			

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

January 31, 2006

	

MEMORANDUM

SUBJECT:	Residue Chemistry Chapter for the Monosodium and Disodium Salts
of Methanearsonic Acid Reregistration Eligibility Decision (RED)

DP Barcode:  D309106

		PC Code(s):   013802 and 013803

		Chemical Class: Organo Arsenical

FROM:	P. Yvonne Barnes, Chemist

		Reregistration Branch II

		Health Effects Division (7509C)

		

		and

		Sherrie L. Kinard, Chemist

		Reregistration Branch II

		Health Effects Division (7509C)

			

THROUGH:	Alan Nielsen, Branch Senior Scientist

		Reregistration Branch II

		Health Effects Division (7509C)

		

		

TO:		Diana Locke, Ph.D.

		Reregistration Branch II

		Health Effects Division (7509C)

  SEQ CHAPTER \h \r 1 The summary analytical chemistry and residue data
document was originally prepared under contract by Dynamac Corporation,
The Dynamac Building 2275 Research Boulevard Rockville, MD 20850-3268.

METHANEARSONIC ACID (MAA) AND SALTS

REREGISTRATION ELIGIBILITY DECISION

RESIDUE CHEMISTRY CONSIDERATIONS

Case number 2395 for PC Codes 013802 and 013803

	

  SEQ CHAPTER \h \r 1 TABLE OF CONTENTS	page

 TOC \f 

INTRODUCTION	3

REGULATORY BACKGROUND	3

SUMMARY OF SCIENCE FINDINGS	5

GLN 860.1200:  Directions for Use	5

GLN 860.1300:  Nature of the Residue - Plants	13

GLN 860.1300:  Nature of the Residue - Animals	14

GLN 860.1340:  Residue Analytical Methods	15

GLN 860.1360:  Multiresidue Methods	16

GLN 860.1380:  Storage Stability Data	16

GLN 860.1500:  Crop Field Trials	16

GLN 860.1520:  Processed Food/Feed	18

GLN 860.1480:  Meat, Milk, Poultry, Eggs	18

GLN 860.1400:  Water, Fish, and Irrigated Crops	19

GLN 860.1460:  Food Handling	19

GLN 860.1850 and 860.1900:  Confined/Field Accumulation in Rotational
Crops	19

TOLERANCE REASSESSMENT SUMMARY	21

Tolerances Listed Under 40 CFR §180.289(a)	21

Tolerances to be Proposed Under 40 CFR §180.289(a)	22

CODEX HARMONIZATION	23

DIETARY EXPOSURE ASSESSMENT	23

AGENCY MEMORANDA RELEVANT TO REREGISTRATION	23

MASTER RECORD IDENTIFICATION NUMBERS	29

 

				

METHANEARSONIC ACID (MAA) AND SALTS

REREGISTRATION ELIGIBILITY DECISION

RESIDUE CHEMISTRY CONSIDERATIONS

Case number 2395 for PC Codes 013802 and 013803 

INTRODUCTION

Methanearsonic acid and its salts are selective post-emergence organic
arsenical herbicides registered for use on citrus, cotton, non-bearing
fruit and nut trees (including almond, apple, cherry, grapefruit, lemon,
lime, orange, peach, pear, pecan, plum/prune, tangerine, walnut), and
non-crop areas (including lawns and ornamental turf).  The
methanearsonic acid and its salts comprise Case Number 2395 and the PC
codes listed below.

List of Methanearsonic Acid and Salts with Corresponding PC Codes.

PC Code	Chemical Name	Status

013802	MAA, disodium salt (DSMA)	Currently being supported for
reregistration and has active products with food/feed uses.

013803	MAA, monosodium salt (MSMA)	Currently being supported for
reregistration and has active products with food/feed uses.

013804	MAA, octylammonium salt	Not being supported and there are no
active products.

013805	MAA, dodecylammonium salt	Not being supported and there are no
active products.

013806	MAA, calcium salt	No registered food/feed uses.



Disodium methanearsonic acid (DSMA, PC Code 013802) and monosodium
methanearsonic acid (MSMA, PC Code 013803) have active registered
products with food/feed uses.  The MAA Research Task Force supports the
reregistration of DSMA and MSMA, which consists of the following
conglomerate APC Holding Company, Luxembourg-Pamol, Inc., and
KMG-Bernuth, Inc.  The MAA Research Task Force proposes that the
registered DSMA and MSMA products marketed manufacturing-use and end-use
products under various trade names will become consistent with the
Master Labels issued by the Task Force.  

REGULATORY BACKGROUND

MAA and its salts are List B reregistration pesticides.  The
Methanearsonic Acid and Salts Phase 4 Reviews issued for DSMA and MSMA
on 03/26/1991 (C. Olinger).  Data-Call-In (DCI) Notices issued for DSMA
and MSMA on 06/14/1991, 03/03/1995, and 10/13/1995 requiring the
registrants to submit several residue chemistry studies in order to
fulfill reregistration requirements.  Members of the MAA Task Force have
submitted several of the studies requested in the DCIs, and these
studies have undergone Phase 5 Review.  The data requirements for a few
studies remain unfulfilled.  The information contained in this document
summarizes the Residue Chemistry Assessments with respect to the
reregistration of DSMA and MSMA.

Tolerances have been established [40 CFR §180.289(a)] for residues of
the herbicide methanearsonic acid, calculated as arsenic trioxide
(As2O3, also know as arsine), resulting from application of the disodium
and monosodium salts of methanearsonic acid in/on citrus fruit (0.35
ppm), cottonseed (0.7 ppm), and cottonseed hulls (0.9 ppm).

Cacodylic acid (Case Number 2080; PC Codes 012501 and 012502) is a
metabolite of MSMA, and is found in cotton and citrus raw agricultural
commodities (RACs) treated with MSMA. 

Tolerances have been established [40 CFR §180.311] for residues of the
defoliant cacodylic acid (dimethylarsinic acid), expressed as As2O3,
in/on cottonseed (2.8 ppm), kidney and liver of cattle (1.4 ppm), and in
meat, fat and meat by-products (except kidney and liver) of cattle (0.7
ppm).  According to 40 CFR §180.3(d)(4), where a tolerance is
established for more than one pesticide containing arsenic found in/on a
RAC, the total amount of such pesticide shall not exceed the highest
established tolerance, calculated as As2O3.  Figure 1 depicts the
chemical structures of MSMA, DSMA, and cacodylic acid.

Figure 1.  Chemical Structures of MSMA, DSMA, and Cacodylic Acid.

MSMA

(Monosodium salt of MAA)	

DSMA

(Disodium salt of MAA)	

Cacodylic acid



Published methods for the enforcement of tolerances for residues of
methanearsonic acid and cacodylic acid are found in the Pesticide
Analytical Manual (PAM) Vol. II.  These methods involve the conversion
of methanearsonic acid, cacodylic acid, as well as other arsenicals to
arsine and detection of arsine colorimetrically.  The methods have a
sensitivity of 0.05 ppm for MAA and 0.01 ppm for cacodylic acid. 
Although these subject methods are adequate to determine total residues
of arsenic (not speciation analysis) in/on raw agricultural commodities
from all potential sources of arsenic exposure including background
levels of arsenic, it is not adequate to perform speciation analyses for
residues of MAA or cacodylic acid in/on raw agricultural commodities.

SUMMARY OF SCIENCE FINDINGS

GLN 860.1200:  Directions for Use:  METHANEARSONIC ACID (MAA) AND SALT
MSMA

**Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:  METHANEARSONIC ACID (MAA) AND SALT
MSMA [continued]

**Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:  METHANEARSONIC ACID (MAA) AND SALT
MSMA [continued]

 **Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:   METHANEARSONIC ACID (MAA) AND SALT
DSMA

**Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:   METHANEARSONIC ACID (MAA) AND SALT
DSMA  [continued]

**Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:   METHANEARSONIC ACID (MAA) AND SALT
DSMA [continued]

**Master Label support by the MAA Task Force

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:   Cacodylic Acid

**Master Label support by the Luxembourg-Pamol, Incorporated

	MAATF/051209-323 dated December 09, 2005

GLN 860.1200:  Directions for Use:   Cacodylic Acid [continued]

**Master Label support by the Luxembourg-Pamol, Incorporated

	MAATF/051209-323 dated December 09, 2005

Citrus fruits and cotton are the only registered food/feed uses of DSMA
and MSMA.  DSMA and MSMA are also registered for uses on non-bearing
nuts and fruits with a restriction limiting application to crops that
will not bear nuts or fruit within one year of application; hence, the
non-bearing nut and fruit uses are consider non-food uses.

A comprehensive summary of the uses of DSMA and MSMA on citrus fruits
and cotton, based on the product labels registered to the members of the
MAA Task Force, is presented under guideline 860.1200 Directions for
Use.  These Master Labels include the use patterns, type and timing of
application, application limitations, maximum application rate, maximum
applications per-crop, and pre-grazing interval. For generating this
Residue Chemistry Chapter, the Agency examined the registered food/feed
use patterns and re-evaluated the available residue chemistry database.
Table B presents a tabular summary of the residue chemistry assessments
for reregistration of DSMA and MSMA.  

GLN 860.1300:  Nature of the Residue - Plants

The qualitative nature of the residue in plants is adequately
understood.  Acceptable metabolism studies on citrus and cotton have
been submitted by the MAA Task Force and reviewed by the Agency.  The
citrus and cotton studies were conducted using MSMA labeled with 14C in
the methyl group as the test substance.  The Agency previously specified
that translation of MSMA metabolism studies to DSMA is acceptable,
according to a Phase 4 response (03/26/1991 memo of C. Olinger).  The
results of these reviewed studies were presented on 12/19/1994 to the
HED Metabolism Committee (C. Swartz memo of 01/25/1995).  Based on the
metabolism studies conducted by the registrants for MSMA, as well as
metabolism data for MSMA and DSMA from published sources, the Committee
concluded that the residues of concern (i.e., that which is of
toxicological concern and requires regulation) associated with the use
of MSMA and DSMA are MSMA per se and cacodylic acid expressed as As2O3. 
This decision was predicated on the low rate or lack of demethylation,
and the inability to distinguish between background arsenic and arsenic
resulting from pesticide use.  The salient features of the conducted
plant metabolism studies are summarized below.

Citrus:  Lemon trees were treated three times with [14C] MSMA at 1x the
maximum label rate.  The three applications were made 104, 59, and 28
days PHI.  Lemon peel contained 0.44 ppm of radioactivity (53% of the
fruit TRR); lemon pulp contained 0.07 ppm of radioactivity (24% of the
TRR); and lemon juice contained 0.12 ppm (23% of the fruit TRR).  Lemon
matrices were subjected to solvent extraction.  Neither acid nor base
hydrolysis was required to release additional radioactive residues.  In
lemon peel, 94% of the radioactivity was identified, with 40.5% as MSMA
(including Unknown 1) and 54.2% as cacodylic acid.  In lemon pulp, 97%
of the radioactivity was identified, as (35.8% MSMA (including Unknown
1) and 61.2% as cacodylic acid.  In lemon juice, 92.1% of the
radioactivity was identified, 40.3% as MSMA (including Unknown 1) and
51.8% cacodylic acid.

Cotton:  Cotton plants that were in the mid-bloom stage were treated
with [14C] MSMA at 1.1x the maximum label rate. The treatments were made
with a 110 and 97 days PHI.  The total radioactive residue (TRR) in
treated mature cottonseed was 1.49 ppm.  Cottonseed was subjected to
solvent extraction, followed by acid and base hydrolysis.  Metabolites
were characterized and/or identified using HPLC, TLC, and GC/MS. 
Approximately 67% of the cottonseed TRR was identified as MSMA and
cacodylic acid.  Bound residues constituted 9% of the cottonseed TRR,
and the remaining radioactivity was either unidentified or was not
recovered through the extraction and hydrolysis procedures.

GLN 860.1300:  Nature of the Residue - Animals

The qualitative nature of the residue in animals is adequately
understood based on acceptable ruminant and poultry metabolism studies. 
The HED Metabolism Committee (C. Swartz memo of 01/25/1995) concluded
that there is no reasonable expectation of detectable MSMA residues of
concern in meat, milk, poultry, and eggs as a result of registered uses;
that is, residues in meat, milk, poultry, and eggs can be classified
under Category 3 of CFR §180.6(a).  Tolerances and feeding studies are
not required at this time.  A brief summary of the reviewed animal
metabolism studies is presented below.

Ruminants:  Two lactating goats were orally dosed with [14C] MSMA once
daily for seven days at a dietary level of 42 ppm (Ç40x the maximum
theoretical dietary exposure of Ç1.0 ppm burden to beef cattle).  It is
noted that various combinations of cottonseed, cotton hulls, and wet or
dried citrus pulp can be used as a cattle diet with dietary exposure
ranging from Ç0.6 ppm to 1.2 ppm.  In goat tissues, the TRR levels were
highest in kidney (0.292 ppm and 0.335 ppm) and liver (0.215 ppm and
0.249 ppm), and lowest in fat (0.012 ppm) and muscle (0.085 ppm to 0.106
ppm).  In milk, TRR levels ranged from 0.015 ppm to 0.038 ppm, with
radioactive residues reaching a plateau at days 3 or 5.  Goat tissue and
milk samples were subjected to solvent extraction; non-extractable
residues of certain tissue samples were subjected to acid, base, and
enzyme hydrolysis.  Residue components were characterized and/or
identified using TLC and HPLC.  MAA was identified in day-5 milk at 34%
TRR and in leg muscle at 3% TRR.  Cacodylic acid was the principal
residue component identified in liver at 74% TRR, in kidney at 85% TRR,
in loin muscle at 31% TRR, in leg muscle at 81% TRR, and in day-5 milk
at 15% TRR.			

Poultry:  Ten laying hens were orally dosed with [14C] MSMA once daily
for seven days at a dietary level of 42 ppm.  This dosage represents
>265x the maximum theoretical dietary exposure of 0.157 ppm, based on a
diet consisting of 20% cottonseed meal with cottonseed tolerance-level
residues of 0.7 ppm.  Total radioactivity accumulated to 0.340 ppm in
egg yolk and 0.108 ppm in egg white, and did not plateau over the 7-day
dosing period.  TRR levels in other tissues were 0.023 ppm (fat), 0.083
ppm (thigh muscle), 0.119 ppm (breast muscle), 0.101 ppm (liver), and
0.158 ppm (kidney).  Poultry eggs and tissue samples were subjected to
solvent extraction; non-extractable residues of certain tissue samples
were subjected to acid, base, and enzyme hydrolysis.  Metabolites were
characterized and/or identified using TLC and HPLC.  The principal
residues identified were MAA and cacodylic acid.  MAA was identified in
breast muscle at 4% TRR, in skin/fat at 17% TRR, and in egg yolk at 21%
TRR.  Cacodylic acid was identified in liver at 68% TRR, in kidney at
82% TRR, in breast muscle at 85% TRR, in thigh muscle at 28% TRR, in
skin/fat at 11% TRR, in egg yolk at 14% TRR, and in egg white at 74%
TRR.

GLN 860.1340:  Residue Analytical Methods

Plant commodities:  For tolerance enforcement, the Pesticide Analytical
Manual (PAM), Vol. II, lists two colorimetric methods for separate
determination of residues of methanearsonic acid and cacodylic acid
(Pesticide Regulation Section 180.289 and 180.311, respectively).  The
methods involve the digestion of the crop with a mixture of nitric and
sulfuric acids, the reduction of residues to arsine, and a colorimetric
determinative step using silver diethyldithiocarbamate or ammonium
molybdate.  The methods have a sensitivity of 0.05 ppm for MAA and 0.01
ppm for cacodylic acid.  The Phase 4 Reviews for MAA and cacodylic acid
requested that the registrant submit new enforcement methods for
determination of residues of concern in/on plant commodities.

For data collection, samples of citrus and cotton RACs that were
collected from the submitted field and processing studies were analyzed
for residues of MSMA and cacodylic acid using a gas chromatography
method with electron capture detection (GC/ECD).  Residues of DSMA are
converted to MSMA during the extraction process.  Briefly, residues are
extracted with water, and the extract is acidified.  Following washing
with hexane and diethyl ether, the extract is made alkaline with the
addition of sodium hydroxide and then concentrated.  The concentrated
extract is acidified and refluxed for 16-18 hours.  Following cleanup by
solid phase extraction, residues are derivatized with
methylthioglycolate and partitioned into hexane.  The hexane phase is
analyzed by GC/ECD for the derivatized residues of MSMA and cacodylic
acid.  Depending on the matrix, the reported LOQs of the analytical
method were 0.04-0.05 ppm.  The method was adequately validated by the
registrants.  Radiovalidation data have also been submitted and
reviewed; the data indicate that the GC/ECD can adequately and
separately quantitate residues of MSMA and cacodylic acid in/on aged
samples of lemons generated from a citrus metabolism study.

Since the enforcement methods listed in PAM Volume II are not specific
to arsenic residues resulting form the use of DSMA and MSMA, the Agency
recommends that this GC/ECD method be proposed as an enforcement method.
 The registrant is referred to OPPTS 860.1340 for specific requirements
concerning regulatory methods.  OPPTS 860.1340 requires that any
proposed enforcement method be subjected to an independent laboratory
validation (ILV) as per PR Notice 96-1.  If the Agency determines that
the registrant has submitted the results of a successful ILV trial by an
independent laboratory, then the method will be validated by Agency
chemists.

Animal commodities:  Analytical methods for eggs, milk, and animal
tissues are not required to support reregistration of DSMA and MSMA;
however, should the registrants submit cotton gin trash data or propose
in the future to additionally register feed crops which could
potentially increase the maximum theoretical dietary exposure of
residues of concern to animal commodities, then the Agency may require
an animal enforcement method.

It is noted that the MAA Task Force has submitted a GC/ECD method for
quantitation of MSMA and cacodylic acid residues in beef (fat, liver,
kidney and muscle) and milk.  In its review of the method, the Agency
then commented that the method may be acceptable for the reregistration
of cacodylic acid provided further method development are undertaken
prior to initiation of an ILV.

GLN 860.1360:  Multiresidue Methods

The reregistration requirements for multiresidue method testing
requirement for MSMA and cacodylic acid are waived.  Considering the
decision tree for PAM, Vol. I, Appendix II, Paragraph (d)(1) and
accompanying guidance found in the suggestions for producing quality
data, it is deemed unlikely that residues of MSMA and cacodylic acid
will be adequately recovered using any of the existing multiresidue
method protocols.  The Residue Chemistry Chapter for Cacodylic Acid
waived the multiresidue method testing requirement, and the HED’s
Chemistry Science Advisory Council, in a meeting conducted on
03/15/2000, concurred with this decision.  The 10/1999 PESTDATA database
(PAM, Vol. I, Appendix I) does not contain any information for MSMA or
cacodylic acid.	GLN 860.1380:  Storage Stability Data

Plant commodities:  No storage stability data are available to support
the storage conditions and intervals of samples collected from the
citrus and cottonseed processing studies which were stored frozen for
maximums of 15 and 9 months, respectively, after processing and prior to
residue analysis.  The registrants are required to submit data
investigating the frozen storage stability of residues of MSMA and
cacodylic acid in the processed fractions of citrus fruits (dried pulp,
oil, and juice) and cottonseed (meal, hulls, and refined oil) at the
maximum storage intervals.

Adequate storage stability data are available to support the storage
conditions and intervals of samples collected from field residue trials
and metabolism studies.  Residues of MSMA are stable under frozen
storage conditions in/on cottonseed for Ç20 months and in/on
grapefruit, lemons, and oranges for 15 months.  Storage stability data
from plant metabolism studies suggest that residues of cacodylic acid
are stable under frozen storage conditions for up to one year in/on
citrus fruit and cottonseed.

Animal commodities:  Storage stability data for animal commodities are
not part of the reregistration requirements because no tolerances exist
or are currently required for milk, eggs, and livestock tissues.

GLN 860.1500:  Crop Field Trials

The reregistration requirements for magnitude of the residue in/on
citrus fruit and cottonseed are fulfilled pending submission of
confirmatory data, label revisions, and tolerance reassessment.  Residue
data are required for cotton gin byproducts.

The MAA Task Force has submitted field residue data depicting the
magnitude of MSMA and cacodylic acid residues in/on citrus fruit and
cottonseed.  These data obtained using an analytical method (GC/ECD)
adequately validated for data collection.  Storage stability data
support the integrity of the residue data.  In general, the field
studies met the criteria for the required number of trials, and
conducted in locations representative of the major growing regions
specific to the crops tested.  The test systems utilized representative
product formulations, applied at maximum rates the registrants wish to
support, using application equipment in accordance with label
specifications.  A brief summary that lists the supporting residue data
for citrus fruit and cottonseed is presented below.

Citrus fruit:  In one study, 27 field trials were conducted to determine
the magnitude of MSMA and cacodylic acid residues in/on grapefruit,
lemons, limes, and oranges following side-by-side applications of
representative DSMA and MSMA formulations according to the use patterns
the registrants are supporting.  Mature fruits were collected at 0-day
PHI following the last of three applications of DSMA and MSMA
formulations at 4.9 lb a.i./A/application and 4.0 lb a.i./A/application,
respectively.  All treated citrus fruits each bore residues of MSMA
below the analytical method’s LOQ of 0.05 ppm; citrus fruit samples
from treated areas bore non-detectable (<0.05 ppm) residues of cacodylic
acid except for three samples.

												

The Agency is requiring confirmatory residue decline data to determine
whether residues of MSMA and cacodylic acid are taken up by plants at
longer PHIs.  A total of 9 residue decline trials on oranges (3 trials),
lemon (3 trials), and grapefruit (3 trials) should be conducted in major
citrus growing regions.  Representative DSMA and MSMA formulations
should be tested side-by-side in each trial site.					

The Agency also recommends label revisions to reflect the parameters of
use patterns for which adequate residue data are available.  No field
trial data are required to support the registered uses of MAA on
non-bearing citrus because product labels contain a restriction limiting
application to crops which will not bear fruit within one year (12
months) of application.

Cottonseed:  In one study, 23 field trials were conducted to determine
the magnitude of the residues of MSMA and cacodylic acid in/on delinted
cottonseed following applications of a representative MSMA formulation
according to two types of use patterns the registrants are supporting. 
The combined residues of MSMA and cacodylic acid in/on delinted
cottonseed harvested 71 days to 130 days were:  (i) <0.10 ppm to <0.29
ppm following two directed spray applications at 2 lb
a.i./A/application; and (ii) <0.10ppm to <0.20 ppm following a single
topical application at 1 lb a.i./A followed by a directed spray
application at 2 lb a.i./A. The RAC that was analyzed in the submitted
cotton field study was delinted cottonseed as opposed to undelinted
cottonseed as per Table 1 (OPPTS 860.1000); however, it is noted that
the field trials were initiated in the 1993 growing season which is
prior to the 1996 issuance of the revised Table 1.  The Agency is
requiring confirmatory field trial data on undelinted cottonseed. 
Residue data are also required for cotton gin byproducts (commonly
called gin trash which include the plant residues from the ginning of
cotton and consist of burrs, leaves, stems, lint, immature seeds, and
sand and/or dirt).  A total of 9 field trials should be conducted in
major cotton growing regions using representative DSMA and MSMA
formulations tested side-by-side in each trial site.  For the generation
of residue data on cotton gin by products, cotton must be harvested by
commercial equipment (stripper and mechanical picker) to provide an
adequate representation of plant residues for the ginning process. 
Residue data must be submitted for each type of harvesting equipment.

GLN 860.1520:  Processed Food/Feed

Pending submission of supporting storage stability data, the
reregistration requirements for magnitude of the residue in the
processed commodities of citrus fruit and cottonseed have been
fulfilled.  The following paragraphs present a brief summary of the
available processing data.

Citrus fruit:  In a reviewed orange processing study, residues of MSMA
and cacodylic acid were each below the analytical method’s LOQ of 0.05
ppm in/on all samples of mature oranges collected at 0-day PHI following
the last of three broadcast spray application directed to the base of
the tree using a representative MSMA formulation at 1x and 5x the
maximum label rates.  Following processing of 1x-treated oranges, no
concentration of residues was observed in any orange processed
fractions.  Following processing of 5x-treated oranges, no concentration
of residues was observed in oil and juice; however, the combined
residues of MSMA and cacodylic acid concentrated 2.6x in molasses and
3.4x in dried pulp.  The results of the orange processing study
tentatively suggest that a tolerance for the combined residues of MSMA
and cacodylic acid (expressed as As2O3) in citrus dried pulp may be
needed.  A definitive regulatory conclusion concerning the need for a
tolerance on citrus dried pulp will be made when the highest average
field trail (HAFT) residue in/on the RAC has been determined from the
requested confirmatory field study.  A tolerance for molasses need not
be proposed since this item has been deleted from Table 1 (OPPTS
860.1000) as a processed fraction of citrus fruit.

Cottonseed:  In a reviewed cottonseed processing study, the combined
residues of MSMA and cacodylic acid did not concentrate in meal and
refined oil processed from cottonseed bearing detectable residues of
MSMA and non-detectable residues of cacodylic acid.  The combined
residues, however, concentrated 2.2x to 2.5x in hulls.  The adequacy of
the established tolerance for cotton hulls cannot be established at this
time since the HAFT residue in/on the RAC (undelinted cottonseed) will
be determined when the requested confirmatory field data have been
submitted and evaluated.

GLN 860.1480:  Meat, Milk, Poultry, Eggs

The Agency has determined that no animal feeding studies are needed to
determine secondary transfer of DSMA/MSMA residues of concern in milk,
eggs, and edible tissues pending adequate cotton gin trash data.  Based
on TRR values in tissues from ruminant and poultry metabolism studies,
and on 1x feeding levels, and pending adequate cotton gin trash data,
there is no reasonable expectation of detectable MSMA residues in animal
tissues, milk, and eggs resulting from use patterns being considered for
reregistration.  Residues in livestock can be classified under Category
3 of 40 CFR §180.6(a).

GLN 860.1400:  Water, Fish, and Irrigated Crops

MAA products are not presently registered for direct use on water and
aquatic food and feed crops; therefore, no residue chemistry data are
required under these guideline topics.

GLN 860.1460:  Food Handling

MAA products are not presently registered for use in food-handling
establishments; therefore, no residue chemistry data are required under
this guideline topic.

GLN 860.1850 and 860.1900:  Confined/Field Accumulation in Rotational
Crops

The registrants have submitted a confined rotational crop study (DP
Barcode No. D206872, MRID No. 443326101) which was deemed unacceptable
because of incomplete characterization and identification of radioactive
residues in/on rotational commodities collected at several plantback
intervals.  Although inadequate, the Agency did not require the study to
be upgraded provided the Task Force did not object to a 12-month
plantback interval for all crops rotated following MSMA/DSMA
applications.  The Task Force has responded and indicated that a
12-month interval is impractical; therefore, the Agency has recommended
that limited field rotational crop studies be conducted.

GLN 860.1900 specifies that limited field trials should be conducted on
a representative crop at two sites per crop for three crop groups –
root and tuber vegetables, leafy vegetables, and small grains.

Table B.   Residue Chemistry Assessments for Reregistration of MAA.

OPPTS Guideline Numbers:  Data Requirements	Current Tolerances, ppm [40
CFR §180.289(a)]	Must Additional Data Be Submitted?	References 

860.1200:  Directions for Use	Not Applicable	Yes 	See Tables A1 and A2

860.1300:  Plant Metabolism	Not Applicable	No	42216101 , 423244013,
42391201 3, 43013401 

860.1300:  Animal Metabolism	Not Applicable	No	42009701 , 42009702 5,
42525001 , 42525002 6

860.1340:  Residue Analytical Methods

 -	Plant commodities	Not Applicable	Yes 	43279301 , 43630101 8, 43630201
8, 43769101 8, 43802501 8, 44125501 8, 44825201 

 -	Animal commodities	Not Applicable	No	43615901 

860.1360:  Multiresidue Methods	Not Applicable	No

	860.1380:  Storage Stability Data



	 -	Plant commodities	Not Applicable	Yes 	43605901, 43817101

 -	Animal commodities	N/A	No

	860.1500:  Crop Field Trials

	Citrus Fruits (Citrus spp. and Fortunella spp.) Group	0.35	Yes 
4360590112, 4368310112

Miscellaneous Commodities



 -	Cotton, seed and gin byproducts	0.7, seed	Yes 	43720701 8, 43817101
13

860.1520:  Processed Food/Feed

 -	Citrus	None established	No	44195901 , 438037018

 -	Cottonseed	0.9, hulls	No	43959801 8

860.1480:  Meat, Milk, Poultry, Eggs

 -	Milk and the Fat, Meat, and Meat Byproducts of Cattle, Goats, Hogs,
Horses, and Sheep	None established	No

	 -	Eggs and the Fat, Meat, and Meat Byproducts of Poultry	None
established	No

	860.1400:  Water, Fish, and Irrigated Crops	Not Applicable	No

	860.1460:  Food Handling	Not Applicable	No

	860.1850:  Confined Rotational Crops	Not Applicable	No	43326101 

860.1900:  Field Rotational Crops	None established	Yes 

	TOLERANCE REASSESSMENT SUMMARY			

Tolerances are established under 40 CFR §180.289(a) for residues of the
herbicide methanearsonic acid (calculated as As2O3) from application of
the disodium and monosodium salts of methanearsonic acid in/on citrus
fruit at 0.35 ppm, cottonseed at 0.7 ppm, and cottonseed hulls at 0.9
ppm. The qualitative nature of the residue in plants is adequately
understood based on acceptable metabolism studies on citrus and cotton. 
The HED Metabolism Committee (C. Swartz memo of 01/25/1995) concluded
that the residues of concern associated with the use of MSMA and DSMA
are MSMA per se and cacodylic acid expressed as As2O3.  The phrase
“calculated as As2O3" in 40 CFR §180.289(a) should be replaced with
“expressed as As2O3.”

The qualitative nature of the residue in animals is adequately
understood based on acceptable ruminant and poultry metabolism studies. 
The HED Metabolism Committee (C. Swartz memo of 01/25/1995) concluded
tolerances in meat, milk, poultry, and eggs need not be established. 
There is no reasonable expectation of detectable MSMA residues of
concern in animal commodities as a result of registered uses [Category 3
of CFR §180.6(a)].

	

A summary of tolerance reassessments for methanearsonic acid is
presented in Table C.

Tolerances Listed Under 40 CFR §180.289(a):

Citrus fruit:  The interim field trial data for citrus fruit indicate
that residues of MSMA were below the analytical method’s LOQ of 0.05
ppm in/on mature fruits harvested at 0-day PHI following the last of
three applications of DSMA and MSMA formulations at 4.9 lbs
a.i./A/application and 4.0 lbs a.i./A/application, respectively; citrus
fruit samples from treated areas bore nondetectable (<0.05 ppm) residues
of cacodylic acid except for three samples.

For tolerance reassessment, residues of MSMA and cacodylic acid are to
be converted to As2O3 equivalents (and expressed as As2O3) based on
molecular weight ratios.  The conversion factor for MSMA to As2O3
equivalents is 0.8, and the conversion factor for cacodylic acid to
As2O3 equivalents is 0.7.

											

The orange residue data conducted in Sanger, CA resulted in the highest
residues of cacodylic acid (0.11 ppm) in/on citrus fruits; residues of
MSMA in/on the same orange sample was nondetectable (<0.05 ppm).  When
individual residues of MSMA and cacodylic acid are converted to As2O3
equivalents using the above conversion factors, the combined residues
(expressed as As2O3 equivalents) are <0.12 ppm which is below the
established group tolerance of 0.35 ppm for citrus fruit.  Pending
submission of confirmatory residue decline data (to determine whether
residues of MSMA and cacodylic acid are taken up by plants at longer
PHIs) and label revisions, the tolerance for citrus fruit is reassessed
at 0.2 ppm on an interim basis.

Cottonseed:  The RAC that was analyzed in the submitted cotton field
study was delinted cottonseed as opposed to undelinted cottonseed as per
Table 1 (OPPTS 860.1000).  The adequacy of the established 0.7 ppm
tolerance level for cottonseed will be reassessed when the requested
confirmatory data for undelinted cottonseed have been received and
evaluated.  Label revisions are required to reflect the parameters of
use patterns the registrants wish to support for cotton.

Cotton hulls:  The available cottonseed processing study indicates that
the combined residues of MSMA and cacodylic acid concentrated 2.2x to
2.5x in hulls.  The adequacy of the established 0.9 ppm tolerance level
for cotton hulls cannot be reassessed at this time since the highest
average field trial (HAFT) residue in/on the RAC (undelinted cottonseed)
will be determined when the requested confirmatory field data have been
submitted and evaluated.

Tolerances to be Proposed Under 40 CFR §180.289(a):

Citrus dried pulp:  The available orange processing study indicates that
the combined residues of MSMA and cacodylic acid concentrated 3.4x in
dried pulp.  The results of the orange processing study tentatively
suggest that a tolerance for the combined residues of MSMA and cacodylic
acid (expressed as As2O3) in citrus dried pulp may be needed.  A
regulatory conclusion concerning the real need for a tolerance on citrus
dried pulp will be made when the HAFT residue in/on the RAC has been
determined from the requested confirmatory field study.

Cotton gin byproducts:  As a result of a September 1996 Agency revision
to the residue chemistry test guidelines, cotton gin by-products were
added as a recognized raw agricultural commodity of cotton.  Therefore,
a tolerance for the combined residues of MSMA and cacodylic acid
(expressed as As2O3 equivalents) should be proposed once acceptable
residue data become available.

Table C.   Tolerance Reassessment Summary for Methanearsonic Acid.

Commodity	Established Tolerance, ppm	Reassessed Tolerance, ppm	Comments

[Correct Commodity Definition]

Tolerances Listed Under 40 CFR §180.289(a)

Citrus fruit	0.35	0.2	A tentative reassessment.  Submission of
confirmatory residue decline data and label revisions are required.

Cottonseed	0.7	TBD 1	The established tolerance will be reassessed when
the requested confirmatory field trial data on undelinted cottonseed
have been received and evaluated.  Label revisions are required to
reflect the parameters of use patterns the registrants wish to support.
[Cotton, undelinted seed]

Cottonseed hulls	0.9	TBD 1	The established tolerance will be reassessed
when the HAFT residue in/on the RAC (undelinted cottonseed) has been
determined from the requested confirmatory field study.  [Cotton, hulls]

Tolerances To Be Proposed Under 40 CFR §180.289(a)

Citrus, pulp, dried	None	TBD 1	A regulatory conclusion concerning the
real need for a tolerance on citrus dried pulp will be made when the
HAFT residue in/on the RAC has been determined from the requested
confirmatory field study.

Cotton, gin byproducts	None	TBD 1	Residue data are required.

	

1TBD = To be determined.  Residue data remain outstanding.





CODEX HARMONIZATION

There are no established Codex maximum residue levels (MRLs) for MAA. 
Therefore, issues of Codex harmonization do not exist.

DIETARY EXPOSURE ASSESSMENT

No monitoring data for residues of MAA or cacodylic acid per se are
available from FDA and USDA.  The available monitoring data on total
arsenic (as As2O3) from the FDA Total Diet Study (Market Baskets 91-3
through 97-1) are limited for the food/food-forms of concern here and
are likely to significantly overestimate dietary exposure from MAA or
cacodylic acid resulting from the supported use rates of DSMA/MSMA since
they include residues of arsenic from all potential sources including
background.  Hence, all anticipated residue estimates should be based on
available field trial data for DSMA/MSMA incorporating percent of crop
treated as appropriate.  Anticipated residue estimates should be
provided for all citrus commodities as well as cotton commodities.  The
available animal metabolism and magnitude of the residue data
demonstrate that there is no reasonable expectation of finite residues
of MAA or cacodylic acid in tissues of poultry and swine from the feed
stuffs derived from raw agricultural commodities treated with DSMA/MSMA
(40 CFR §180.289(a)).

AGENCY MEMORANDA RELEVANT TO REREGISTRATION

DP Barcode:	None

Subject:	Meeting with Registrants of Cacodylic Acid, MSMA, and DSMA.

From:	S. Funk

To:	CBRS File

Dated:	12/10/1991

MRID(s):	None

CBRS No.	8998

DP Barcode:	D171625

Subject:	Reregistration of Monosodium Methanearsonate.  ISK-Biotech
Corp.  Response to Phase 4 Review of Residue Chemistry; Waiver Request.

From:	S. Funk

To:	B. Crompton

Dated:	01/13/1992

MRID(s):	None

CBRS No.	8810

DP Barcode:	D170296

Subject:	Reregistration of Disodium Methanearsonate.  Luxembourg-Pamol,
Inc.  Response to Phase 4 Review of Residue Chemistry.

From:	S. Funk

To:	B. Crompton

Dated:	01/13/1992

MRID(s):	41982001, 41976201, and 41976202

CBRS No.	8647

DP Barcode:	D168990

Subject:	Methanearsonate (MSMA/DSMA) Livestock Metabolism Studies;
Chemical No. 13803; Case No. 2395.

From:	C. Olinger

To:	B. Crompton/B. Briscoe

Dated:	04/07/1992

MRID(s):	42009701 and 42009702

CBRS No.	None

DP Barcode:	None

Subject:	Monosodium methanearsonate (MSMA).  Issues to be Presented to
the Metabolism Committee on June 8, 1992.

From:	C. Swartz

To:	The HED Metabolism Committee

Dated:	06/03/1992

MRID(s):	None

CBRS No.	None

DP Barcode:	None

Subject:	Monosodium Methanearsonate (MSMA).  Outcome of the 6/8/92
Meeting of the HED Metabolism Committee.

From:	C. Swartz

To:	The HED Metabolism Committee

Dated:	06/19/1992

MRID(s):	None

CBRS No.	None

DP Barcode:	None

Subject:	Required Number of Field Trials for Citrus Crop Group Tolerance
for MSMA and DSMA

From:	M. Metzger

To:	CB Files

Dated:	03/08/1993

MRID(s):	None

CBRS Nos.	9525, 9942, and 10245

DP Barcodes:	D175070, D178793, and D180717

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395.  Metabolism Studies in Cotton and Citrus (Lemon).

From:	C. Swartz

To:	B. Briscoe

Dated:	05/28/1993

MRID(s):	42216100, 42216101, 42324400, 42324401, 42391200, and 42391201

CBRS No.	12891

DP Barcode:	D197117

Subject:	Monosodium Methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803.  Submission to Upgrade the Cotton
Metabolism Study.

From:	C. Swartz

To:	T. Myers

Dated:	05/18/1994

MRID(s):	43013401

	

CBRS No.	None

DP Barcode:	None

Subject:	Monosodium methanearsonate (MSMA); Disodium methanearsonate
(DSMA); Cacodylic acid (CA).  Issues to be presented at the 12/19/1994
meeting of the HED Metabolism Committee.

From:	C. Swartz and B. Cropp-Kohlligian

To:	HED Metabolism Committee

Dated:	12/08/1994

MRID(s):	None

CBRS No.	13945

DP Barcode:	D204932

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803.  MAA Task Force Submission of Protocols
for Ruminant and Poultry Feeding Studies.

From:	C. Swartz

To:	V. Dietrich/R. Kendall

Dated:	01/24/1995

MRID(s):	None

CBRS No.	10836

DP Barcode:	D184346

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803.  MAA Task Force Submission to Upgrade
Ruminant and Poultry Metabolism Studies [GLN 171-4(b)].

From:	C. Swartz

To:	B. Briscoe

Dated:	01/24/1995

MRID(s):	42525001 and 42525002 CBRS No.None

DP Barcode:	None

Subject:	Monosodium methanearsonate (MSMA); Disodium methanearsonate
(DSMA); Cacodylic acid (CA).  Outcome of the 12/19/1994 meeting of the
HED Metabolism Committee.

From:	C. Swartz and B. Cropp-Kohlligian

To:	HED Metabolism Committee

Dated:	01/26/1995

MRID(s):	None

CBRS No.	15487

DP Barcode:	D214494

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395.  Guideline Ref. No. 171-4(d): Analytical methods for MSMA and
cacodylic acid in beef (fat, liver, muscle and kidney) and milk.

From:	C. Swartz

To:	M. Wilhite

Dated:	06/06/1996

MRID(s):	43615901

CBRS No.	None

DP Barcode:	D229937

Subject:	ID# GA960005 Special Local Need (Section 24(c)) Registration
for the Use of MSMA (Methanearsonic Acid and Salts) in/on Non-bearing
Pecan Orchards in the State of Georgia.

From:	C. Lewis, J. Morales, and S. Williams-Foy

To:	C. Giles-Parker/J. Bazuin

Dated:	10/17/1996

MRID(s):	None

CBRS No.	14258

DP Barcode:	D206872

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803.  MAA Task Force Submission of a
Confined  Rotational Crop Study [GRN 860.1850].

From:	C. Swartz

To:	T. Myers

Dated:	02/20/1997

MRID(s):	443326101

CBRS No.	None

DP Barcode:	D240863

Subject:	Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803.  Requirement for Limited Field
Rotational Crop Studies.

From:	C. Swartz

To:	J. Housenger and D. McNeilly

Dated:	11/18/1997

MRID(s):	None

CBRS No.	None

DP Barcode:	D242329

Subject:	Monosodium methanearsonate (MSMA).  Interim Human Health Risk
Assessment/Determination of Safety for Potential Inadvertent Residues in
the Rotational Crop Peanuts.  Chemical ID No. 013803/Reregistration Case
No. 2395.

From:	C. Swartz

To:	J. Housenger

Dated:	01/21/1998

MRID(s):	None

CBRS No.	None

DP Barcode:	D232748

Subject:	[Disodium methanearsonate (DSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013802. Citrus Processing Study].

From:	S. Kinard

To:	Tom Myer

Dated:	07/17/2000

MRID(s):	44195901

CBRS No.	None

DP Barcodes:	D205012, D205663, D214330, D215133, D217721, D219102,
D219963, D220073, D224764, D230542, and D232748

Subject:	[Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803. Analytical Methods for Quantitation of
Residues of MSMA and its Metabolite Cacodylic Acid in/on Cottonseed and
Oranges; Magnitude of the Residue in/on Cottonseed and Oranges; and
Magnitude of the Residue in the Processed Commodities of Cottonseed].

From:	S. Kinard

To:	Tom Myer

Dated:	07/20/2000

MRID(s):	43279301, 43630101, 43630201, 43720701, 43769101, 43802501,
43803701, 43959801, and 44125501

CBRS No.	None

DP Barcode:	D256117

Subject:	[Monosodium methanearsonate (MSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013803. Analytical Methods (Radiovalidation in
Cottonseed)].

From:	S. Kinard

To:	Tom Myer

Dated:	07/20/2000

MRID(s):	44825201

CBRS No.	None

DP Barcode:	D220374

Subject:	[Disodium methanearsonate (DSMA).  List B Reregistration Case
No. 2395/Chemical ID No. 013802. Magnitude of the Residue in Cotton].

From:	S. Kinard

To:	Tom Myer

Dated:	07/20/2000

MRID(s):	43817101

CBRS Nos.	15435 and 15796

DP Barcodes:	D214330 and D216740

Subject:	[Disodium methanearsonate (DSMA)/Monosodium methanearsonate
(MSMA).  List B Reregistration Case No. 2395/Chemical ID Nos. 013802 and
013803. Magnitude of the Residue in Citrus].

From:	S. Kinard

To:	Tom Myer

Dated:	07/12/2000

MRID(s):	43605901 and 43683101

MASTER RECORD IDENTIFICATION NUMBERS

References Used To Support Reregistration

42009701 Baumann, G. (1991) Metabolism of 14 Carbon-MSMA in Lactating
Goats:  Dosing, Sample Collection, Quantitation of Radioactivity and
Metabolite Analysis in Milk and Edible Tissues: Lab Project Number:
90060: RPT0059.  Unpublished study prepared by XenoBiotic

Labs, Inc.  218 p.

42009702 Baumann, G. (1991) Metabolism of 14 Carbon-MSMA in Laying Hens:
 Metabolite Analysis and Quantitation in Eggs and Tissues: Lab Project
Number: 90061: RPT0060.  Unpublished study prepared by XenoBiotic Labs,
Inc.  184 p.

42216101 O’Neal, S.; Johnson, T. (1992) Metabolic Fate and
Distribution of [carbon 14] Monosodium Methanearsonate in Cotton: Lab
Project Number: 1388: 468.  Unpublished study prepared by PTRL East,
Inc.  90 p...

42324401 O’Neal, S.; Johnson, T. (1992) Metabolic Fate and
Distribution of [carbon 14]-Monosodium Methanearsonate in Citrus
(Lemons):  Lab Project Number: 1414: 481. Unpublished study prepared by
PTRL East, Inc.; PTRL West, Inc.  96 p.

42391201 O’Neal, S.; Johnson, T. (1992) Metabolic Fate and
Distribution of [carbon 14]-Monosodium Methanearsonate in Citrus
(Lemons): Lab Project Number: 1414: 481.  Unpublished study prepared by
PTRL East, Inc., and PTRL West, Inc.  96 p.

42525001 Robinson, R. (1992) Metabolism of [14C]-MSMA in Lactating
Goats: Dosing, Sample Collection, Quantitation of Radioactivity and
Metabolite Analysis in Milk and Edible Tissues: Lab Project Number:
90060: RPT0059.  Unpublished study prepared by XenoBiotic Laboratories,
Inc.  43p.

42525002 Robinson, R. (1992) Metabolism of [14C]-MSMA in Laying Hens:
Metabolite Analysis and Quantitation in Eggs and Tissues: Lab Project
Number: 90061: RPT0060.  Unpublished study prepared by XenoBiotic
Laboratories, Inc.  55 p.

43013401 O'Neal, S.; Johnson, T. (1992) Metabolic Fate and Distribution
of (carbon 14)-Monosodium Methanearsonate in Cotton and Citrus: 
Supplemental Report to MRID No. 42216101 (Cotton) and MRID No. 42324401
(Citrus): Lab Project Number: 1388: 1414: 468.

43279301 Howard, J. (1994) Analytical Method for Residues of Monosodium
Methanearsonate and its Metabolite (Cacodylic Acid) in Citrus:  Lab
Project Number: 746: 1595.  Unpublished study prepared by PTRL East,
Inc.  42 p.

43326101 O’Neal, S.  (1994) A Confined Rotational Crop Study with
14C-Monosodium Methanearsonate (MSMA) Using Carrots (Daucus carota),
Lettuce (Lactuca sativa) and Barley (Hordeum vulagre).  Laboratory
Project ID: PTRL Project No. 603, PTRL Report No. 1546.  Unpublished
study prepared by Chemical Consultants International, Inc. for the MAA
Task Force. 184 p.

43605901 Johnson, T. (1995) Field Crop Residue Trials for MSMA on Citrus
(Raw Agricultural Commodities): Lab Project Number: 769: 1812. 
Unpublished study prepared by PTRL East, Inc.  537 p.

43615901  Howard, J. (1995) Analytical Methods for Residues of
Monosodium Methanearsonate and Its Metabolite, Cacodylic Acid, in Beef
Muscle, Liver, Kidney, Fat and Milk: Lab Project Number: 762: 1657. 
Unpublished study prepared by PTRL East, Inc.  73 p.

43630101 Howard, J. (1995) Analytical Method for Residues of Monosodium
Methanearsonate and its Metabolite (Cacodylic Acid) in Cottonseed: Lab
Project Number: 746: 1672.  Unpublished study prepared by PTRL East,
Inc.  42 p.

43630201  Nishioka, L.; Toia, R. (1995) Method Validation for Magnitude
of the Residue of Monosodium Methanearsonic Acid (MSMA) and its
Metabolite Cacodylic Acid in Citrus Fruit: Final Report: Lab Project
Number: 481W-1: 481W.  Unpublished study prepared by PTRL West, Inc.  42
p.

43683101  Johnson, T. (1995) Disodium Methanearsonate: Field Crop
Residue Trials for DSMA on Citrus (Raw Agricultural Commodities): Lab
Project Number: 769: 1820: 769-01.  Unpublished study prepared by PTRL
East, Inc.  549 p.

43720701 Johnson, T. (1995) Field Crop Residue Trials for MSMA on Cotton
(Raw Agricultural Commodities): (Final Report): Lab Project Number: 768:
1818: 768-01.  Unpublished study prepared by PTRL East, Inc.  528 p.

43769101  Howard, J. (1995) Analytical Method for Residues of Monosodium
Methanearsonate and Its Metabolite (Cacodylic Acid) in Citrus Processed
Fractions: Amended: Lab Project Number: 746: 1823. Unpublished study
prepared by PTRL East, Inc.  83 p.

43802501  Howard, J. (1995) Analytical Method for Residues of Monosodium
Methanearsonate and Its Metabolite (Cacodylic Acid) in Cotton Processed
Fractions: Lab Project Number: 746: 1828. Unpublished study prepared by
PTRL East, Inc.  72 p.

43803701 Johnson, T. (1995) Monosodium Methanearsonate: Field Crop
Residue Trials for MSMA on Citrus (Processed Commodities): Lab Project
Number: 769: 1833: 1690.  Unpublished study prepared by PTRL East, Inc. 
225 p.

43817101 Johnson, T. (1995) Field Crop Residue Trials for DSMA on Cotton
(Raw Agricultural Commodities): Lab Project Number: 768: 1838: 768-01. 
Unpublished study prepared by PTRL East, Inc.  522 p.

43959801 Johnson, T. (1995) Field Crop Residue Trials for MSMA on Cotton
(Processed Commodities): Lab Project Number: 768: 1835: 768-14. 
Unpublished study prepared by PTRL East, Inc.  183 p.

44125501 Howard, J. (1996) Radiovalidation of the Analytical Methodology
for Monosodium Methanearsonate (MSMA) and Its Metabolite, Cacodylic
Acid, in Citrus: Lab Project Number: 978: 1896: 746.  Unpublished study
prepared by PTRL East, Inc.  84 p.

44195901 Johnson, T. (1996) Disodium Methanearsonate: Field Crop Residue
Trials for DSMA on Citrus (Processed Commodities): Final Report: Lab
Project Number: 769: 1856: 769-21.

Unpublished study prepared by PTRL East, Inc.  221 p.

44825201 O'Neal, S.; Howard, J. (1998) Radiovalidation of the Analytical
Method for Monosodium Methanearsonate (MSMA) in Cottonseed: Growth and
Treatment of Cotton with (carbon-14)-MSMA and Method Validation: Lab
Project Number: 1050: 1995: 1050-1.

Unpublished study prepared by PTRL East, Inc.  142 p. {OPPTS 860.1300}	

 PAGE   

(Continued; footnotes follow).

  PAGE  3 

 PAGE   27 

(Continued; footnotes follow).

 	References were reviewed as noted.  No references were reviewed in the
MAA Phase 4 Review.

 	Label amendments are required to incorporate the parameters of use
patterns reflected in the submitted field trials.  Details of the
required label amendments are presented in the respective endnotes for
citrus fruits and cotton under GLN 860.1500 (Crop Field Trials).

 	CBRS Nos. 9525, 9942, and 10245, DP Barcodes D175070, D178793, and
D180717, 5/28/93, C. Swartz.

 	CBRS No. 12891, DP Barcode D197117, 5/18/94, C. Swartz.

 	CBRS No. 8647, DP Barcode D168990, 4/7/92, C. Olinger.

 	CBRS No. 10836, DP Barcode D184346, 1/24/95, C. Swartz.

 	Because the enforcement methods listed in PAM Volume II are
colorimetric methods, the Agency recommends that an existing GC/ECD
data-collection method be proposed as an enforcement method.  The
registrant is referred to OPPTS 860.1340 for specific requirements
concerning regulatory methods.  OPPTS 860.1340 requires that any
proposed enforcement method be subjected to an independent laboratory
validation (ILV) as per PR Notice 96-1.  If the Agency determines that
the registrant has submitted the results of a successful ILV trial by an
independent laboratory, then the method will be validated by Agency
chemists.

 	DP Barcodes D205012, D205663, D214330, D215133, D217721, D219102,
D219963, D220073, D224764, D230542, and D232748; 7/20/00; S. Kinard.

 	DP Barcode D256117, 7/20/00; S. Kinard.

 	DP Barcode D214494, 6/6/96, C. Swartz.

 	No storage stability data are available to support the storage
conditions and intervals of samples collected from the citrus and
cottons processing studies which were stored frozen for maximums of 15
and 9 months, respectively, prior to residue analysis.  The registrants
are required to submit data investigating the frozen storage stability
of residues of MSMA and cacodylic acid in the processed fractions of
citrus fruit (dried pulp, oil, and juice) and cottonseed (meal, hulls,
and refined oil) at the maximum storage intervals.

 	DP Barcodes D214330 and D216740, 7/12/00, S. Kinard.

 	DP Barcode D220374, 7/20/00, S. Kinard.

 	The Agency requires confirmatory residue decline data to determine
whether residues of MSMA and cacodylic acid are taken up by plants at
longer PHIs.  A total of 9 residue decline trials on oranges (3 trials),
lemon (3 trials), and grapefruit (3 trials) should be conducted in major
citrus growing regions.   Representative DSMA and MSMA formulations
should be tested side-by-side in each trial site.  Label  revisions are
required to reflect the parameters of use patterns for which adequate
residue data are available.  All DSMA formulations with use claims on
citrus fruits should be amended to specify a maximum single application
rate of 4.9 lb a.i/A, a maximum of three applications per growing season
or a maximum seasonal rate of 14.7 lb a.i/A, and a 0-day PHI. 
Similarly, all MSMA formulations should be amended to specify a maximum
single application rate of 4.0 lb a.i/A, a maximum of three applications
per growing season or a maximum seasonal rate of 12.0 lb a.i/A, and a
0-day PHI.

 	The Agency is requiring confirmatory field trial data on undelinted
cottonseed.  Residue data are also required for cotton gin byproducts
(commonly called gin trash which include the plant residues from the
ginning of cotton and consist of burrs, leaves, stems, lint, immature
seeds, and sand and/or dirt).  A total of 9 field trials should be
conducted in major cotton growing regions using representative DSMA and
MSMA formulations tested side-by-side in each trial site.  For the
generation of residue data on cotton gin by products, cotton must be
harvested by commercial equipment (stripper and mechanical picker) to
provide an adequate representation of plant residues for the ginning
process.  Residue data must be submitted for each type of harvesting
equipment.

	

Label revisions are required for cotton.  All DSMA and MSMA formulations
with use claims on cotton should be amended to reflect maximum seasonal
rates of either (i) 4 lb ai/A when uses include two directed spray
applications at 2 lb a.i/A/application or (ii) 3 lb a.i/A when uses
include a single topical application at 1 lb a.i/A followed by a
directed spray application at 2 lb a.i/A.  Because a PHI has not been
established for cottonseed, the registrant should propose a PHI; the
interim data suggest that a 71-day PHI would be appropriate.

 	DP Barcode D232748, 7/17/00, S. Kinard.

 	CBRS No. 14258, DP Barcode D206872, 2/20/97, C. Swartz.

 	Limited field trials should be conducted on a representative crop at
two sites per crop for three crop groups –root and tuber vegetables,
leafy vegetables, and small grains.

