and first white 

flower + 15 days for a total rate of 2.0 lb ae/A (2.2 kg ae/ha) (TRT 2), combined residues (and 

per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA (expressed in parent 

equivalents) were <0.08-<0.39 (<0.08-<0.39) ppm in/on undelinted cotton seed collected at PHIs 

of 49-105 days and <0.67-<2.34 (<0.73-<2.33) ppm in/on gin byproducts collected at PHIs of 

82-84 days.

Following three broadcast applications of the 4 lb ae/gal SL formulation of dicamba (formulated 

as the diglycolamine salt), which were applied at pre-emergence, the first open boll stage, and 7 

days prior to harvest for a total rate of 2.0 lb ae/A (2.2 kg ae/ha) (TRT 3), combined residues 

(and per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA (expressed in parent 

equivalents) were <0.12-<2.24 (<0.13-<1.66) ppm in/on undelinted cotton seed collected at a 6-

8-day PHI.

Following four foliar broadcast applications of the 4 lb ae/gal SL formulation of dicamba 

(formulated as the diglycolamine salt), which were applied at the 6-leaf stage, the first white 

flower + 15 days, the first open boll, and 7 days prior to harvest for a total rate of 2.0-2.1 lb ae/A 

(2.2-2.4 kg ae/ha) (TRT 4), combined residues (and per trial averages) of dicamba, 5-OH 

dicamba, DCGA, and DCSA (expressed in parent equivalents) were <0.15-<2.02 (<0.21-<1.86) 

ppm in/on undelinted cotton seed collected at a 6-8-day PHI and <5.50-34.6 (<5.51-<33.7) ppm 

in/on gin byproducts collected at a 6-7-day PHI. Corresponding combined residues (and per trial 

averages) in side-by-side trials treated with the 5 lb ae/gal SL formulation of dicamba formulated 

as the monoethanolamine salt (TRT 5) were <0.24-<1.00 (<0.29-<0.82) ppm in/on undelinted 

cotton seed. Average combined residues in the diglycolamine salt formulation trials were 

slightly higher (approximately 1.5x) than the corresponding residues in the monoethanolamine 

salt formulation trials. 

Treatment plots 3 and 4 showed the highest average combined residues (0.76 ppm), followed 

closely by treatment plot 5 (average of 0.52 ppm). Treatment plot 2 had the lowest average 

combined residues (average of 0.12 ppm). Lower residue levels obtained from treatment plot 2 

are consistent with the earlier application timings at these plots. 

For the TRT 2 residue decline samples, average residues of dicamba, 5-OH dicamba, DCGA, 

and DCSA in/on undelinted cotton seed were at or <LOQ in both studies; therefore, residue 

decline could not be assessed. For the TRT 4 residue decline samples, average residues of 

dicamba decreased in/on undelinted cotton seed with increasing PHI. Average residues of 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 4 of 28

DCGA and DCSA increased with increasing PHI in the SC1 trial, and remained relatively 

constant in the TX1 trial. Residues of 5-OH dicamba were <LOQ in both studies; therefore, 

residue decline could not be assessed. 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document D408384.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance, and Data Confidentiality

statements were provided. No deviations from regulatory requirements were reported which 

would have an impact on the validity of the study.

A. BACKGROUND INFORMATION

Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a selective benzoic acid herbicide registered 

for the control of weeds prior to their emergence. The Dicamba Reregistration Eligibility 

Decision (RED) was issued December 2005. The chemical structure and nomenclature of 

dicamba and its metabolites 5-OH dicamba, DSCA, and DCGA are presented in Table A.1. The 

physicochemical properties of the technical grade of dicamba acid are presented in Table A.2. 

TABLE A.1. Test Compound Nomenclature.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Clarity® Herbicide: SL formulation containing 4 lb ae/gal

MON 11968: SL formulation containing 5 lb ae/gal

Compound
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 5 of 28

TABLE A.1. Test Compound Nomenclature.

Common name 5-Hydroxy-dicamba

Company experimental name 5-OH dicamba

IUPAC/CAS name 2,5-dichloro-3-hydroxy-6-methoxybenzoic acid

CAS registry number 7600-50-2

Compound

Common name DCSA; 3,6-dichlorosalicylic acid

Company experimental name MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7

Compound

Common name DCGA; 3,6-dichlorogentistic acid

Company experimental name MON 52724

IUPAC/CAS name 2,5-dichloro-3,6-dihydroxybenzoic acid

CAS registry number 18688-01-2

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED, DP# 317699, 12/20/05, 

C. Olinger pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 6 of 28

B. EXPERIMENTAL DESIGN

B.1. Study Site Information

Thirteen field trials were conducted on cotton in the United States during the 2010 growing 

season in NAFTA Zones 2 (GA and SC; 2 trials), 4 (AR, LA, and MO; 3 trials), 6 (TX; 1 trial), 8 

(OK and TX; 5 trials), and 10 (CA; 2 trials). 

Each trial consisted of one untreated and three to four treated plots. The plots were planted with 

dicamba-tolerant cotton, identified as Event MON 88701 (formerly GH_S26695). Event MON 

88701 cotton expresses a modified dicamba mono-oxygenase (DMO) gene derived from 

Stenotrophomonas maltophilia and the bialaphos resistance (BAR) gene isolated from 

Streptomyces hygroscopicus. The expression of DMO confers dicamba tolerance and the 

expression of BAR confers glufosinate tolerance to Event MON 88701 cotton. Each treated plot 

followed one of three treatment types: three broadcast applications applied at pre-emergence, 6-

leaf, and 1st white flower + 15 days [TRT 2]; three broadcast applications applied at preemergence, first open boll, and 7-days prior to harvest [TRT 3]; and four foliar broadcast 

applications applied at 6-leaf, 1st white flower + 15 days, first open boll, and 7 days prior to 

harvest [TRTs 4 and 5]. Applications to plots 2, 3, and 4 were made using a 4 lb ae/gal SL

formulation of dicamba diglycolamine salt (Clarity Herbicide; MON 54140); plot 5 applications 

were made using a 5 lb ae/gal SL formulation of dicamba monoethanolamine salt (MON 11968) 

to provide bridging data. The total application rate for all treatment types was 2.0-2.1 lb ae/A 

(2.2-2.4 kg ae/ha). For TRT 2, application 1 was applied at 0.98-1.0 lb ae/A (1.1 kg ae/ha) and 

applications 2 and 3 were applied at 0.49-0.51 lb ae/A/application (0.55-0.57 kg 

ae/ha/application). RTIs were 24-49 days between the first and second applications and 36-49

days between the second and third applications. For TRT 3, application 1 was applied at 0.99-

1.0 lb ae/A (1.1 kg ae/ha) and applications 2 and 3 were applied at 0.49-0.52 lb ae/A/application 

(0.55-0.58 kg ae/ha/application). RTIs were 97-178 days between the first and second 

applications and 5-63 days between the second and third applications. For TRTs 4 and 5, 

applications were applied at 0.49-0.52 lb ae/A/application (0.55-0.58 kg ae/ha/application). RTIs

were 36-49 days between the first and second applications, 32-88 days between the second and 

third applications, and 5-63 days between the third and fourth applications. A summary of the 

use patterns is provided in the table below. 

TRT Number 

of Sites

EP Growth Stages/ Target Application Rates lb ae/A (kg ae/ha)

Pre-emergence 6 Leaf 1

st White Flower 

+ 15 days

First Open 

Boll

7 Days 

Prior to 

Harvest

1 13 -- -- -- -- -- --

2 13 4 lb ae/gal SL 1.0 (1.1) 0.50 (0.56) 0.50 (0.56) -- --

3 13 4 lb ae/gal SL 1.0 (1.1) -- -- 0.50 (0.56) 0.50 (0.56)

4 13 4 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)

5 4 5 lb ae/gal SL -- 0.50 (0.56) 0.50 (0.56) 0.50 (0.56) 0.50 (0.56)
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 7 of 28

Applications for all treatments were made using ground equipment (backpack, hand-held and 

tractor-mounted sprayers) in spray volumes of 18.8-21.6 gal/A (176-202 l/ha) and included an 

NIS and an AMS at all trial sites. 

Undelinted cotton seed was collected mechanically with a cotton picker (n=3) or a cotton stripper 

(n=3) or by hand (n=7) at normal harvest: 49-105-day preharvest interval (PHI) for TRT 2 and 6-

8-day PHI for TRTs 3-5. Additional samples of cotton seed were collected from two trials 

conducted in SC and TX at PHIs of 43/99, 49/105, 56/112, and 63/119 days for TRT 2 and 1, 7, 

14, and 21 days for TRT 4 to assess residue decline; decline sampling times corresponded to 1 

day following the 7-day PHI application, normal harvest, 7±1 days following normal harvest, 

and 14±1 days following normal harvest. Cotton gin byproduct samples were collected from 

three sites (in TX and OK) using a cotton stripper at normal harvest (82-84-day PHI for TRT 2; 

6-7-day PHI for TRT 4). 

For each field trial, the petitioner presented the average minimum and maximum monthly 

temperatures and the total monthly rainfall for the study period, as well as the historical 

averages. Irrigation was used to supplement rainfall as needed. The petitioner reported that no 

unusual weather events occurred that negatively affected the residue trials; however, 

precipitation was greater than normal at the CA2, TX1, and TX4 sites and less than normal at the 

LA1, OK1, and OK2 sites. These conditions did not cause adverse crop growth and 

development, except at CA2 where cool temperatures and excess moisture in October and 

November kept the cotton from maturing at a normal rate. 

Trial conditions are presented in Table B.1.1. The study use pattern is presented in Table B.1.2, 

and the crop varieties grown are identified in Table C.3. 

TABLE B.1.1 Trial Site Conditions.

Trial Identification:

City, County, State; Year (Trial No.)

Soil characteristics

Type %OM1 pH1 CEC1

meq/100 g

Proctor, Crittenden, AR; 2010 (AR1) Clay 1.1 6.3 17.4

Porterville, Tulare, CA; 2010 (CA1) Sandy loam 0.5 8.2 Not reported

Visalia, Tulare, CA; 2010 (CA2) Sandy loam 1.11 7.2 5.6

Chula, Tift, GA; 2010 (GA1) Loamy sand Not reported

Cheneyville, Rapides, LA; 2010 (LA1) Silt loam 0.88 8.07 13.77

Fisk, Butler, MO; 2010 (MO1) Silt loam 1.4 5.2 9.0

Hinton, Caddo, OK; 2010 (OK1) Fine sandy loam 1.6 6.6 12.5

Dill City, Washita, OK; 2010 (OK2) Loamy sand 0.6 7.4 6.0

Elko, Barnwell, SC; 2010 (SC1) Loamy sand 1.0 6.1 3.6

Raymondville, Willacy, TX; 2010 (TX1) Clay loam 1.1 8.2 26.7

Levelland, Hockley, TX; 2010 (TX2) Sandy loam 0.59 7.9 10.35

Wolfforth, Lubbock, TX; 2010 (TX3) Sandy clay loam 0.6 7.6 10.1

Uvalde, Uvalde, TX; 2010 (TX4) Clay loam 2.2 7.9 25.4

1 These parameters are optional except in cases where their value affects the use pattern for the chemical.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 8 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Proctor, 

Crittenden, AR; 

2010 (AR1)

4 lb 

ae/gal

SL

2 1. Soil broadcast; Preemergence 20.1 

(188)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

29

3. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

38

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.1

(188)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st open 

boll

20.1

(188)

0.50

(0.56)

99

3. Foliar broadcast; 7 days prior 

to harvest

20.1

(188)

0.50

(0.56)

31

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.1

(188)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF + 15 

days

20.2

(189)

0.50

(0.56)

38

3. Foliar broadcast; 1st open 

boll

20.1

(188)

0.50

(0.56)

32

4. Foliar broadcast; 7 days prior 

to harvest

20.1

(188)

0.50

(0.56)

31

5 lb 

ae/gal 

SL

5 1. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF + 15 

days

20.2

(189)

0.50

(0.56)

38

3. Foliar broadcast; 1st open 

boll

20.2

(189)

0.50

(0.56)

32

4. Foliar broadcast; 7 days prior 

to harvest

20.1

(188)

0.50

(0.56)

31

Porterville, 

Tulare, CA; 

2010 (CA1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.5

(192)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.3

(190)

0.50

(0.56)

48

3. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.51

(0.57)

43

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.3

(190)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.2

(189)

0.51

(0.57)

136

3. Foliar broadcast; 7 days prior 

to harvest

20.4

(191)

0.51

(0.57)

28

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.2

(189)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.3

(190)

0.52

(0.58)

43

3. Foliar broadcast; 1st open 

boll

20.2

(189)

0.51

(0.57)

45

4. Foliar broadcast; 7 days prior 

to harvest

20.2

(189)

0.51

(0.57)

28
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 9 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Porterville, 

Tulare, CA; 

2010 (CA1)

(continued)

5 lb 

ae/gal 

SL

5 1. Foliar broadcast; 6-leaf 20.2

(189)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.2

(189)

0.52

(0.58)

43

3. Foliar broadcast; 1st open 

boll

20.1

(188)

0.50

(0.56)

45

4. Foliar broadcast; 7 days prior 

to harvest

20.0

(187)

0.50

(0.56)

28

Visalia, Tulare, 

CA; 2010 

(CA2)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.5

(192)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.1

(188)

0.50

(0.56)

41

3. Foliar broadcast; 1st WF + 15 

days

20.7

(194)

0.51

(0.57)

49

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.4

(191)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.3

(190)

0.51

(0.57)

178

3. Foliar broadcast; 7 days prior 

to harvest

20.5

(192)

0.50

(0.56)

7

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.6

(193)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.3

(190)

0.50

(0.56)

49

3. Foliar broadcast; 1st open 

boll

20.4

(191)

0.51

(0.57)

88

4. Foliar broadcast; 7 days prior 

to harvest

20.8

(195)

0.51

(0.57)

7

Chula, Tift, 

GA; 2010 

(GA1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.5

(192)

0.99

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.5

(192)

0.50

(0.56)

26

3. Foliar broadcast; 1st WF + 15 

days

20.2

(189)

0.51

(0.57)

43

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.6

(193)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.4

(191)

0.52

(0.58)

104

3. Foliar broadcast; 7 days prior 

to harvest

20.4

(191)

0.50

(0.56)

42

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.9

(195)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.0

(187)

0.50

(0.56)

43

3. Foliar broadcast; 1st open 

boll

19.8

(185)

0.51

(0.57)

35

4. Foliar broadcast; 7 days prior 

to harvest

20.4

(191)

0.50

(0.56)

42
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 10 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Chula, Tift, 

GA; 2010 

(GA1)

(continued)

5 lb 

ae/gal 

SL

5 1. Foliar broadcast; 6-leaf 20.9

(195)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.0

(187)

0.50

(0.56)

43

3. Foliar broadcast; 1st open 

boll

19.5

(182)

0.50

(0.56)

35

4. Foliar broadcast; 7 days prior 

to harvest

20.2

(189)

0.50

(0.56)

42

Cheneyville, 

Rapides, LA; 

2010 (LA1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.5

(192)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 19.0

(178)

0.51

(0.57)

27

3. Foliar broadcast; 1st WF + 15 

days

19.2

(180)

0.51

(0.57)

37

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.8

(195)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.1

(188)

0.50

(0.56)

97

3. Foliar broadcast; 7 days prior 

to harvest

21.6

(202)

0.52

(0.58)

33

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 19.2

(180)

0.52

(0.58)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

19.4

(181)

0.51

(0.57)

37

3. Foliar broadcast; 1st open 

boll

20.5

(192)

0.51

(0.57)

33

4. Foliar broadcast; 7 days prior 

to harvest

21.2

(198)

0.51

(0.57)

33

Fisk, Butler, 

MO; 2010 

(MO1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.0

(187)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

29

3. Foliar broadcast; 1st WF + 15 

days

20.0

(187)

0.50

(0.56)

42

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.0

(187)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st open 

boll

20.0

(187)

0.50

(0.56)

113

3. Foliar broadcast; 7 days prior 

to harvest

20.0

(187)

0.50

(0.56)

30

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.3

(190)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

42

3. Foliar broadcast; 1st open 

boll

20.0

(187)

0.50

(0.56)

42

4. Foliar broadcast; 7 days prior 

to harvest

20.0

(187)

0.50

(0.56)

30
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 11 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Hinton, Caddo, 

OK; 2010 

(OK1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 18.8

(176)

0.99

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.3

(190)

0.51

(0.57)

24

3. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

49

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 19.0

(178)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

19.8

(185)

0.50

(0.56)

107

3. Foliar broadcast; 7 days prior 

to harvest

20.6

(193)

0.51

(0.57)

27

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.3

(190)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

19.9

(186)

0.49

(0.55)

49

3. Foliar broadcast; 1st open 

boll

20.2

(189)

0.51

(0.57)

34

4. Foliar broadcast; 7 days prior 

to harvest

20.6

(193)

0.51

(0.57)

27

5 lb 

ae/gal

SL

5 1. Foliar broadcast; 6-leaf 19.8

(185)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

19.8

(185)

0.49

(0.55)

49

3. Foliar broadcast; 1st open 

boll

19.7

(184)

0.50

(0.56)

34

4. Foliar broadcast; 7 days prior 

to harvest

20.3

(190)

0.50

(0.56)

27

Dill City, 

Washita, OK; 

2010 (OK2)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 19.0

(178)

0.98

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 6-leaf 20.1

(188)

0.50

(0.56)

28

3. Foliar broadcast; 1st WF + 15 

days

19.7

(184)

0.49

(0.55)

49

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 19.2

(180)

0.99

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.3

(190)

0.50

(0.56)

109

3. Foliar broadcast; 7 days prior 

to harvest

20.1

(188)

0.50

(0.56)

43

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.2

(189)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

49

3. Foliar broadcast; 1st open 

boll

20.3

(190)

0.50

(0.56)

32

4. Foliar broadcast; 7 days prior 

to harvest

19.7

(184)

0.49

(0.55)

43
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 12 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Elko, Barnwell, 

SC; 2010 (SC1)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.3

(190)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.8

(195)

0.50

(0.56)

29

3. Foliar broadcast; 1st WF + 15 

days

20.6

(193)

0.50

(0.56)

38

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.2

(189)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.8

(195)

0.50

(0.56)

102

3. Foliar broadcast; 7 days prior 

to harvest

20.0

(187)

0.50

(0.56)

63

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.7

(194)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.6

(193)

0.50

(0.56)

38

3. Foliar broadcast; 1st open 

boll

20.6

(193)

0.50

(0.56)

35

4. Foliar broadcast; 7 days prior 

to harvest

19.9

(186)

0.50

(0.56)

63

Raymondville, 

Willacy, TX; 

2010 (TX1)

4 lb 

ae/gal

SL

2 1. Soil broadcast; Preemergence 20.3

(190)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 6-leaf 20.7

(194)

0.52

(0.58)

36

3. Foliar broadcast; 1st WF + 15 

days

20.9

(195)

0.52

(0.58)

46

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.4

(191)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st open 

boll

20.7

(194)

0.52

(0.58)

119

3. Foliar broadcast; 7 days prior 

to harvest

20.6

(193)

0.52

(0.58)

5

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.7

(194)

0.52

(0.58)

-- 2.1

(2.4)

NIS + AMS Harvested 

by hand

2. Foliar broadcast; 1st WF + 15 

days

20.8

(195)

0.52

(0.58)

46

3. Foliar broadcast; 1st open 

boll

20.7

(194)

0.52

(0.58)

37

4. Foliar broadcast; 7 days prior 

to harvest

20.9

(195)

0.52

(0.58)

5
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 13 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Levelland, 

Hockley, TX; 

2010 (TX2)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.4

(191)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 6-leaf 20.6

(193)

0.51

(0.57)

36

3. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

41

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.3

(190)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 1st open 

boll

19.7

(184)

0.49

(0.55)

118

3. Foliar broadcast; 7 days prior 

to harvest

19.8

(185)

0.49

(0.55)

37

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.0

(187)

0.49

(0.55)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 1st WF + 15 

days

20.0

(187)

0.49

(0.55)

41

3. Foliar broadcast; 1st open 

boll

20.4

(191)

0.50

(0.56)

41

4. Foliar broadcast; 7 days prior 

to harvest

20.0

(187)

0.49

(0.55)

37

Wolfforth, 

Lubbock, TX; 

2010 (TX3)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.1

(188)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 6-leaf 20.7

(194)

0.51

(0.57)

41

3. Foliar broadcast; 1st WF + 15 

days

19.8

(185)

0.49

(0.55)

36

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 20.2

(189)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 1

st open 

boll

20.0

(187)

0.49

(0.55)

125

3. Foliar broadcast; 7 days prior 

to harvest

19.7

(184)

0.49

(0.55)

30

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.2

(189)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Mechanical 

stripper

2. Foliar broadcast; 1st WF + 15 

days

20.1

(188)

0.50

(0.56)

36

3. Foliar broadcast; 1st open 

boll

20.2

(189)

0.50

(0.56)

48

4. Foliar broadcast; 7 days prior 

to harvest

20.1

(188)

0.50

(0.56)

30
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 14 of 28

TABLE B.1.2. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb 

ae/A

(kg 

ae/ha)

RTI2

(days)

Total 

Rate

lb ae/A

(kg 

ae/ha)

Uvalde, 

Uvalde, TX; 

2010 (TX4)

4 lb 

ae/gal 

SL

2 1. Soil broadcast; Preemergence 20.2

(189)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 6-leaf 20.1

(188)

0.50

(0.56)

49

3. Foliar broadcast; 1st WF + 15 

days

19.9

(186)

0.50

(0.56)

47

4 lb 

ae/gal 

SL

3 1. Soil broadcast; Preemergence 19.9

(186)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st open 

boll

21.5

(201)

0.52

(0.58)

132

3. Foliar broadcast; 7 days prior 

to harvest

19.7

(184)

0.49

(0.55)

29

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF + 15 

days

19.7

(184)

0.49

(0.55)

47

3. Foliar broadcast; 1st open 

boll

20.5

(192)

0.49

(0.55)

36

4. Foliar broadcast; 7 days prior 

to harvest

20.2

(189)

0.51

(0.57)

29

1 EP = End-use Product; Clarity [SL formulation containing 480 g/L dicamba formulated as the diglycolamine salt (4 lb ae/gal)]

and MON 11968 [SL formulation containing 600 g/L dicamba formulated as the monoethanolamine salt (5 lb ae/gal).

2 Retreatment Interval.

3 NIS = nonionic surfactant. AMS = ammonium sulfate.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 15 of 28

TABLE B.1.3. Trial Numbers and Geographical Locations.

NAFTA 

Growing Zones

Cotton

Submitted Requested1 

Canada U.S.

1 -- -- --

1A -- -- --

2 2 -- 1/1

3 -- -- --

4 3 -- 3/2

5 -- -- --

5A -- -- --

5B -- -- --

6 1 -- 1/1

7 -- -- --

7A -- -- --

8 5 -- 4/3

9 -- -- --

10 2 -- 3/2

11 -- -- --

12 -- -- --

13 -- -- --

14 -- -- --

15 -- -- --

16 -- -- --

17 -- -- --

18 -- -- --

19 -- -- --

20 -- -- --

21 -- -- --

Total 13 12/9

1

 As per OCSPP 860.1500, Tables 1 and 5 for cotton; 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. 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 16 of 28

B.2. Sample Handling and Preparation

At all test sites, one untreated and duplicate treated cotton seed samples were harvested at normal 

harvest at a PHI of 49-105 days for TRT 2 and 6-8 days for TRTs 3-5. Two sites (SC1 and TX1) 

collected additional treated decline samples. The cotton seed samples were harvested by 

mechanical picker, stripper or by hand and ginned to yield ~1.0 kg of undelinted seed samples

(all sites) and ~0.5-1.0 kg of gin byproduct samples (3 sites only). Samples were ginned at the 

field sites within 3 hours after harvest, except for sites OK2, TX2, and TX3 where the cotton was 

ginned 1 day after harvest. The treated samples were placed in frozen storage at the field trials 

within 3.1 hours after sampling. All samples were shipped 0 to 41 days after collection by 

freezer truck or shipped by FedEx overnight to Monsanto (St. Louis, MO) for residue analysis. 

Samples were maintained frozen (-20 °C) at the analytical laboratory prior to homogenization 

and analysis. In preparation for analysis, the cotton gin byproduct samples were initially ground

with dry ice in a vertical cutter/mixer. Undelinted cotton seed and gin byproduct samples were 

further processed by milling in a cryomill, which pulverizes samples into a fine powder at 

cryogenic temperatures. 

B.3. Analytical Methodology

Samples were analyzed for residues of dicamba and the metabolites DCGA, DCSA, and 5-

hydoxy dicamba using a LC/MS/MS method from Monsanto Company: Analytical Method AGME-1381-01. For a complete description of the LC/MS/MS method, refer to the 860.1340 DER 

for MRID 48728702. We note that the analytical method does not specify conversion of 

metabolite residues to parent equivalents; therefore, quantifiable residues of 5-OH dicamba,

DCSA, and DCGA were converted to parent equivalents by the study reviewer using a molecular 

weight conversion factor of 0.933, 1.068, and 0.991, respectively.

Briefly, samples were extracted with acetonitrile:water (40:60, v:v). An aliquot of the extract 

was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate was partitioned with ethyl 

acetate:isooctane (20:80, v:v). Water was added to the organic phase and the sample was 

concentrated by evaporation until only the aqueous solution remained. The samples were 

acidified and analyzed using LC/MS/MS.

The LOQ, determined as the LLMV, was 0.02 ppm for each analyte in undelinted cotton seed 

and 0.04 ppm for each analyte in cotton gin by-products. The 0.020 ppm fortification level was

used to statistically determine the LODs and LOQs for the four analytes of the method in 

undelinted cotton seed. The LODs for the analytes in undelinted cotton seed were 0.0035,

0.0041, 0.0057 and 0.0089 ppm for DCSA, DCGA, 5-hydroxydicamba and dicamba,

respectively. The LOQs for the analytes in undelinted cotton seed were 0.0105, 0.0121, 0.0171

and 0.0266 ppm for DCSA, DCGA, 5-hydroxydicamba and dicamba, respectively (reported as

analyte found per se). The LODs and LOQs were not statistically determined in cotton gin

byproducts.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 17 of 28

The analytical method was validated prior to and in conjunction with the analysis of field trial 

samples. 

C. RESULTS AND DISCUSSION

Sample storage conditions and durations are summarized in Table C.2. Dicamba, 5-OH 

dicamba, and DCSA undelinted cotton seed samples were stored for 13-146 days (0.4-4.8

months) from collection to analysis; DCGA undelinted cotton seed samples were stored for 13-

285 days (0.4-9.4 months). Gin byproduct samples for all analytes were stored from 17-27 days 

(0.6-0.9 months) from collection to analysis. All samples were analyzed within 0 to 2 days of 

extraction. Samples were stored below freezing at the field sites and at -20 °C at the analytical 

laboratory prior to extraction. A storage stability study for dicamba, DCGA, and DCSA on 

cotton was submitted in conjunction with the field trial study (refer to the 860.1380 der for 

MRID 48728704). Residues of dicamba, DCGA, and DCSA were stable during freezer storage 

for up to 277 days (9 months) in undelinted cotton seed. The stability of 5-OH dicamba was not 

determined concurrently because it was not found in undelinted cotton seed. These data are 

acceptable to support the storage conditions and durations of the undelinted cotton seed samples 

from the submitted field trials. Storage stability data is not required for cotton gin byproduct 

samples because the samples were analyzed within 30 days of harvest.

Method validation and concurrent method recovery data are presented in Table C.1. The 

LC/MS/MS method used to analyze cotton samples for residues of dicamba, 5-OH dicamba, 

DCGA, and DCSA was adequate for data collection based on acceptable method and concurrent 

method recovery data. Concurrent recoveries were generally within the acceptable range of 70-

120% in cotton fortified with dicamba, 5-OH dicamba, DCGA, and DCSA each at 0.02-5.00

ppm in undelinted cotton seed and 0.04-100.0 ppm in gin byproducts. The fortification levels 

were adequate to bracket residues found in treated samples. Apparent residues of dicamba, 5-

OH dicamba, DCGA, DSGA were below the LOQ (<0.02 ppm or <0.04 ppm) in/on all samples 

of untreated undelinted cotton seed and cotton gin by-products. Concurrent recoveries were 

corrected for apparent for residues in controls; residues in treated samples were not corrected for 

residues in controls.

Residue data from the cotton field trials are reported in Table C.3. A summary of residue data is 

presented in Table C.4. 

Following three broadcast applications of the 4 lb ae/gal SL formulation of dicamba (formulated 

as the diglycolamine salt), which were applied at pre-emergence, the 6-leaf stage, and first white 

flower + 15 days for a total rate of 2.0 lb ae/A (2.2 kg ae/ha) (TRT 2), combined residues (and 

per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA (expressed in parent 

equivalents) were <0.08-<0.39 (<0.08-<0.39) ppm in/on undelinted cotton seed collected at PHIs 

of 49-105 days and <0.67-<2.34 (<0.73-<2.33) ppm in/on gin byproducts collected at PHIs of 

82-84 days.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 18 of 28

Following three broadcast applications of the 4 lb ae/gal SL formulation of dicamba (formulated 

as the diglycolamine salt), which were applied at pre-emergence, the first open boll stage, and 7 

days prior to harvest for a total rate of 2.0 lb ae/A (2.2 kg ae/ha) (TRT 3), combined residues 

(and per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA (expressed in parent 

equivalents) were <0.12-<2.24 (<0.13-<1.66) ppm in/on undelinted cotton seed collected at a 6-

8-day PHI.

Following four foliar broadcast applications of the 4 lb ae/gal SL formulation of dicamba 

(formulated as the diglycolamine salt), which were applied at the 6-leaf stage, the first white 

flower + 15 days, the first open boll, and 7 days prior to harvest for a total rate of 2.0-2.1 lb ae/A 

(2.2-2.4 kg ae/ha) (TRT 4), combined residues (and per trial averages) of dicamba, 5-OH 

dicamba, DCGA, and DCSA (expressed in parent equivalents) were <0.15-<2.02 (<0.21-<1.86) 

ppm in/on undelinted cotton seed collected at a 6-8-day PHI and <5.50-34.6 (<5.51-<33.7) ppm 

in/on gin byproducts collected at a 6-7-day PHI. Corresponding combined residues (and per trial 

averages) in side-by-side trials treated with the 5 lb ae/gal SL formulation of dicamba formulated 

as the monoethanolamine salt (TRT 5) were <0.24-<1.00 (<0.29-<0.82) ppm in/on undelinted 

cotton seed. Average combined residues in the diglycolamine salt formulation trials were 

slightly higher (approximately 1.5x) than the corresponding residues in the monoethanolamine 

salt formulation trials. 

Treatment plots 3 and 4 showed the highest average combined residues (0.76 ppm), followed 

closely by treatment plot 5 (average of 0.52 ppm). Treatment plot 2 had the lowest average 

combined residues (average of 0.12 ppm). Lower residues from treatment plot 2 is consistent 

with the earlier application timings at these plots. 

For the TRT 2 residue decline samples, average residues of dicamba, 5-OH dicamba, DCGA, 

and DCSA in/on undelinted cotton seed were at or <LOQ in both studies; therefore, residue 

decline could not be assessed. For the TRT 4 residue decline samples, average residues of 

dicamba decreased in/on undelinted cotton seed with increasing PHI. Average residues of 

DCGA and DCSA increased with increasing PHI in the SC1 trial, and remained relatively 

constant in the TX1 trial. Residues of 5-OH dicamba were <LOQ in both studies; therefore, 

residue decline could not be assessed. 

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Method Validation Recoveries

Undelinted 

Cotton seed

Dicamba 0.005 5 187, 73, 172, 105, 102 128 ± 49

0.010 5 129, 149, 93, 78, 125 115 ± 29

0.020 5 119, 100, 123, 101, 124 113 ± 12

0.200 5 94, 96, 95, 97, 100 96.1 ± 2.2

10.0 5 68, 91, 91, 100, 98 89.6 ± 13
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 19 of 28

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Undelinted 

Cotton seed 

(continued)

5-OH 

Dicamba

0.005 5 68, 56, 101, 84, 105 82.9 ± 21

0.010 5 106, 97, 76, 110, 82 94.1 ± 15

0.020 5 96, 98, 115, 117, 114 108 ± 10

0.200 5 98, 104, 105, 104, 101 102 ± 3.0

10.0 5 69, 90, 79, 93, 104 87.1 ± 13

DCGA 0.005 5 140, 115, 88, 98, 129 114 ± 22

0.010 5 90, 108, 96, 79, 104 95.6 ± 11

0.020 5 81, 98, 93, 77, 86 86.9 ± 8.5

0.200 5 90, 87, 88, 84, 96 88.9 ± 4.3

10.0 5 73, 96, 89, 94, 90 88.6 ± 8.9

DCSA 0.005 5 88, 95, 90, 134, 98 101 ± 19

0.010 5 70, 84, 102, 96, 98 89.8 ± 13

0.020 5 100, 82, 97, 97, 95 94.0 ± 6.9

0.200 5 95, 100, 105, 96, 101 98.9 ± 4.0

10.0 5 81, 92, 95, 93, 97 91.6 ± 6.4

Gin 

Byproducts

Dicamba 0.040 5 100, 93, 88, 122, 119 104 ± 15

0.400 5 97, 99, 101, 98, 104 100 ± 2.7

10.0 5 88, 91, 82, 85, 88 86.7 ± 3.1

5-OH 

Dicamba

0.040 5 124, 106, 98, 97, 108 106 ± 11

0.400 5 111, 113, 106, 116, 109 111 ± 3.6

10.0 5 113, 99, 99, 101, 85 99.4 ± 10

DCGA 0.040 5 67, 88, 88, 90, 70 80.4 ± 11

0.400 5 99, 96, 99, 95, 97 97.0 ± 2.0

10.0 5 101, 94, 105, 99, 104 101 ± 4.4

DCSA 0.040 5 79, 87, 76, 75, 81 79.5 ± 4.9

0.400 5 91, 84, 93, 87, 91 89.0 ± 3.7

10.0 5 110, 101, 92, 109, 99 102 ± 7.6

Concurrent Recoveries

Undelinted 

Cotton seed

Dicamba 0.02 19 103, 97.7, 93.5, 104, 104, 98.0, 91.6, 75.5, 96.5, 77.5, 116, 109, 110, 

99.9, 99.7, 103, 108, 119, 110

101 ± 11

0.04 13 105, 106, 84.3, 105, 101, 80.8, 97.6, 119, 114, 110, 100, 108, 109 103 ± 11

0.20 20 94.5, 105, 97.3, 103, 99.9, 107, 103, 98.5, 102, 95.0, 98.0, 108, 93.9, 

97.8, 99.5, 105, 96.5, 101, 105, 94.5

100 ± 4.3

5.00 1 108 108

5-OH 

Dicamba

0.02 13 94.9, 100, 91.0, 79.5, 95.0, 110, 69.5, 68.5, 82.0, 83.0, 88.0, 92.0, 

94.0

88.2 ± 12

0.04 13 93.5, 94.3, 76.5, 86.3, 125, 121, 80.0, 90.3, 105, 110, 109, 107, 92.8 99.3 ± 15

0.20 15 93.2, 97.5, 97.0, 110, 93.9, 83.7, 115, 86.0, 104, 97.0, 93.5, 94.5, 

77.0, 87.5, 108

95.8 ± 10
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 20 of 28

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Undelinted 

Cotton seed 

(continued)

DCGA 0.02 16 83.5, 71.4, 93.0, 86.0, 105, 83.5, 107, 101, 114, 120, 116, 87.5, 79.5, 

95.5, 93.0, 66.9

93.8 ± 16

0.04 12 74.0, 83.9, 90.5, 81.3, 77.5, 101, 88.0, 88.8, 93.0, 79.8, 80.5, 80.3 84.8 ± 7.6

0.20 15 88.0, 92.2, 94.5, 105, 82.5, 86.0, 98.1, 88.0, 90.5, 87.5, 92.5, 77.1, 

96.0, 81.5, 100

90.6 ± 7.5

5.00 1 106 106

DCSA 0.02 18 105, 101, 100, 94.0, 122, 101, 86.0, 101, 91.0, 98.5, 89.5, 98.0, 103, 

106, 101, 92.3, 87.0, 118

99.6 ± 9.4

0.04 13 84.0, 114, 89.3, 96.3, 108, 95.0, 93.8, 103, 106, 102, 103, 108, 106 101 ± 8.5

0.20 17 90.5, 100, 95.0, 107, 102, 97.0, 103, 99.5, 103, 101, 92.3, 100, 105, 

97.2, 98.2, 101, 103

99.7 ± 4.3

5.00 1 99.8 99.8

Gin 

Byproducts

Dicamba 0.04 4 120, 90.5, 88.5, 94.0 98.2 ± 15

0.40 1 97.2 97.2

5.00 3 108, 102, 98.6 103 ± 4.8

100.00 3 96.7, 95.9, 104 98.9 ± 4.5

5-OH 

Dicamba

0.04 4 89.7, 96.7, 107, 98.9 98.0 ± 6.9

0.40 1 103 103

5.00 3 102, 93.3, 87.3 94.1 ± 7.3

100.00 3 111, 94.5, 99.2 102 ± 8.5

DCGA 0.04 4 88.5, 70.0, 93.8, 108 90.1 ± 16

0.40 1 98.0 98.0

5.00 3 110, 98.4, 105 105 ± 5.7

100.00 3 118, 104, 107 110 ± 7.4

DCSA 0.04 4 88.0, 101, 103, 98.0 97.4 ± 6.6

0.40 1 91.0 91.0

5.00 3 125, 114, 123 121 ± 5.9

100.00 3 99.2, 101, 106 102 ± 3.5

1 The concurrent recoveries were corrected for apparent residues in the unfortified control samples.

2

 Standard deviation is not applicable for sample sizes n < 3 samples.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 21 of 28

TABLE C.2. Summary of Storage Conditions.

Matrix Analyte Storage 

Temperature

Actual Storage Duration1Interval of Demonstrated Storage 

Stability2

Undelinted 

Cotton seed

Dicamba Below freezing at 

field sites

-20 oC at analytical 

lab

13-146 days

(0.4-4.8 months)

Residues of dicamba, DCGA, and DCSA 

are stable during freezer storage for up to 

277 days (9 months) in undelinted cotton 

seed. 

The stability of 5-OH dicamba was not 

determined concurrently because it was 

not detected in undelinted cotton seed.

5-OH Dicamba 13-122 days

(0.4-4.0 months)

DCGA 13-285 days

(0.4-9.4 months)

DCSA 13-121 days

(0.4-4.0 months)

Gin 

Byproducts

Dicamba Below freezing at 

field sites

-20 oC at analytical 

lab

17-27 days

(0.6-0.9 months)

Not provided. Storage stability data is not 

required as the samples were analyzed 

5-OH Dicamba within 30 days of harvest.

DCGA

DCSA

1

 Interval from harvest to analysis; all samples were analyzed within 0 to 2 days of extraction.

2 Refer to the 860.1380 der for MRID 48728704. 

TABLE C.3. Residue Data for Dicamba and its Metabolites from Cotton Field Trials 

Trial ID

(City, 

County, 

State; Year)

Zone Commodity1Total 

Rate

lb ae/A

(kg 

ae/ha)

TRT2 PHI

(days)3

Residues (ppm) [Average]4, 5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Proctor, 

Crittenden, 

AR; 2010 

(AR1)

4 Undelinted 

Cotton 

seed

2.0

(2.2)

2 70 (0.01), ND

[<0.02]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.05, 0.04

[0.05]

<0.12, 

<0.11 

[<0.12]

3 7 1.206, 0.596

[0.89]

ND, ND

[<0.02]

0.04, 0.03 

[0.03]

0.10, 0.05 

[0.08]

<1.37, 

<0.69 

[<1.03]

4 7 0.336, 0.586

[0.46]

ND, ND

[<0.02]

0.04, 0.05 

[0.04]

0.05, 0.07 

[0.06]

<0.45, 

<0.72 

[<0.58]

5 7 0.72, 0.51

[0.62]

ND, ND

[<0.02]

0.08, 0.04

[0.06]

0.17, 0.06

[0.12]

<1.00, 

<0.64 

[<0.82]

Porterville, 

Tulare, CA; 

2010 (CA1)

10 Undelinted 

Cotton 

seed

2.0

(2.2)

2 81 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 8 0.18, 0.19

[0.18]

ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 0.02

[<0.02]

<0.24, 

<0.25 

[<0.25]

4 8 0.47, 0.39

[0.43]

ND, ND

[<0.02]

0.04, 

(0.018)

[<0.03]

0.09, 0.04

[0.06]

<0.63, 

<0.47 

[<0.55]

5 8 0.23, 0.17

[0.20]

ND, ND

[<0.02]

0.02, 0.02

[0.02]

0.06, 0.02

[0.04]

<0.34, 

<0.24 

[<0.29]
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 22 of 28

TABLE C.3. Residue Data for Dicamba and its Metabolites from Cotton Field Trials 

Trial ID

(City, 

County, 

State; Year)

Zone Commodity1Total 

Rate

lb ae/A

(kg 

ae/ha)

TRT2 PHI

(days)3

Residues (ppm) [Average]4, 5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Visalia, 

Tulare, CA; 

2010 (CA2)

10 Undelinted 

Cotton 

seed

2.0

(2.2)

2 103 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 8 0.66, 0.64

[0.65]

ND, ND

[<0.02]

ND, (0.01)

[<0.02]

0.02, 0.05

[0.04]

<0.72, 

<0.73 

[<0.73]

4 8 1.05, 0.82

[0.94]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.14, 0.16

[0.15]

<1.25, 

<1.03 

[<1.14]

Chula, Tift, 

GA; 2010 

(GA1)

2 Undelinted 

Cotton 

seed

2.0

(2.2)

2 84 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 7 0.766, 1.306

[0.90]

ND, ND

[<0.02]

(0.01), ND

[<0.02]

(0.016), 

(0.016)

[<0.02]

<0.82, 

<1.36 

[<1.09]

4 7 0.80, 0.71

[0.76]

ND, ND

[<0.02]

0.03, 0.02

[0.03]

0.03, 0.02

[0.02]

<0.88, 

<0.78 

[<0.83]

5 7 0.68, 0.50

[0.59]

ND, ND

[<0.02]

0.02, 

(0.017)

[<0.02]

(0.016), 

(0.016)

[<0.02]

<0.74, 

<0.56 

[<0.65]

Cheneyville, 

Rapides, LA; 

2010 (LA1)

4 Undelinted 

Cotton 

seed

2.0

(2.2)

2 73 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 7 0.33, 0.45

[0.39]

ND, ND

[<0.02]

0.02, 

(0.019)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.39, 

<0.51 

[<0.45]

4 7 0.82, 0.65

[0.74]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.03, 0.06

[0.04]

<0.90, 

<0.76 

[<0.83]

Fisk, Butler, 

MO; 2010 

(MO1)

4 Undelinted 

Cotton 

seed

2.0

(2.2)

2 79 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.015), 

(0.015)

[<0.02]

0.02, 

(0.017)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 7 0.97, 1.00

[0.98]

ND, ND

[<0.02]

(0.019), 

(0.01)

[<0.02]

(0.01), 0.06

[<0.03]

<1.03, 

<1.10 

[<1.07]

4 7 0.566, 1.176

[0.87]

ND, ND

[<0.02]

0.02, 0.02

[0.02]

0.02, 0.03

[0.03]

<0.62, 

<1.25 

[<0.94]
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 23 of 28

TABLE C.3. Residue Data for Dicamba and its Metabolites from Cotton Field Trials 

Trial ID

(City, 

County, 

State; Year)

Zone Commodity1Total 

Rate

lb ae/A

(kg 

ae/ha)

TRT2 PHI

(days)3

Residues (ppm) [Average]4, 5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Hinton, 

Caddo, OK; 

2010 (OK1)

8 Undelinted 

Cotton 

seed

2.0

(2.2)

2 68 ND, ND

[<0.02]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.03, 0.03

[0.03]

<0.10, 

<0.10 

[<0.10]

3 8 0.33, 0.23

[0.28]

ND, ND

[<0.02]

0.05, 0.03

[0.04]

0.08, 0.03

[0.06]

<0.49, 

<0.31 

[<0.40]

4 8 0.356, 0.186

[0.27]

ND, ND

[<0.02]

0.09, 0.05

[0.07]

0.11, 0.07

[0.09]

<0.57, 

<0.33 

[<0.45]

5 8 0.23, 0.23

[0.23]

ND, ND

[<0.02]

0.03, 0.04

[0.04]

0.02, 0.07

[0.04]

<0.30, 

<0.37 

[<0.33]

Dill City, 

Washita, OK; 

2010 (OK2)

8 Undelinted 

Cotton 

seed

2.0

(2.2)

2 82 ND, ND

[<0.02]

ND, ND

[<0.02]

0.03, 0.02

[0.03]

0.03, (0.01)

[<0.02]

<0.10, 

<0.08 

[<0.09]

3 7 0.07, 0.06

[0.06]

ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.13, 

<0.12 

[<0.13]

4 7 0.12, 0.16

[0.14]

ND, ND

[<0.02]

0.02, 0.03

[0.03]

0.03, 0.03

[0.03]

<0.19, 

<0.24 

[<0.22]

Gin 

byproducts

2 82 ND, ND

[<0.04]

(0.01), 

(0.01)

[<0.04]

0.17, 0.23

[0.20]

0.39, 0.46

[0.43]

<0.67, 

<0.80 

[<0.73]

4 7 3.17, 3.09

[3.13]

(0.01), 

(0.01)

[<0.04]

0.49, 0.40

[0.45]

1.70, 1.85

[1.78]

<5.52, 

<5.50 

[<5.51]

Elko, 

Barnwell, 

SC; 2010 

(SC1)

2 Undelinted 

Cotton 

seed

2.0

(2.2)

2 99 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

105 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

112 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

119 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 7 0.18, 0.06

[0.12]

ND, ND

[<0.02]

ND, 0.02

[<0.02]

(0.01), 0.02

[<0.02]

<0.24, 

<0.12 

[<0.18]

4 1 0.21, 0.31

[0.26]

ND, ND

[<0.02]

0.02, 0.03

[0.03]

0.02, 0.03

[0.03]

<0.28, 

<0.39 

[<0.34]

7 0.14, 0.09

[0.12]

ND, ND

[<0.02]

0.06, 

(0.018)

[<0.04]

0.05, 0.02

[0.04]

<0.27, 

<0.15 

[<0.21]
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 24 of 28

TABLE C.3. Residue Data for Dicamba and its Metabolites from Cotton Field Trials 

Trial ID

(City, 

County, 

State; Year)

Zone Commodity1Total 

Rate

lb ae/A

(kg 

ae/ha)

TRT2 PHI

(days)3

Residues (ppm) [Average]4, 5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

14 0.09, 0.07

[0.08]

ND, ND

[<0.02]

0.107, 0.05

7

[0.05]

0.06, 0.03

[0.05]

<0.28, 

<0.17 

[<0.22]

21 0.04, 0.08

[0.06]

ND, ND

[<0.02]

0.117, 0.04

7

[0.06]

0.09, 0.03

[0.06]

<0.26, 

<0.17 

[<0.22]

Raymondvill

e, Willacy, 

TX; 2010 

(TX1)

6 Undelinted 

Cotton 

seed

2.0

(2.2)

2 43 ND, ND

[<0.02]

ND, ND

[<0.02]

0.02,

(0.019)

[<0.02]

0.03, (0.01)

[<0.02]

<0.09, 

<0.08 

[<0.09]

49 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 0.02

[<0.02]

0.02, (0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

56 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.019)

[<0.02]

(0.01), 0.03

[<0.02]

<0.08, 

<0.09 

[<0.08]

63 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.018), 

(0.01)

[<0.02]

(0.016), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 7 0.586, 0.196

[0.38]

ND, ND

[<0.02]

ND, ND

[<0.02]

0.07, (0.01)

[<0.04]

<0.70, 

<0.25 

[<0.48]

6 Undelinted

Cotton 

seed

2.1

(2.4)

4 1 0.28, 0.23

[0.25]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.03, 0.03

[0.03]

<0.36, 

<0.31 

[<0.33]

7 0.19, 0.17

[0.18]

ND, ND

[<0.02]

0.03, 0.02

[0.03]

0.09, 0.04

[0.06]

<0.34, 

<0.25 

[<0.29]

14 0.07, 0.04

[0.05]

ND, ND

[<0.02]

0.03, 0.02

[0.03]

0.04, 0.03

[0.04]

<0.17, 

<0.11 

[<0.14]

21 0.03, 0.04

[0.03]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.03, 0.03

[0.03]

<0.12, 

<0.13 

[<0.12]

Levelland, 

Hockley, TX; 

2010 (TX2)

8 Undelinted 

Cotton 

seed

2.0

(2.2)

2 84 ND, ND

[<0.02]

ND, ND

[<0.02]

0.11, 0.11

[0.11]

0.23, 0.23

[0.23]

<0.39, 

<0.39 

[<0.39]

3 6 0.846, 1.316

[1.07]

(0.01), ND

[<0.02]

0.07, 0.05

[0.06]

0.076, 0.256

[0.16]

<1.00, 

<1.64 

[<1.32]

4 6 1.30, 1.54

[1.42]

ND, (0.01)

[<0.02]

0.11, 0.17

[0.14]

0.26, 0.27

[0.27]

<1.71, 

<2.02 

[<1.86]

Gin 

byproducts

2 84 ND, (0.01)

[<0.04]

ND, (0.01)

[<0.04]

0.42, 0.71

[0.57]

1.73, 1.43

[1.58]

<2.34, 

<2.31 

[<2.33]

4 6 16.4, 13.4

[14.9]

0.04, (0.03)

[<0.04]

3.25, 1.56

[2.41]

6.02, 2.97

[4.50]

<26.1, 

<18.2 

[<22.1]
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 25 of 28

TABLE C.3. Residue Data for Dicamba and its Metabolites from Cotton Field Trials 

Trial ID

(City, 

County, 

State; Year)

Zone Commodity1Total 

Rate

lb ae/A

(kg 

ae/ha)

TRT2 PHI

(days)3

Residues (ppm) [Average]4, 5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Wolfforth, 

Lubbock, 

TX; 2010 

(TX3)

8 Undelinted 

Cotton 

seed

2.0

(2.2)

2 84 ND, ND

[<0.02]

ND, ND

[<0.02]

0.07, 0.04

[0.05]

0.10, 0.04

[0.07]

<0.22, 

<0.12 

[<0.17]

3 6 1.976, 0.806

[1.38]

(0.01), ND

[<0.02]

0.07, 0.10

[0.09]

0.16, 0.16

[0.16]

<2.24, 

<1.09 

[<1.66]

4 6 1.29, 1.08

[1.19]

ND, ND

[<0.02]

0.08, 0.12

[0.10]

0.11, 0.16

[0.14]

<1.51, 

<1.39 

[<1.45]

Gin 

byproducts

2 84 ND, ND

[<0.04]

(0.01), 

(0.01)

[<0.04]

0.32, 0.31

[0.32]

0.85, 0.49

[0.67]

<1.30, 

<0.91 

[<1.11]

4 6 23.6, 22.4

[23.0]

(0.03), 

(0.03)

[<0.04]

4.31, 3.97

[4.14]

6.29, 6.05

[6.17]

<34.6, 

<32.8 

[<33.7]

Uvalde, 

Uvalde, TX; 

2010 (TX4)

8 Undelinted 

Cotton 

seed

2.0

(2.2)

2 71 ND, ND

[<0.02]

ND, ND

[<0.02]

(0.01), 

(0.01)

[<0.02]

(0.01), 

(0.01)

[<0.02]

<0.08, 

<0.08 

[<0.08]

3 6 0.86, 1.22

[1.04]

ND, (0.016)

[<0.02]

0.02, 0.03

[0.03]

0.03, 0.04

[0.03]

<0.93, 

<1.31 

[<1.12]

4 6 0.49, 0.44

[0.47]

ND, ND

[<0.02]

0.03, 0.03

[0.03]

0.03, 0.04

[0.04]

<0.58, 

<0.53 

[<0.55]

1 Each trial site was planted with Event MON 88701 cotton that is tolerant to dicamba herbicide and glufosinate-ammonium 

herbicide.

2 TRT 2: Applications with 4 lb ae/gal SL formulation made at preemergence, the 6-leaf stage, and at the first white flower + 15 

days stage; TRT 3: Applications with 4 lb ae/gal SL formulation made at preemergence, the first open boll stage, and at 7 days 

prior to harvest; TRT 4: Applications with 4 lb ae/gal SL formulation made at the 6-leaf stage, the first white flower + 15-days 

stage, the first open boll stage, and at 7 days prior to harvest; TRT 5: Applications with 5 lb ae/gal SL formulation made at the 6-

leaf stage, the first white flower + 15-days stage, the first open boll stage, and at 7 days prior to harvest.

3 For the residue decline trials, the target PHI is bolded.

4 ND = <LOD. The LODs for the analytes in undelinted cotton seed were 0.0035, 0.0041, 0.0057 and 0.0089 ppm for

DCSA, DCGA, 5-hydroxydicamba and dicamba, respectively. The LOQ was 0.02 ppm for each analyte in undelinted cotton 

seed and 0.04 ppm in cotton gin byproducts. Values between the LOQ and LOD are in parenthesis.

5 Residues for individual analytes are presented as per se. Combined residues of dicamba, 5-OH dicamba, DCGA, and DCSA 

are expressed in parent equivalents. Residues of 5-OH dicamba, DCSA, and DCGA were converted to parent equivalents by the 

study reviewer using molecular weight conversion factors of 0.933, 1.068, and 0.991, respectively. When calculating per trial 

averages, the LOQ was used for values reported as ND or between the LOD and LOQ. NOTE TO EPA REVIEWER: DCGA 

is included in the combined residues as it is a major metabolite of dicamba.

6 Average of multiple analyses.

7 The data in Table 13 (p. 53) does not match the raw data in the Master Summary Table (p. 361). It appears that the DCGA data 

in Table 13 was copied from the DCSA data. The study reviewer used the raw data for DCGA.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 26 of 28

TABLE C.4. Summary of Residue Data from Cotton Crop Field Trials with Dicamba.

Commodity Analyte Total App.

Rate

lb ae/A

(kg ae/ha)

PHI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

TRT 2 (Applications at Preemergence, 6-leaf stage, and first white flower + 15 days; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

49-105 13 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

5-OH Dicamba 13 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

DCGA 13 <0.02 0.11 <0.02 0.11 0.02 0.03 0.03

DCSA 13 <0.02 0.23 <0.02 0.23 0.02 0.04 0.06

Combined 

Residues

13 <0.08 <0.39 <0.08 <0.39 0.08 0.12 0.09

Gin 

byproducts

Dicamba 2.0

(2.2)

82-84 3 <0.04 <0.04 <0.04 <0.04 0.04 0.04 N/A

5-OH Dicamba 3 <0.04 <0.04 <0.04 <0.04 0.04 0.04 N/A

DCGA 3 0.17 0.71 0.20 0.57 0.32 0.36 0.19

DCSA 3 0.39 1.73 0.43 1.58 0.67 0.89 0.61

Combined 

Residues

3 <0.67 <2.34 <0.73 <2.33 1.11 1.39 0.84

TRT 3 (Applications at Preemergence, first open boll stage, and 7 days prior to harvest; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

6-8 13 0.06 1.97 0.06 1.38 0.65 0.64 0.43

5-OH Dicamba 13 <0.02 0.02 <0.02 <0.02 0.02 0.02 N/A

DCGA 13 <0.02 0.10 <0.02 0.09 0.02 0.03 0.02

DCSA 13 <0.02 0.25 <0.02 0.16 0.03 0.05 0.05

Combined 

Residues

13 <0.12 <2.24 <0.13 <1.66 0.73 0.76 0.49

TRT 4 (Applications at 6-leaf, first white flower + 15 days, first open boll, and 7 days prior to harvest; EP: Clarity)

Undelinted 

Cotton seed

Dicamba 2.0-2.1

(2.2-2.4)

6-8 13 0.09 1.54 0.12 1.42 0.47 0.61 0.41

5-OH Dicamba 13 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 N/A

DCGA 13 0.02 0.17 0.02 0.14 0.03 0.05 0.04

DCSA 13 0.02 0.27 0.02 0.27 0.06 0.08 0.07

Combined 

Residues

13 <0.15 <2.02 <0.21 <1.86 0.58 0.76 0.49

Gin 

byproducts

Dicamba 2.0

(2.2)

6-7 3 3.09 23.6 3.13 23.0 14.9 13.7 10.0

5-OH Dicamba 3 <0.04 0.04 <0.04 <0.04 0.04 0.04 N/A

DCGA 3 0.40 4.31 0.45 4.14 2.41 2.33 1.85

DCSA 3 1.70 6.29 1.78 6.17 4.50 4.15 2.22

Combined 

Residues

3 <5.50 34.6 <5.51 <33.7 22.1 20.4 14.2

TRT 5 (Applications at 6-leaf, first white flower + 15 days, first open boll, and 7 days prior to harvest; EP: MON 11968)

Undelinted 

Cotton seed

Dicamba 2.0

(2.2)

7-8 4 0.17 0.72 0.20 0.62 0.41 0.41 0.23

5-OH Dicamba 4 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

DCGA 4 0.02 0.08 0.02 0.06 0.03 0.04 0.02

DCSA 4 0.02 0.17 0.02 0.12 0.04 0.06 0.04

Combined 

Residues

4 <0.24 <1.00 <0.29 <0.82 0.49 0.52 0.26

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 (0.02 ppm each analyte in undelinted cotton seed and 0.04 ppm for each analyte in cotton gin 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 27 of 28

byproducts) was used for any results reported as <LOQ in Table C.3. Combined residues of dicamba, 5-OH dicamba, DCGA, 

and DCSA are expressed in parent equivalents. Individual analyte results are reported as per se. NOTE TO EPA REVIEWER: 

DCGA is included in the combined residues as it is a major metabolite of dicamba.

N/A = Not applicable.

2

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

D. CONCLUSION

The submitted cotton field trial data are adequate and reflect the use of three to four broadcast 

applications of the 4 lb ae/gal SL formulation of dicamba (formulated as the diglycolamine salt), 

at a total rate of 2.0-2.1 lb ae/A (2.2-2.4 kg ae/ha). Following three applications at preemergence, the 6-leaf stage, and first white flower + 15 days (TRT2), combined residues (and 

per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA (expressed in parent 

equivalents) were <0.08-<0.39 (<0.08-<0.39) ppm in/on undelinted cotton seed collected at PHIs 

of 49-105 days and <0.67-<2.34 (<0.73-<2.33) ppm in/on gin byproducts collected at PHIs of 

82-84 days. Following three applications at pre-emergence, the first open boll stage, and 7 days 

prior to harvest (TRT 3) combined residues (and per trial averages) of dicamba, 5-OH dicamba, 

DCGA, and DCSA (expressed in parent equivalents) were <0.12-<2.24 (<0.13-<1.66) ppm in/on 

undelinted cotton seed collected at a 6-8-day PHI. Following four applications at the 6-leaf 

stage, the first white flower + 15 days, the first open boll, and 7 days prior to harvest (TRT 4), 

combined residues (and per trial averages) of dicamba, 5-OH dicamba, DCGA, and DCSA

(expressed in parent equivalents) were <0.15-<2.02 (<0.21-<1.86) ppm in/on undelinted cotton 

seed collected at a 6-8-day PHI and <5.50-34.6 (<5.51-<33.7) ppm in/on gin byproducts

collected at a 6-7-day PHI. Corresponding combined residues (and per trial averages) in side-byside trials treated with the 5 lb ae/gal SL formulation of dicamba formulated as the 

monoethanolamine salt (TRT 5) were <0.24-<1.00 (<0.29-<0.82) ppm in/on undelinted cotton 

seed. Average combined residues in the diglycolamine salt formulation trials were slightly 

higher (approximately 1.5x) than the corresponding residues in the monoethanolamine salt 

formulation trials. 

Treatment plots 3 and 4 showed the highest average combined residues (0.76 ppm), followed 

closely by treatment plot 5 (average of 0.52 ppm). Treatment plot 2 had the lowest average 

combined residues (average of 0.12 ppm). Lower residues from treatment plot 2 is consistent 

with the earlier application timings at these plots. 

For the TRT 2 residue decline samples, average residues of dicamba, 5-OH dicamba, DCGA, 

and DCSA in/on undelinted cotton seed were at or <LOQ in both studies; therefore, residue 

decline could not be assessed. For the TRT 4 residue decline samples, average residues of 

dicamba decreased in/on undelinted cotton seed with increasing PHI. Average residues of

DCGA and DCSA increased with increasing PHI in the SC1 trial, and remained relatively 

constant in the TX1 trial. Residues of 5-OH dicamba were <LOQ in both studies; therefore, 

residue decline could not be assessed. 

An acceptable method was used for residue quantitation, and adequate data were submitted to 

support sample storage intervals and conditions.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3

Crop Field Trial/ Residue Decline – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 28 of 28

E. REFERENCES

None.

F. DOCUMENT TRACKING

Petition Number(s): 2F8067

DP Barcode(s): 408384

PC Code: 029801, 029802, 029806, 128931, 128944, & 129043

Template Version June 2005.
Dicamba/MON 11900/PC Code 12893 1/Monsanto Company 

DACO 7.4.5/0PPTS 860.1520/0ECD llA 6.5.4 and lllA 8.5 

Processed Food and Feed - Dicamba-Tolerant Cotton (Event MON 88701) 

Primary Evaluator 

Versar, Inc. 

- ;;f 

Approved by ( J,-r;-v- 4a.~<-~ Peter Savoia, Chemist, OCSPP-HED-RAB VNH 

Date: 11/15/2012 

Date: 04/22/2013 

Note: This DER was originally prepared under contract by Versar. Inc. (6850 Versar Center. Springfield. V /\ 22151: submitted 

I 1/15112). The DER has been reviewed by the Health Elkcts Division (I JED) and revised to renect current Office of Pesticide 

Programs (OPP) policies. 

STUDY REPORTS: 

48728703 Maher, D. ; Foster. J. (201 1) Magnitude of Oicamba Residues in Cotton Raw 

Agricultural and Processed Commodities following Applications of Dicamba-Based 

Formulations to MON 8870 l. Project Number: REG/I 0/062/0CR, MSL0024072. Unpublished 

study prepared by Monsanto Company, Carringers, Inc. and GLP Technologies. 603 p. 

EXECUTIVE SUMMARY: 

Monsanto has submitted a processing study for dicamba on dicamba-tolerant cotton, identified as 

Event MON 88701 (formerly GH_S26695). Event MON 88701 cotton expresses a modified 

dicamba mono-oxygenase (DMO) gene derived from Stenotrophomonas maltophilia and the 

bialaphos resistance (BAR) gene isolated from Streptomyces hygroscopicus. The expression of 

DMO confers dicamba tolerance and the expression of BAR confers glufosinate tolerance to 

Event MON 8870 l cotton. Two trials were conducted in MO and TX during the 20 I 0 growing 

season. 

Each trial contained two treated plots that fo llowed one of two treatment types: three broadcast 

appli cations applied at pre-emergence, 6-leaf, and pt white flower + 15 days [TRT 2] or four 

foliar broadcast applications applied at 6-leaf, l 51 white flower + 15 days, first open boll, and 7 

days prior to harvest (TRT 4]. Applications were made at the field rate using a 4 lb ae/gal wacer 

soluble concentrate (SL) formulation of dicamba diglycolamine salt (Clarity Herbicide; MON 

54140). The total application rate for both treatment types was 2.0 lb ae/ A (2.2 kg ae/ha). 

For TRT 2, application l was applied at 1.0 lb ae/A ( 1.1 kg ae/ha) and applications 2 and 3 were 

applied at 0.50 lb ae/A/application (0.56 kg ae/ha/applicacion). Retreatment intervals (RTis) 

were 24-49 days between the first and second applications and 42-47 days between the second 

and third applications. For TRT 4, all four applications were applied at 0.49-0.51 lb 

ae/A/application (0.55-0.57 kg ae/ha/application). RTis were 42-47 days between the first and 

second applications, 36-42 days between the second and third applications. and 29-30 days 

between the third and fourth applications. 

All applications were made using ground equipment in spray volumes of 19. 7-20.5 gal/ A (184-

192 I/ha) and included a nonionic surfactant (NIS) and ammonium sulfate (AMS) at all trial sites. 

Samples of undelinted cotton seed were harvested using a mechanical picker at maturity 

(preharvest interva l [PHI] of 7 I -79 days for TRT 2 and 6-7 days for TRT 4 ). Samples of cotton 

0408384/MRJD No. 48728703 Page I of 15 
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 2 of 15

seed were processed into meal, hulls, alkali-refined oil, and RBD oil by GLP Technologies 

(Navasota, TX) using procedures simulating commercial processing.

Samples were analyzed for residues of dicamba and metabolites 5-hydroxydicamba (5-OH 

dicamba), 3,6-dichlorosalicylic acid (DCSA), and 3,6-dichlorogentisic acid (DCGA) using a high 

performance liquid chromatography method with tandem mass spectrometry detection

(LC/MS/MS). The limit of quantitation (LOQ, equivalent to the lowest level of method 

validation; LLMV) was 0.02 ppm for all analytes in undelinted cotton seed (RAC) and the 

processed commodities. The method was adequate for data validation based on acceptable 

method and concurrent recovery data. The fortification levels used in concurrent method 

recovery were adequate to bracket expected residue levels. Concurrent recoveries were 

corrected for apparent residues in controls; residues in treated samples were not corrected for 

residues in controls. We note that the analytical method does not specify conversion of 

metabolite residues to parent equivalents; therefore, quantifiable residues of 5-OH dicamba, 

DCSA, and DCGA were converted to parent equivalents by the study reviewer using a molecular 

weight conversion factor of 0.933, 1.068, and 0.991, respectively.

Samples were stored frozen (~-20 °C) from harvest/processing to analysis for 152-196 days (5.0-

6.4 months) for cotton (RAC) and 19-40 days (0.6-1.3 months) for the processed commodities. 

All samples were analyzed on the day of extraction. Processing took place within 118-169 days

of harvest. A storage stability study for dicamba, DCGA, and DCSA on undelinted cotton seed 

was submitted in conjunction with the field trial study (refer to the 860.1380 der for MRID 

48728704). The stability of 5-OH dicamba was not determined concurrently because it was not 

found in undelinted cotton seed. These data are acceptable to support the storage conditions and 

durations of the undelinted cotton seed samples from the submitted field trials. Storage stability 

data for the processed commodities was not provided; however, storage stability data is not 

required as the processed commodities were generally analyzed within 30 days of processing.

Following three or four applications of the 4 lb ae/gal SC formulation at a total rate of 2 lb ae/A

(2.2 kg ae/ha), using PHIs of 71-79 days and 6-7 days, respectively, the combined residues of 

dicamba, 5-OH dicamba, DCGA, and DCSA (in parent equivalents) were below the LOQ 

(<0.08)-<0.78 ppm in/on undelinted cotton seed (RAC), <0.081-<0.79 ppm in hulls, below the 

LOQ (<0.08)-<0.28 ppm in meal, and below the LOQ (<0.08 ppm) in alkali refined oil and RBD 

oil. 

The processing data indicate that the combined residues do not concentrate in hulls, meal, alkali 

refined oil, or RBD oil (average processing factors of 0.86x, 0.49, 0.11x, and 0.11x, 

respectively). 

The processing factors calculated in this study for combined residues of dicamba, 5-OH 

dicamba, DCGA, and DCSA in cotton were less than the theoretical concentration factor of 3.8x 

for hulls, 2.2x for meal, and 6.3x for oil (based separation of components; OPPTS 860.1520, 

Table 3).
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 3 of 15

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document D408384.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance, and Data Confidentiality 

statements were provided. No deviations from regulatory requirements were reported which 

would have an impact on the validity of the study.

A. BACKGROUND INFORMATION

Dicamba (3,6-dichloro-2-methoxybenzoic acid is a selective benzoic acid herbicide registered 

for the control of weeds prior to their emergence. The Dicamba Reregistration Eligibility 

Decision (RED) was issued December 2005. The chemical structure and nomenclature of 

dicamba and its metabolites 5-OH dicamba, DSCA, and DCGA are presented in Table A.1. The 

physicochemical properties of the technical grade of dicamba acid are presented in Table A.2. 

TABLE A.1. Test Compound Nomenclature.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Clarity® Herbicide: SL formulation containing 4 lb ae/gal

Compound

Common name 5-Hydroxy-dicamba

Company experimental name 5-OH dicamba

IUPAC/CAS name 2,5-dichloro-3-hydroxy-6-methoxybenzoic acid

CAS registry number 7600-50-2
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 4 of 15

TABLE A.1. Test Compound Nomenclature.

Compound

Common name DCSA; 3,6-dichlorosalicylic acid

Company experimental name MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7

Compound

Common name DCGA; 3,6-dichlorogentistic acid

Company experimental name MON 52724

IUPAC/CAS name 2,5-dichloro-3,6-dihydroxybenzoic acid

CAS registry number 18688-01-2

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED, DP# 317699, 12/20/05, 

C. Olinger pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 5 of 15

B. EXPERIMENTAL DESIGN

B.1. Application and Crop Information

In two crop field trials conducted in MO and TX, one untreated and two treated plots were 

planted with dicamba-tolerant cotton (Event MON 88701) containing a dicamba monooxygenase (DMO) gene to confer tolerance to dicamba and a bialophos resistance (BAR) gene to 

confer tolerance to the glufosinate. Each treated plot followed one of two treatment types: three 

broadcast applications applied at pre-emergence, 6-leaf, and 1st white flower + 15 days [TRT 2] 

or four foliar broadcast applications applied at 6-leaf, 1st white flower + 15 days, first open boll, 

and 7 days prior to harvest [TRT 4]. Applications were made at the field rate using a 4 lb ae/gal 

SL formulation of dicamba diglycolamine salt (Clarity Herbicide; MON 54140). The total 

application rate for both treatment types was 2.0 lb ae/A (2.2 kg ae/ha). For TRT 2, application 1 

was applied at 1.0 lb ae/A (1.1 kg ae/ha) and applications 2 and 3 were applied at 0.50 lb 

ae/A/application (0.56 kg ae/ha/application). RTIs were 24-49 days between the first and second 

applications and 42-47 days between the second and third applications. For TRT 4, all four 

applications were applied at 0.49-0.51 lb ae/A/application (0.55-0.57 kg ae/ha/application). RTIs

were 42-47 days between the first and second applications, 36-42 days between the second and 

third applications, and 29-30 days between the third and fourth applications. 

All applications were made using ground equipment in spray volumes of 19.7-20.5 gal/A (184-

192 l/ha) and included an NIS and an AMS at all trial sites. Samples of undelinted cotton seed

were harvested using a mechanical picker at maturity (PHI of 71-79 days for TRT2 and 6-7 days 

for TRT4). Study use pattern data are reported in Table B.1.

TABLE B.1. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb ae/A

(kg ae/A)

RTI2

(days)

Total 

Rate

lb ae/A

(kg ae/A)

Fisk, Butler, 

MO; 2010 

(MO1)

4 lb 

ae/gal 

SL

2 1. Broadcast; Preemergence 20.0

(187)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

29

3. Foliar broadcast; 1st WF

+ 15 days

20.0

(187)

0.50

(0.56)

42

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.3

(190)

0.51

(0.57)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF 

+ 15 days

20.1

(188)

0.50

(0.56)

42

3. Foliar broadcast; 1st open 

boll

20.0

(187)

0.50

(0.56)

42

4. Foliar broadcast; 7 days 

prior to harvest

20.0

(187)

0.50

(0.56)

30
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 6 of 15

TABLE B.1. Study Use Pattern.

Location

City, County, 

State;Year 

(Trial ID)

EP1 TRT Application Tank Mix/ 

Adjuvants3

Harvest 

Method; Timing Volume Procedures

gal/A

(l/ha)

Rate 

lb ae/A

(kg ae/A)

RTI2

(days)

Total 

Rate

lb ae/A

(kg ae/A)

Uvalde, 

Uvalde, TX; 

2010 (TX4)

4 lb 

ae/gal 

SL

2 1. Broadcast; Preemergence 20.2

(189)

1.0

(1.1)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 6-leaf 20.1

(188)

0.50

(0.56)

49

3. Foliar broadcast; 1st WF 

+ 15 days

19.9

(186)

0.50

(0.56)

47

4 lb 

ae/gal 

SL

4 1. Foliar broadcast; 6-leaf 20.0

(187)

0.50

(0.56)

-- 2.0

(2.2)

NIS + AMS Mechanical 

picker

2. Foliar broadcast; 1st WF 

+ 15 days

19.7

(184)

0.49

(0.55)

47

3. Foliar broadcast; 1st open 

boll

20.5

(192)

0.49

(0.55)

36

4. Foliar broadcast; 7 days 

prior to harvest

20.2

(189)

0.51

(0.57)

29

1 EP = End-use Product; Clarity [water soluble concentrate (SL) formulation containing 480 g/L dicamba formulated as the 

diglycolamine salt (4 lb ae/gal)].

2 Retreatment Interval.

3 NIS = nonionic surfactant. AMS = ammonium sulfate.

B.2. Sample Handling and Processing Procedures

Single bulk samples of undelinted cotton seed (~19-32 kg) from the control and treated plots 

were collected and ginned at the field sites within 3 hours of harvest. Samples were placed in 

frozen storage within 1.0 hour of collection. The samples were stored frozen for 5-25 days after

collection then shipped frozen via freezer truck to the processing facility, GLP Technologies 

(Navasota, TX). Cotton seed samples were stored frozen (~<-12 °C) at GLP Technologies until 

processing and were processed within 118-169 days of harvest. Samples from both trials were 

processed into meal, hulls, alkali-refined oil, and RBD oil using procedures simulating 

commercial processing. Samples were stored frozen after processing and were shipped frozen 

within 6-20 days after processing via FedEx to Monsanto Company (St. Louis, MO) for residue 

analysis. Samples were maintained frozen (~-20 °C) at the analytical laboratory. In preparation 

for analysis, samples (except oil) were milled in a cryomill, which pulverizes samples into a fine 

powder at cryogenic temperatures. 

The petitioner submitted adequate descriptions of the processing procedures including material 

balance summaries. The cotton processing procedure is summarized below in Figure 1, which 

was copied without alteration from MRID 48728703.
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 7 of 15

FIGURE 1. Processing Flowchart for Cotton.
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 8 of 15

B.3. Analytical Methodology

Samples were analyzed for residues of dicamba and the metabolites DCGA, DCSA, and 5-

hydoxy dicamba using a LC/MS/MS method from Monsanto Company: Analytical Method AGME-1381-01. For a complete description of the LC/MS/MS method, refer to the 860.1340 DER 

for MRID 48728702. We note that the analytical method does not specify conversion of 

metabolite residues to parent equivalents; therefore, quantifiable residues of 5-OH dicamba, 

DCSA, and DCGA were converted to parent equivalents by the study reviewer using molecular 

weight conversion factors of 0.933, 1.068, and 0.991, respectively.

Briefly, samples were extracted with acetonitrile:water (40:60, v:v). An aliquot of the extract 

was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate was partitioned with ethyl 

acetate:isooctane (20:80, v:v). Water was added to the organic phase and the sample was 

concentrated by evaporation until only the aqueous solution remained. The samples were 

acidified and analyzed using LC/MS/MS.

The LOQ, determined as the LLMV, was 0.02 ppm for each analyte in each cotton matrix. The

0.020 ppm fortification level was used to statistically determine the LODs and LOQs for the

four analytes of the method in undelinted cotton seed (RAC). The LODs for the analytes in

undelinted cotton seed were 0.0035, 0.0041, 0.0057 and 0.0089 ppm for DCSA, DCGA, 5-

hydroxydicamba and dicamba, respectively. The LOQs for the analytes in undelinted cotton

seed were 0.0105, 0.0121, 0.0171 and 0.0266 ppm for DCSA, DCGA, 5-hydroxydicamba and

dicamba, respectively (reported as analyte found per se). The LODs and LOQs were not

statistically determined in the processed fractions.

The analytical method was validated prior to and in conjunction with the analysis of the 

submitted samples. 

C. RESULTS AND DISCUSSION

Sample storage conditions and durations for samples of cotton and processed commodities are 

reported in Table C.2. Samples were stored under frozen (-20 °C) at the analytical laboratory 

from harvest/processing to analysis. Processing took place within 118-169 days of harvest. 

Sample analyses were completed within 152-196 days (5.0-6.4 months) for cotton (RAC) and 

19-40 days (0.6-1.3 months) for processed commodities. All samples were analyzed on the day 

of extraction. A storage stability study for dicamba, DCGA, and DCSA on cotton was submitted 

in conjunction with the field trial study (refer to the 860.1380 der for MRID 48728704). 

Residues of dicamba, DCGA, and DCSA were stable during freezer storage for up to 277 days (9 

months) in undelinted cotton seed. The stability of 5-OH dicamba was not determined 

concurrently because it was not found in undelinted cotton seed. These data are acceptable to 

support the storage conditions and durations of the undelinted cotton seed samples from the 

submitted field trials. Storage stability data for the processed commodities was not provided; 

however, storage stability data is not required as the processed commodities were generally 

analyzed within 30 days of processing.
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 9 of 15

Method validation and concurrent method recovery data for the LC/MS/MS method are 

presented in Table C.1. The LC/MS/MS method used to analyze cotton samples for residues of 

dicamba, 5-OH dicamba, DCGA, and DCSA was adequate for data collection based on 

acceptable method and concurrent method recovery data. Concurrent recoveries were generally 

within the acceptable range of 70-120% in cotton and processed commodity samples fortified 

with dicamba, 5-OH dicamba, DCGA, and DCSA each at 0.02-0.200 ppm. The fortification 

levels were adequate to bracket residues found in treated samples. Apparent residues of 

dicamba, 5-OH dicamba, DCGA, DSGA were below the LOQ (<0.02 ppm) in/on all samples of 

untreated undelinted cotton seed (RAC), hulls, meal, alkali refined oil, and RBD oil. Concurrent 

recoveries were corrected for apparent for residues in controls; residues in treated samples were 

not corrected for residues in controls.

Residue data from the cotton processing study are reported in Table C.3. Following three or four 

applications of the 4 lb ae/gal SC formulation at a total rate of 2 lb ae/A, using PHIs of 71-79 

days and 6-7 days, respectively, the combined residues of dicamba, 5-OH dicamba, DCGA, and 

DCSA (in parent equivalents) were below the LOQ (<0.08)-<0.78 ppm in/on undelinted cotton 

seed (RAC), <0.081-<0.79 ppm in hulls, below the LOQ (<0.08)-<0.28 ppm in meal, and below 

the LOQ (<0.08 ppm) in alkali refined oil and RBD oil. 

The processing data indicate that the combined residues do not concentrate in hulls, meal, alkali 

refined oil, or RBD oil (average processing factors of 0.86x, 0.49, 0.11x, and 0.11x, 

respectively). 

The processing factors calculated in this study for combined residues of dicamba, 5-OH 

dicamba, DCGA, and DCSA in cotton were less than the theoretical concentration factor of 3.8x 

for hulls, 2.2x for meal, and 6.3x for oil (based separation of components; OPPTS 860.1520, 

Table 3).

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton Matrices

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Method Validation Recoveries

Undelinted 

Cotton seed 

(RAC)3

Dicamba 0.005 5 187, 73, 172, 105, 102 128 ± 49

0.010 5 129, 149, 93, 78, 125 115 ± 29

0.020 5 119, 100, 123, 101, 124 113 ± 12

0.200 5 94, 96, 95, 97, 100 96.1 ± 2.2

10.0 5 68, 91, 91, 100, 98 89.6 ± 13
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 10 of 15

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton Matrices

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Undelinted 

Cotton seed 

(continued)

5-OH 

Dicamba

0.005 5 68, 56, 101, 84, 105 82.9 ± 21

0.010 5 106, 97, 76, 110, 82 94.1 ± 15

0.020 5 96, 98, 115, 117, 114 108 ± 10

0.200 5 98, 104, 105, 104, 101 102 ± 3.0

10.0 5 69, 90, 79, 93, 104 87.1 ± 13

DCGA 0.005 5 140, 115, 88, 98, 129 114 ± 22

0.010 5 90, 108, 96, 79, 104 95.6 ± 11

0.020 5 81, 98, 93, 77, 86 86.9 ± 8.5

0.200 5 90, 87, 88, 84, 96 88.9 ± 4.3

10.0 5 73, 96, 89, 94, 90 88.6 ± 8.9

DCSA 0.005 5 88, 95, 90, 134, 98 101 ± 19

0.010 5 70, 84, 102, 96, 98 89.8 ± 13

0.020 5 100, 82, 97, 97, 95 94.0 ± 6.9

0.200 5 95, 100, 105, 96, 101 98.9 ± 4.0

10.0 5 81, 92, 95, 93, 97 91.6 ± 6.4

Meal Dicamba 0.020 5 102, 101, 98, 111, 108 104 ± 5.3

0.200 5 97, 99, 96, 100, 94 96.9 ± 2.4

5-OH 

Dicamba

0.020 5 72, 108, 92, 77, 92 88.1 ± 14

0.200 5 98, 94, 88, 99, 90 93.4 ± 4.9

DCGA 0.020 5 99, 108, 102, 103, 102 102 ± 3.3

0.200 5 88, 86, 85, 88, 85 86.0 ± 1.5

DCSA 0.020 5 101, 96, 100, 90, 98 96.5 ± 4.4

0.200 5 82, 84, 86, 91, 89 86.2 ± 3.8

Hulls Dicamba 0.020 5 97, 100, 106, 99, 99 100 ± 3.4

0.200 5 97, 101, 102, 100, 99 100 ± 2.1

5-OH 

Dicamba

0.020 5 87, 78, 106, 89, 97 91.2 ± 10

0.200 5 114, 107, 117, 99, 105 108 ± 7.4

DCGA 0.020 5 116, 117, 115, 121, 112 116 ± 3.4

0.200 5 89, 86, 86, 84, 82 85.2 ± 2.4

DCSA 0.020 5 109, 102, 94, 97, 96 99.5 ± 6.1

0.200 5 96, 102, 92, 100, 99 97.4 ± 3.9 

Alkali 

Refined Oil

Dicamba 0.020 5 99, 96, 97, 99, 98 97.6 ± 1.2

0.200 5 99, 100, 105, 99, 97 100 ± 2.8

5-OH 

Dicamba

0.020 5 95, 101, 79, 92, 88 90.8 ± 8.0

0.200 5 110, 103, 88, 110, 100 102 ± 9.0

DCGA 0.020 5 100, 102, 99, 103, 113 103 ± 5.7

0.200 5 97, 89, 92, 92, 91 91.8 ± 2.8

DCSA 0.020 5 102, 93, 90, 93, 100 95.2 ± 5.1

0.200 5 103, 106, 100, 104, 105 103 ± 2.1
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 11 of 15

TABLE C.1. Summary of Method and Concurrent Recoveries of Dicamba and its Metabolites from 

Cotton Matrices

Matrix Analyte Spike 

Level

(ppm)

Sample 

Size (n)

Recoveries

(%)1

Mean ± 

Std. Dev. 

(%)2

Concurrent Recoveries

Undelinted 

Cotton seed

Dicamba 0.02 3 78.1, 118, 105 100 ± 20

0.20 3 91.9, 103, 108 101 ± 8.3

5-OH 

Dicamba

0.02 2 85.5, 96.5 91.0

0.20 2 90.0, 89.5 89.8

DCGA 0.02 2 108, 119 113

0.20 2 109, 114 112

DCSA 0.02 2 84.9, 100 92.4

0.20 2 96.4, 98.7 97.6

RBD Oil Dicamba 0.02 2 115, 110 112

0.20 2 106, 105 105

5-OH 

Dicamba

0.02 2 119, 101 110

0.20 2 98.5, 108 103

DCGA 0.02 2 112, 106 109

0.20 2 97.0, 89.5 93.3

DCSA 0.02 2 108, 123 115

0.20 2 104, 101 103

Alkali 

Refined Oil

Dicamba 0.02 2 103, 109 106

0.20 2 101, 104 102

5-OH 

Dicamba

0.02 2 94.5, 75.5 85.0

0.20 2 92.0, 114 103

DCGA 0.02 2 120, 119 120

0.20 2 99.5, 99.0 99.3

DCSA 0.02 2 113, 97.5 105

0.20 2 109, 105 107

Hulls Dicamba 0.02 3 109, 120, 101 110 ± 9.3

0.20 3 79.0, 107, 103 96.4 ± 15

5-OH 

Dicamba

0.02 2 87.5, 99.5 93.5

0.20 2 84.5, 91.5 88.0

DCGA 0.02 2 112, 106 109

0.20 2 106, 104 105

DCSA 0.02 2 95.9, 96.4 96.1

0.20 2 98.1, 97.2 97.6

Meal Dicamba 0.02 2 98.8, 114 106

0.20 2 101, 103 102

5-OH 

Dicamba

0.02 2 100, 79.0 89.5

0.20 2 91.5, 92.5 92.0

DCGA 0.02 2 104, 104 104

0.20 2 111, 109 110

DCSA 0.02 2 79.8, 87.4 83.6

0.20 2 94.1, 105 99.8

1 The concurrent recoveries were corrected for apparent residues in the unfortified control samples.

2

 Standard deviation is not applicable for sample sizes n < 3 samples.
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728703 Page 12 of 15

3

 Recoveries for method validation undelinted cotton seed are also presented in the crop field trial DER (refer to 

48728703.DER1).

TABLE C.2. Summary of Storage Conditions.

Matrix Analyte Storage Temperature Actual Storage 

Duration1

Limit of Demonstrated Storage Stability2

Dicamba

Undelinted Cotton 

Seed

Dicamba Ambient at field sites;

-12 °C at processor;

-20 °C at analytical 

laboratory

152-196 days 

(5.0-6.4 months)

Residues of dicamba are stable during freezer 

storage for up to 277 days (9 months) in 

undelinted cotton seed. 

Hulls 33-40 days 

(1.1-1.3 months)

Storage stability data for the processed 

fractions was not provided. However, storage 

stability data is not required as the processed 

fractions were generally analyzed within 30 

days of processing.

Meal 26-27 days 

(0.9 months)

Alkali Refined Oil 24-25 days 

(0.8 months)

RBD Oil 19-20 days 

(0.6-0.7 months)

Dicamba Metabolites

Undelinted Cotton 

Seed

5-OH 

Dicamba, 

DCGA, 

DCSA

Ambient at field sites;

-12 °C at processor;

-20 °C at analytical 

laboratory

152-189 days

(5.0-6.2 months)

Residues of dicamba, DCGA, and DCSA are 

stable during freezer storage for up to 277 

days (9 months) in undelinted cotton seed. 

The stability of 5-OH dicamba was not 

determined concurrently because it was not 

found in undelinted cotton seed.

Hulls 33-34 days

(1.1 months)

Storage stability data for the processed 

fractions was not provided. However, storage 

stability data is not required as the processed 

fractions were generally analyzed within 30 

days of processing.

Meal 26-27 days

(0.9 months)

Alkali Refined Oil 24-25 days 

(0.8 months)

RBD Oil 19-20 days 

(0.6-0.7 months)

1

 Interval from harvest/processing to analysis; all samples were analyzed on the day of extraction. The samples were processed 

within 118-169 days of harvest.

2 Refer to the 860.1380 der for MRID 48728704. 
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

 DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

 Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

DP# 404821/MRID No. 48728703 Page 13 of 15

TABLE C.3. Residue Data for Dicamba and Metabolites from Cotton Processing Studies1

RAC Processed 

Commodity

Total 

Rate

lb ae/A

(kg ae/A)

TRT2 PHI

(days)

Residues (ppm)3 Processing Factor4,5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Fisk, Butler, MO; 2010 (MO1)

Cotton Undelinted Seed 2.0

(2.2)

2 79 <0.02 <0.02 <0.02 <0.02 <0.08 -- -- -- -- --

Hulls <0.02 <0.02 0.02 0.02 <0.08 NC5 NC >1.0x 1.0x 1.1x

Meal <0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC NC NC

Alkali Refined 

Oil

<0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC NC NC

RBD Oil <0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC NC NC

Cotton Undelinted Seed 2.0

(2.2)

4 7 0.70 <0.02 0.04 0.03 <0.78 -- -- -- -- --

Hulls 0.70 <0.02 0.05 0.03 <0.79 1.0x NC 1.3x 1.0x 1.0x

Meal 0.22 <0.02 <0.02 <0.02 <0.28 0.31x NC 0.50x <0.67x 0.35x

Alkali Refined 

Oil

<0.02 <0.02 <0.02 <0.02 <0.08 <0.03x NC <0.50x <0.67x 0.10x

RBD Oil <0.02 <0.02 <0.02 <0.02 <0.08 <0.03x NC <0.50x <0.67x 0.10x

Uvalde, Uvalde, TX; 2010 (TX4)

Cotton Undelinted Seed 2.0

(2.2)

2 71 <0.02 <0.02 <0.02 <0.02 <0.08 -- -- -- -- --

Hulls <0.02 <0.02 <0.02 0.02 <0.08 NC NC NC >1.0x 1.0x

Meal <0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC >1.0x 1.0x

Alkali Refined 

Oil

<0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC NC NC

RBD Oil <0.02 <0.02 <0.02 <0.02 <0.08 NC NC NC NC NC

Cotton Undelinted Seed 2.0

(2.2)

4 6 0.60 <0.02 0.04 0.05 <0.69 -- -- -- -- --

Hulls 0.16 <0.02 0.08 0.06 <0.26 0.27x NC 2.0x 1.2x 0.37x

Meal <0.02 <0.02 <0.02 <0.02 <0.08 <0.03x NC <0.50x <0.40x 0.12x

Alkali Refined 

Oil

<0.02 <0.02 <0.02 <0.02 <0.08 <0.03x NC <0.50x <0.40x 0.12x

RBD Oil <0.02 <0.02 <0.02 <0.02 <0.08 <0.03x NC <0.50x <0.40x 0.12x
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

 DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

 Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

DP# 404821/MRID No. 48728703 Page 14 of 15

TABLE C.3. Residue Data for Dicamba and Metabolites from Cotton Processing Studies1

RAC Processed 

Commodity

Total 

Rate

lb ae/A

(kg ae/A)

TRT2 PHI

(days)

Residues (ppm)3 Processing Factor4,5

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Dicamba 5-OH 

Dicamba

DCGA DCSA Combined 

Residues

Average

Cotton Undelinted Seed 2.0

(2.2)

2 71-79 -- -- -- -- --

Hulls NC NC 1.0x 1.0x 1.0x

Meal NC NC NC 1.0x 1.0x

Alkali Refined 

Oil

NC NC NC NC NC

RBD Oil NC NC NC NC NC

Cotton Undelinted Seed 2.0

(2.2)

4 6-7 -- -- -- -- --

Hulls 0.63x NC 1.6x 1.1x 0.69x

Meal 0.17x NC 0.50x 0.53x 0.23x

Alkali Refined 

Oil

0.03x NC 0.50x 0.53x 0.11x

RBD Oil 0.03x NC 0.50x 0.53x 0.11x

Cotton Undelinted Seed 2.0

(2.2)

2-4 6-79 -- -- -- -- --

Hulls 0.63x NC 1.4x 1.1x 0.86x

Meal 0.17x NC 0.50x 0.69x 0.49x

Alkali Refined 

Oil 0.03x

NC

0.50x 0.53x 0.11x

RBD Oil 0.03x NC 0.50x 0.53x 0.11x

1 Each trial site was planted with Event MON 88701 cotton that is tolerant to dicamba herbicide and glufosinate-ammonium herbicide.

2 TRT 2: Applications made at preemergence, the 6-leaf stage, and at the first white flower + 15 days stage; EP: Clarity. TRT 4: applications made at the 6-leaf stage, the 

first white flower + 15-days stage, the first open boll stage, and at 7 days prior to harvest; EP: Clarity. 

3 The LOQs were 0.02 ppm per analyte per matrix. Residues for individual analytes are presented per se and reflect the raw data. Combined residues were calculated by 

the study reviewer and are expressed in terms of parent equivalents. Quantifiable residues of 5-OH dicamba, DCSA, and DCGA were converted to parent equivalents by 

the study reviewer using molecular weight conversion factors of 0.933, 1.068, and 0.991, respectively. When calculating combined residues, the LOQ was used for values 

reported as ND or between the LOD and LOQ.

4

 Processing Factor = [Measured residue for analyte in the processed fraction] / [Measured residue for analyte in the RAC]. 

5 NC = Not calculated; residues were below the LOQ in the RAC and processed fraction.
 Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.4.5/OPPTS 860.1520/OECD IIA 6.5.4 and IIIA 8.5

Processed Food and Feed – Dicamba-Tolerant Cotton (Event MON 88701)

DP# 404821/MRID No. 48728703 Page 15 of 15

D. CONCLUSION

The submitted cotton processing study is acceptable. Following three or four applications of the 

4 lb ae/gal SC formulation at a total rate of 2 lb ae/A, using PHIs of 71-79 days and 6-7 days, 

respectively, the combined residues of dicamba, 5-OH dicamba, DCGA, and DCSA (in parent 

equivalents) were below the LOQ (<0.08)-<0.78 ppm in/on undelinted cotton seed (RAC), 

<0.081-<0.79 ppm in hulls, below the LOQ (<0.08)-<0.28 ppm in meal, and below the LOQ 

(<0.08 ppm) in alkali refined oil and RBD oil. The processing data indicate that the combined 

residues do not concentrate in hulls, meal, alkali refined oil, or RBD oil (average processing 

factors of 0.86x, 0.49, 0.11x, and 0.11x, respectively). The observed concentration factors were 

less than the theoretical concentration factors.

Samples were analyzed using acceptable methods, and the study is supported by adequate 

storage stability data.

E. REFERENCES

None.

F. DOCUMENT TRACKING

Petition Number(s): 2F8067

DP Barcode(s): 408384

PC Code: 029801, 029802, 029806, 128931, 128944, & 129043

Template Version June 2005
Dicamba/MON 11900/PC Code 12893 1/Monsanto Company 

DACO 7.3/0PPTS 860.1 380/0ECD llA 6. 1.1 and lllA 8.1.1 

Storage Stability - Dicamba-Toleranl Canon (Event MO 8870 I) 

Primary Evaluator 

Versar. [nc. - ,., Approved by ( _./~ ---f-c-,i. ~ 

A:~,.__._;._ __/ 

Peter Savoia, Chemist, OCSPP-HED-RAB V/Vll 

Date: 11115/2012 

Date: 04/22/2013 

Note: This Data Evaluation Record (DER) was originally prepared under contract by Versar, Inc. (6850 Versar 

Center, Springfield. VA 22151; submitted 11 /1 5/1 2). The DER has been reviewed by HED and revised to reflect 

current Office of Pesticide Programs (OPP) policies. 

STUDY REPORT: 

48728704. Maher. D.; Foster, J. (201 2) Determination of the Stability of Dicamba Residues in 

Dicamba-Tolerant Cotton under Frozen Storage Conditions. Project Number: 

REG/I 0/504/0CR, MSL0023058. Unpublished study prepared by Monsanto Company. l 44p. 

EXECUTIVE SUMMARY: 

Monsanto has submitted the results of a storage stability study with fi eld-incurred residues of 

dicamba and its metabolites 3,6-dichlorosalicylic acid (DCSA) and 3,6-dichlorogentisic acid 

(DCGA) in/on dicamba-tolerant cotton identified as Event MON 88701 (formerly GH_S26695). 

Event MON 88701 cotton expresses a modified dicamba mono-oxygenase (OMO) gene deri ved 

from Stenotrophomonas maltophi/ia and the bialaphos resistance (BAR) gene isolated from 

Streptomyces hygroscopicus. The expression of OMO confers dicamba tolerance and the 

expression of BAR confers glufosinate tolerance to Event MON 88701 cotton. Samples of 

undelinted cotton seeds were obtained from a crop field trial conducted by Monsanto (MRID 

48728703). Samples were collected 6 days following the last of four post-emergence broadcast 

applications of a 4 lb ae/gal water soluble concentrate (SL) formulation of dicamba 

diglycolan1ine salt (Clarity Herbicide; MON 54140) at 0.5 lb ae/ A (0.56 kg ae/ha), for a total 

application rate of2.0 lb ae/A (2.2 kg ae/ha). The applications were made at the 6-leaf stage. 

first white flower + 15 days stage, first open boll stage and 7-days preharvest. Samples were 

placed in frozen storage (:5-1 0 °C) from the time of initial sampling/milling until analysis at - 0, 

1, 2, 4, 6 and 9 months from the initiation of the storage stability study. 

Undelinted cotton seed samples were analyzed for residues of dicamba. DCSA and DCGA using 

liquid chromatography with tandem mass spectrometry detection (LC/MS/MS), Monsanto 

method AG-ME-1381. The validated limit of quantitation (LOQ; determined as the lowest level 

of method validation, LLMV) was 0.02 ppm for dicamba. DCSA and DCGA. The method was 

acceptable for data collection based on adequate method validation and concurrent recovery data. 

The results of the study indicate that field-incurred residues of dicamba and metabolites DCSA 

and DCGA are relatively stable in/on samples of undelinted cotton seed stored frozen at :5-10 °C 

for up to 9 months. Corrected mean recoveries at 9 months (calculated as percentage of the 0-

month results) were 76%, 117% and 95%, respectively. for dicamba. DCGA and DCSA. 

0408384/MRlD No. 48728704 Page I of9 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 2 of 9

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, the storage stability data are classified as 

scientifically acceptable. The acceptability of this study for regulatory purposes is addressed in 

the forthcoming U.S. EPA Residue Chemistry Summary Document, D408384.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and No Data 

Confidentiality statements were provided. No deviations from regulatory requirements were 

reported which would have an impact on the validity of the study. 

A. BACKGROUND INFORMATION

Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a selective benzoic acid herbicide registered 

for the control of weeds prior to their emergence. The Dicamba Reregistration Eligibility 

Decision (RED) was issued December 2005. The chemical structure and nomenclature of 

dicamba and its metabolites DSCA and DCGA are presented in Table A.1. The physicochemical 

properties of the technical grade of dicamba acid are presented in Table A.2. 

TABLE A.1. Test Compound Nomenclature.

Compound

Common name Dicamba

Company experimental name MON 11900

IUPAC name 3,6-dichloro-o-anisic acid or 3,6-dichloro-2-methoxybenzoic acid

CAS name 3,6-dichloro-2-methoxybenzoic acid 

CAS registry number 1918-00-9 (dicamba acid), 104040-79-1 (diglycolamine salt), or 53404-28-7 

(monoethanolamine salt)

End-use product Clarity® Herbicide: SL formulation containing 4 lb ae/gal

Compound

Common name DCSA

Company experimental name 3,6-dichlorosalicylic acid; MON 52708

IUPAC/CAS name 3,6-dichloro-2-hydroxybenzoic acid

CAS registry number 3401-80-7
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 3 of 9

TABLE A.1. Test Compound Nomenclature.

Compound

Common name DCGA

Company experimental name 3,6-dichlorogentisic acid (DCGA); MON 52724

IUPAC/CAS name 2,5-dichloro-3,6-dihydroxybenzoic acid

CAS registry number 18688-01-2

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Dicamba.

Parameter Value Reference

Melting point 114-116 C (PAI)

90-100 C (87% TGAI)

Residue Chemistry Chapter of the 

Dicamba RED, DP# 317699, 12/20/05, 

C. Olinger pH 2.5-3.0 (87% TGAI)

Density 1.57 g/mL at 25 C (87% TGAI)

Water solubility 0.5 g/100 mL at 25 C (PAI)

Solvent solubility g/100 mL at 25 C (PAI)

dioxane 118.0

ethanol 92.2

isopropyl alcohol 76.0

methylene chloride 26.0

acetone 17.0

toluene 13.0

xylene 7.8

heavy aromatic naphthalene 5.2

Vapor pressure 3.4 x 10-5 mm Hg at 25 C (PAI)

Dissociation constant, pKa 1.97 (PAI)

Octanol/water partition coefficient, Log(KOW) 0.1 (PAI)

UV/visible absorption spectrum neutral: 511 (275 nm)

acidic (pH 0-1): 1053 (281 nm)

basic (pH 13-14): 469 (274 nm)

B. EXPERIMENTAL DESIGN

B.1. Sample Handling and Preparation

The storage stability study was conducted by Monsanto Company at its Environmental Sciences 

Technology Center in St. Louis, Missouri. 

Undelinted cotton seed samples were obtained from a crop field trial study conducted by 

Monsanto (MRID 48728703) using dicamba-tolerant cotton identified as Event MON 88701 

(formerly GH_S26695). Event MON 88701 cotton expresses a modified dicamba monooxygenase (DMO) gene derived from Stenotrophomonas maltophilia and the bialaphos 

resistance (BAR) gene isolated from Streptomyces hygroscopicus. The expression of DMO 

confers dicamba tolerance and the expression of BAR confers glufosinate tolerance to Event 

MON 88701 cotton. 
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 4 of 9

In one trial conducted in Hockley, TX (Site TX2), samples of undelinted cotton seeds were 

collected from treatment plot 4 (TRT 4) following the last of four post-emergence broadcast 

applications of a 4 lb ae/gal SL formulation of dicamba diglycolamine salt (Clarity Herbicide; 

MON 54140) at 0.5 lb ae/A (0.56 kg ae/ha), for a total application rate of 2.0 lb ae/A (2.2 kg 

ae/ha). The applications were made at the 6-leaf stage, first white flower +15 days stage, first 

open boll stage and 7-days preharvest using a backpack sprayer in spray volumes of ~20 gal/A

(187 L/ha). A non-ionic surfactant (NIS) and ammonium sulfate (AMS) were added to the spray 

mixture. 

Single composite cotton seed samples (~1 kg) were collected from the control and treated plot 6

days after the last application and ginned at the field site one day after harvest. Samples were

stored at ambient temperature until ginning. The undelinted cotton seed samples were placed in 

frozen storage at the field trial site within 1 hour of sampling and shipped via ACDS freezer 

truck to Monsanto the next day (2 days after harvest). The samples were placed in frozen storage 

at Monsanto (-10 °C) and were removed from frozen storage and analyzed at intervals of ~0, 1, 

2, 4, 6 and 9 months from the initiation of the storage stability study, which occurred 121 days 

after harvest. Actual storage durations were 0, 31, 60, 125, 194, and 277 days. The undelinted 

cotton seed subsample used for the storage stability study was prepared at Monsanto two days 

before the Day 0 analysis (119 days after harvest) using a cryomill, which pulverizes samples 

into a fine powder at cryogenic temperatures. Concurrent recovery samples were fortified at 

each interval at 0.04, 0.3 and 2.0 ppm, using a mixed standard containing dicamba and DCSA 

and a separate solution containing only DCGA. 

A subsample of the treated undelinted cotton seed sample was originally milled 20 days after 

harvest and analyzed 38 days after harvest, as part of the crop field trial study (see above). Due 

to an inadequate amount of milled material, new subsamples were milled 119 days after harvest 

for use in the storage stability study. Three replicates of the original milled subsample were reanalyzed shortly after the initiation of the storage stability study to assess stability of residues 

during this period. The results of the original and repeat analyses were similar. The Study 

Author attributed differences between residues in the original analysis for the crop field trial 

study and the Day 0 analysis for the storage stability study to variability between subsamples.

B.2. Analytical Methodology

Samples were analyzed for residues of dicamba and the metabolites DCGA and DCSA using a 

LC/MS/MS method from Monsanto: Analytical Method AG-ME-1381-01. For a complete 

description of the LC/MS/MS method, refer to the 860.1340 DER for MRID 48728702. 

Briefly, samples were extracted with acetonitrile:water (40:60, v:v). An aliquot of the extract 

was hydrolyzed in 1 N HCl at 95 °C in an oven. The hydrolysate was partitioned with ethyl 

acetate:isooctane (20:80, v:v). Water was added to the organic phase and the sample was 

concentrated by evaporation until only the aqueous solution remained. The samples were 

acidified and analyzed using LC/MS/MS.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 5 of 9

The LOQ (determined as the LLMV) was 0.02 ppm for dicamba, DCSA and DCGA in 

undelinted cotton seed. We note that the petitioner also presented calculated values statistically 

determined for the LOD and LOQ based on recoveries obtained at the 0.020 ppm fortification 

level from the method validation study. The LODs were 0.0089, 0.0035 and 0.0041 ppm for 

dicamba, DCSA and DCGA, respectively. The LOQs were 0.0266, 0.0105 and 0.0121 ppm for 

dicamba, DCSA and DCGA, respectively.

The analytical method was validated prior to the storage stability study and in conjunction with 

analysis of frozen storage stability samples.

C. RESULTS AND DISCUSSION

Concurrent recovery data are presented in Table C.1. The method validation data are presented 

in the DER for MRID 48728703. The data indicate that the LC/MS/MS was adequate for 

determination of residues of dicamba, DCSA and DCGA in undelinted cotton seed. Concurrent 

recoveries were within the acceptable range of 70-120% for all analytes in samples fortified at 

0.04, 0.30, and 2.0 ppm each. Apparent residues in control samples were less than the method 

LOQ (<0.02 ppm), and adequate example chromatograms were provided. Concurrent recoveries 

were corrected for residues found in the control samples. 

The results of the storage stability study are presented in Table C.2. The study results indicate 

that residues of dicamba, DCSA and DCGA are stable in undelinted cotton seed stored frozen (≤-

10 °C) for up to 9 months. Corrected mean recoveries were 76%, 117% and 95%, respectively, 

for dicamba, DCGA and DCSA in/on undelinted cotton seed at 9 months (calculated as 

percentage of the 0-month results). 

A graph depicting the storage stability of field-incurred residues of dicamba and its metabolites 

DCSA and DCGA in/on undelinted cotton seed is presented in Figure C.1.
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 6 of 9

TABLE C.1 Summary of Concurrent Recoveries of Dicamba and its Metabolites from Undelinted Cotton 

Seed.

Matrix Analyte Storage 

Interval 

(Months)

Fortification 

Level

(ppm)

Sample size (n) Recoveries1

(%)

Mean ± Std 

Dev.2

(%) 

Undelinted 

cotton seed

Dicamba 0 0.04 1 79.8

0.30 1 98.0 92.9 ± 11.5

2.00 1 101

1 0.04 1 90.3

0.30 1 96.3 97.0 ± 7.39

2.00 1 105

2 0.04 1 97.3

0.30 1 96.0 97.6 ± 1.77

2.00 1 99.5

4 0.04 1 107

0.30 1 111 111 ± 4.00

2.00 1 115

6 0.04 1 117

0.30 1 80.2 91.1 ± 22.3

2.00 1 76.7

9 0.04 1 112

0.30 1 105 105 ± 6.26

2.00 1 99.5

DCGA 0 0.04 1 103

0.30 1 107 105 ± 2.08

2.00 1 104

1 0.04 1 83.5

0.30 1 84.4 84.7 ± 1.43

2.00 1 86.3

2 0.04 1 96.7

0.30 1 101 100 ± 3.22

2.00 1 103

4 0.04 1 104

0.30 1 99.0 103 ± 3.21

2.00 1 105

6 0.04 1 94.0

0.30 1 95.3 93.4 ± 2.32

2.00 1 90.8

9 0.04 1 95.0

0.30 1 114 105 ± 9.54

2.00 1 106

DCSA 0 0.04 1 99.9

0.30 1 115 112 ± 11.3

2.00 1 122

1 0.04 1 115

0.30 1 108 105 ± 12.3

2.00 1 91.0

2 0.04 1 99.4

0.30 1 92.2 94.5 ± 4.25

2.00 1 91.9

4 0.04 1 98.7

0.30 1 98.5 95.0 ± 6.29

2.00 1 87.7

6 0.04 1 79.0

0.30 1 70.6 76.0 ± 4.71

2.00 1 78.5
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 7 of 9

TABLE C.1 Summary of Concurrent Recoveries of Dicamba and its Metabolites from Undelinted Cotton 

Seed.

Matrix Analyte Storage 

Interval 

(Months)

Fortification 

Level

(ppm)

Sample size (n) Recoveries1

(%)

Mean ± Std 

Dev.2

(%) 

9 0.04 1 98.5

0.30 1 94.2 97.7 ± 3.01

2.00 1 100

1 Recovery values were corrected for background levels in controls. 

2 Standard deviations were determined by the study reviewer.

TABLE C.2 Stability of Field-Incurred Residues of Dicamba, DCGA and DCSA in Dicamba-Resistant 

Undelinted Cotton Seed Following Storage at -10°C

Commodity Analyte Spike 

Level

(ppm)

Storage 

interval

(months)

Recovered 

Residues

(ppm)

Mean 

Recovered 

Residues 

(ppm)

Mean 

Recovery1

(%)

Corrected 

Recovered 

Residues2

(ppm)

Corrected

Mean 

Recovery3

(%)

Undelinted

cotton seed

Dicamba Incurred4

0

1.01, 0.91, 

0.78, 0.83, 

0.78, 0.82

0.85 100 0.91 --

1

0.82, 0.76, 

0.79, 0.75 0.78 92 0.80 88

2

0.70, 0.89, 

0.90, 0.88 0.84 99 0.86 94

4

0.94, 0.82, 

0.88, 1.00 0.91 107 0.82 90

6

0.54, 0.62, 

0.70, 0.72, 

0.64, 0.72

0.66 78 0.72 79

9

0.72, 0.70, 

0.80, 0.75, 

0.72, 0.71

0.73 86 0.70 76

DCGA Incurred4

0

0.13, 0.12, 

0.12, 0.13, 

0.11, 0.12

0.12 100 0.11 --

1

0.14, 0.14, 

0.16, 0.15 0.14 117 0.17 145

2

0.12, 0.13, 

0.13, 0.14 0.13 108 0.13 114

4

0.14, 0.13, 

0.12, 0.12 0.13 108 0.13 110

6

0.13, 0.14, 

0.15, 0.13, 

0.12, 0.14

0.13 108 0.14 122

9

0.14, 0.13, 

0.14, 0.15, 

0.14, 0.13

0.14 117 0.13 117

DCSA Incurred4

0

0.24, 0.24, 

0.24, 0.22, 

0.24, 0.23

0.23 100 0.21 --

1

0.22, 0.21, 

0.23, 0.24 0.22 96 0.21 102

2

0.20, 0.24, 

0.22, 0.25 0.23 100 0.24 119
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 8 of 9

TABLE C.2 Stability of Field-Incurred Residues of Dicamba, DCGA and DCSA in Dicamba-Resistant 

Undelinted Cotton Seed Following Storage at -10°C

Commodity Analyte Spike 

Level

(ppm)

Storage 

interval

(months)

Recovered 

Residues

(ppm)

Mean 

Recovered 

Residues 

(ppm)

Mean 

Recovery1

(%)

Corrected 

Recovered 

Residues2

(ppm)

Corrected

Mean 

Recovery3

(%)

4

0.21, 0.20, 

0.19, 0.21 0.20 87 0.21 103

6

0.12, 0.18, 

0.18, 0.17, 

0.18, 0.18

0.17 74 0.22 109

9

0.20, 0.17, 

0.18, 0.21, 

0.18, 0.18

0.19 83 0.19 95

1

 Recoveries for stored samples calculated by Versar reviewer as percentage of 0-month results. 

2

 Corrected by the study reviewer for mean concurrent recovery (Table C.1.)

3

 Calculated by the study reviewer as (ppm corrected recovered residues in sample ÷ ppm corrected recovered residues in 0-day 

sample).

4 

 Residues incurred following four applications of MON 54140, a SL formulation of dicamba diglycolamine salt containing 4 lb 

ae/gal (480 g/L), to cotton at application rates of ~0.5 lb ae/A/application (0.56 kg ae/ha).

Figure C.1 Graph of Dicamba Storage Stability in Undelinted Cotton Seed
Dicamba/MON 11900/PC Code 128931/Monsanto Company

DACO 7.3/OPPTS 860.1380/OECD IIA 6.1.1 and IIIA 8.1.1

Storage Stability – Dicamba-Tolerant Cotton (Event MON 88701)

D408384/MRID No. 48728704 Page 9 of 9

D. CONCLUSION

The storage stability data are adequate and demonstrate the stability of field-incurred residues of 

dicamba and metabolites DCSA and DCGA in/on samples of undelinted cotton seed stored 

frozen for up to 9 months at ≤-10 °C. An acceptable method was used for quantitation of 

residues.

E. REFERENCES

Residue Chemistry Chapter of the Dicamba RED, DP# 317699, 12/20/05, C. Olinger

F. DOCUMENT TRACKING

Petition Number(s): 2F8067

DP Barcode(s): 408384

PC Code: 029801, 029802, 029806, 128931, 128944, & 129043