Document ID: EPA-HQ-OPP-2008-0773-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-12-18T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

	OFFICE OF PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:  		08/05/2009

SUBJECT:	Prometryn.  Registration Request to Add New Use on Leaf
Petioles (Crop Subgroup 4B).  Summary of Analytical Chemistry and
Residue Data

PC Code:  080805	DP Barcodes:  D357098 & D315763

Decision Nos.:  400394 & 355879	Registration Nos.:  34704-692; 66222-15;
100-620

Petition No.:  8E7436	Regulatory Action:  Amended Section 3

Risk Assessment Type:  NA	Case No.:  0467

TXR No.:  NA	CAS No.:  7287-19-6

MRID Nos.:  44556802, 44556803, 45190601	40 CFR:  §180.222

From:		William D. Wassell, Chemist

		Risk Assessment Branch 1 (RAB1)

		Health Effects Division (HED, 7509P)

Through:		George F. Kramer, Ph.D., Senior Chemist

	RAB1/HED (7509P)

To:		William D. Wassell, Risk Assessor

		RAB1/HED (7509P)

				and

				Susan Stanton/Daniel Rosenblatt, RM 05

	Registration Division (RD; 7505P)

  SEQ CHAPTER \h \r 1 This document was originally prepared under
contract by Dynamac Corporation (1901 Research Boulevard, Suite 220;
Rockville, MD 20850).  The document has been reviewed by HED and revised
to reflect current Office of Pesticide Programs (OPP) policies.

Executive Summary

Prometryn [2,4-bis(isopropylamino)-6-methylthio-s-triazine] is a
substituted thiomethyl triazine herbicide (Group 5) registered in the
U.S. for the control of weeds in celery, cotton, dill, and pigeon peas. 
Prometryn is a List A chemical.  The Prometryn Reregistration
Eligibility Decision (RED) document was issued February 1996.  The
Product and Residue Chemistry Chapters for the Prometryn RED were issued
12/8/94.

On behalf of the Agricultural Experiment Stations of CA, NJ, and OR, the
Interregional Research Project No. 4 (IR-4) submitted a tolerance
petition in support of a request to register a new use of prometryn on
leaf petioles (crop subgroup 4B).  IR-4 initially submitted this request
in 2006 under PP#0E6174 but the petition was subsequently withdrawn. 
The petitioner now wishes to re-activate the registration request; the
initial petition has now been reassigned under PP#8E7436.

Prometryn is currently registered for use on celery, the representative
commodity of the leaf petioles subgroup.  The end-use products relevant
to this registration request are Prometryn 4L Herbicide (EPA Reg. Nos.
34704-692 and 66222-15) and Caparol 4L Herbicide (EPA Reg. No. 100-620).
 These products belong to the flowable concentrate formulation class and
contain 44.0-44.4% prometryn (equivalent to 4.0 lb ai/gal).  They are
proposed for use on leaf petiole crops as preemergence or postemergence
uses on direct-seeded crops (maximum rate of 1.6 lb ai/A), on crops
while on seedbed (maximum rate of 0.8 lb ai/A), and on transplanted
crops (maximum rate of 2.0 lb ai/A except those grown in fine-textured
soil in HI at 3.2 lb ai/A) using ground equipment.  The proposed use
pattern is essentially identical to the registered use pattern for
celery.  

In conjunction with the proposed use, IR-4 has proposed the
establishment of a tolerance for residues of prometryn in/on:

Leaf petioles subgroup	0.5 ppm

Tolerances are currently established for residues of  prometryn per se
in/on celery at 0.5 ppm, in/on carrot roots (import tolerance) at 0.1
ppm, and in/on corn grain, cotton seed, and pigeon peas at 0.25 ppm [40
CFR 180.222(a)].  Regionally restricted tolerances have been established
for prometryn residues in/on dill and parsley leaves [40 CFR
180.222(c)].

The data package associated with this registration request includes
radiovalidation data for a proposed plant enforcement method (Method No.
AG-673; MRIDs 44556802 and 44556803) and a limited field rotational crop
study (MRID 45190601).  These studies have been reviewed in separate
Data Evaluation Records.  The adequacy of these studies for the purpose
of fulfilling data requirements are summarized in this document.

The nature of the residue in plants is adequately understood for
purposes of this petition based on acceptable cotton and celery
metabolism studies.  The results of the metabolism studies support
metabolic pathways involving N-dealkylation and hydrolysis of prometryn.
 The residue of concern in plants consists of prometryn per se, which is
the currently regulated residue.

There are no livestock feedstuffs associated with the proposed uses on
the leaf petioles subgroup; therefore, no livestock metabolism data,
enforcement methods, storage stability data, or feeding studies are
required to support this action.

Adequate enforcement methodology is available to enforce the proposed
tolerances.  Prometryn is completely recovered (>80% recovery) using the
Food and Drug Administration’s (FDA’s) Multiresidue (MRM) Section
302.  In addition, an acceptable gas chromatography (GC) method with
flame-photometric detection in the sulfur mode (FPD/S), Ciba-Geigy
Method AG-559, is available for use as a single analyte confirmatory
method.  Method AG-559 was previously determined to be adequate as an
enforcement method for plant commodities pending Agency method
validation.  The Residue Chemistry Chapter of the Prometryn RED also
required radiovalidation of the method using samples from the cotton
metabolism study.    SEQ CHAPTER \h \r 1 In response, Syngenta Crop
Protection, Inc. has submitted a new enforcement method, Method AG-673,
for cotton seed and gin byproducts.  Method AG-673 is a GC method with
nitrogen-phosphorus detection (NPD) with extraction procedures similar
to those of Method AG-559.  Adequate radiovalidation data for Method
AG-673 have been submitted.  

No new crop field trial data were submitted in support of this petition.
 The proposed use of prometryn on the leaf petioles subgroup is the same
as the existing use on celery, the representative commodity of the leaf
petioles subgroup 4B.  The Residue Chemistry Chapter of the Prometryn
RED concluded that acceptable residue data were available for celery. 
However, for purposes of reregistration, information on sample storage
conditions and intervals were required from the studies (MRIDs 00034043,
00093529, and 00093548) reviewed in Prometryn Registration Standard
dated 10/14/86.  This information has not yet been submitted.  The
available crop field trial data for celery are adequate to support the
proposed use on the leaf petioles subgroup and will support a subgroup
tolerance of 0.50 ppm, pending submission of the required storage
stability information.

The nature of the residue in rotational crops is adequately understood. 
The metabolism of prometryn in rotational crops is similar to that of
the primary crops.  Acceptable field rotational crop data were
previously submitted; however, the Residue Chemistry Chapter of the
Prometryn RED required additional field rotational crop data for leafy
vegetables.  In response, Syngenta has submitted data reflecting
application to a primary crop or bare soil at 3.2 lb ai/A (~0.5x maximum
proposed seasonal rate for carrot and 1x for leaf petioles) and
plantback intervals (PBIs) of 5 and 9 months.  These data indicate that
residues of prometryn are nonquantifiable in leafy vegetables at both
PBIs, and in root crops and small grains at the 9-month PBI.  Pending
submission of supplemental storage stability data and soil
characteristics data, the available data will support the following
minimum plantback intervals (PBIs) following treatment of leaf petioles,
including celery:  a 5-month PBI for leafy vegetables, an 8-month PBI
for root crops, and a 9-month PBI for small grains and all other crops
not listed on prometryn labels.  

There are currently no established Codex maximum residue limits (MRLs)
for prometryn.  No Canadian MRLs have been established for prometryn,
although prometryn is registered for use in Canada on carrots, celery,
leeks, and peas.  These uses presumably fall under the PMRA General MRL
of 0.1 mg/kg.  Mexican MRLs have been established for residues of
prometryn in/on corn, cotton, and pea, at 0.25 ppm, and celery at 0.5
ppm.  The Mexican MRLs are harmonized with the U.S. tolerances.  The
Canadian MRLs for residues in carrot, celery, and peas are not
harmonized as the submitted residue data for these commodities showed
that a tolerance level higher than that established by Canada is
required in the U.S.

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

Pending submission of a revised Section B (see requirements under
Directions for Use) and a revised Section F (see requirements under
Proposed Tolerances), there are no residue chemistry issues that would
preclude granting a conditional registration for the requested use of
prometryn on the leaf petioles subgroup or establishment of a permanent
tolerance for residues of prometryn as follows:

Leaf petioles subgroup 4B	0.50 ppm

Concomitant with the establishment of a tolerance for residues of
prometryn in/on the leaf petioles subgroup, HED recommends the
revocation of the established tolerance for prometryn in/on celery.

A human-health risk assessment is forthcoming.

860.1200 Directions for Use

Based on the results of limited field rotational crop studies, the
product labels for Prometryne 4L Herbicide (EPA Reg. Nos. 34704-692 and
66222-15) and Caparol 4L Herbicide (EPA Reg. No. 100-620) should be
amended to specify the following minimum rotational crop restrictions
following applications to celery and the leaf petioles crop subgroup:  a
5-month PBI for leafy vegetables, an 8-month PBI for root crops, and a
9-month PBI for small grains and all other crops not listed on prometryn
labels.

860.1550 Proposed Tolerances

The proposed tolerance should be revised to reflect the correct
commodity definition:  “Leaf petioles subgroup 4B”.  

HED recommends that conversion of conditional registration to
unconditional registration for the requested uses on leaf petioles upon
adequate resolution data gaps listed above as well as upon submission of
the outstanding residue chemistry data pertaining to storage stability
and field accumulation in rotational crops.

860.1380 Storage Stability

In the Residue Chemistry Chapter of the Prometryn RED, HED concluded
that the requirements for storage stability data were not fully
satisfied for reregistration because information regarding sample
storage intervals and conditions was needed for celery and cotton seed
samples from studies reviewed in the 10/86 Prometryn Registration
Standard.  These data remain outstanding.  To support the proposed use
on the leaf petioles subgroup, information on sample storage conditions
and intervals is required from the celery studies (MRIDs 00034043,
00093529, and 00093548).  If the storage intervals for celery samples
from these studies exceeded 37 months, or if storage conditions differed
from those represented in the storage stability studies, additional
storage stability data or new crop field trials may be required.

To support the field rotational crop study (MRID 45190601), storage
stability data are required reflecting the stability of residues of
prometryn in samples of beet root and wheat hay, or straw stored frozen
for up to 20-24 months.

860.1900 Field Accumulation in Rotational Crops

Additional information is required concerning the soil characteristics
and sample harvest and handling procedures at the CA and MS sites for
the study reported in MRID 45190601.

Background

The chemical structure and nomenclature of prometryn and the triazine
impurities GS-11354 and GS-26831 are presented in Table 1.  The
physicochemical properties of the technical grade of prometryn are
presented in Table 2.

Table 1.  Prometryn Nomenclature.

Chemical structure	

Common name	Prometryn

Company experimental name	G-34161

IUPAC name	N,N'-diisopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine

CAS name
N,N'-bis(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine 

CAS registry number	7287-19-6

End-use product (EP)	Caparol® 4L (4 lb/gal FlC; EPA Reg. No. 100-620)

Prometryn 4L Herbicide (4 lb/gal FlC; EPA Reg. No. 66222-15)

Triazine Impurity

 

2-amino-4-iospropylamino-6-methylthio-s-triazine

Triazine impurity

 

2,4-bis-amino-6-methylthio-s-triazine



Table 2.	   Physicochemical Properties of Prometryn.

Parameter	Value	Reference

Melting range	118-120(C	DP# 207139, 12/8/94, C. Swartz

pH	6.7 at 20ºC (saturated solution)	RCB# 2907, 12/4/87, G. Makhijani

Density	1.16 g/mL at 20ºC

	Water solubility	33 ppm at 20ºC	DP# 207139, 12/8/94, C. Swartz

Solvent solubility	10-30 g/100 mL in acetone,

dichloromethane, methanol, 

octanol, and toluene at 20ºC

	Vapor pressure	8.54 x 10-7 mm Hg at 25ºC	DP#s 196116 & 196123,
4/25/94, K. Dockter

Dissociation constant, pKa	4.09 at 20ºC	RCB# 2907, 12/4/87, G.
Makhijani

Octanol/water partition coefficient	KOW = 2140 at 25ºC	DP#s 196116 &
196123, 4/25/94, K. Dockter

UV/visible absorption spectrum	Not available

	

860.1200  Directions for Use

Prometryn is currently registered for use on celery.  The 4 lb/gal FlC
formulations (EPA Reg. Nos. 34704-692 and 100-620) are registered for
use on celery at various growth stages:  (i) on seed beds,
postemergence, at 0.6-0.8 lb ai/A; (ii) on direct seeded-crops, pre- or
post-emergence, at 0.8-1.6 lb ai/A; and (iii) on transplanted crops,
postemergence, at 1.0-3.2 lb ai/A.  IR-4 is now proposing tolerances and
use directions for leaf petioles (crop subgroup 4B).  

A list of the relevant end-use products proposed for use on crop
subgroup 4B is presented in Table 3A.  A summary of the proposed use
pattern is presented in Table 3B.  The proposed use pattern is
essentially identical to the registered use pattern for celery.

Table 3A.  Summary of Proposed End-Use Products.

Trade Name	EPA Reg. No.	ai (% of formulation)	Formulation Type	Target
Crops	Target Pests	Label Date

Prometryne 4L Herbicide	34704-692	44.4 1	FlC	Leaf petioles subgroup
including cardoon, celery, Chinese celery, celtuce, Florence fennel,
rhubarb, and Swiss chard	Most annual broadleaf weeds and grasses 
Undated.   Info obtained from Section B.

Prometryn 4L Herbicide	66222-15	44.0 1	FlC	Leaf petioles crop group 4B
(cardoon, celery, Chinese celery, celtuce, fennel, rhubarb, and Swiss
chard)	Most annual broadleaf weeds and grasses 	Undated draft label

Caparol 4L Herbicide	100-620	44.4 1	FlC	Leaf petioles crop subgroup 4B
(except rhubarb)	Most annual broadleaf weeds and grasses	Undated draft
label

Rhubarb

1  Equivalent to 4 lb ai/gal.

Table 3B.   Summary of Proposed Directions for Use of Prometryn on Leaf
Petioles (Crop Subgroup 4B).

Application Timing and Rate1	Max. No. Applic. per Season	Max. Seasonal
Applic. Rate

(lb ai/A)	PHI

(days)	Use Directions and other Limitations

(i.e. grazing, type of application/equipment, plantback interval, other)

Prometryne 4L Herbicide (EPA Reg. No. 34704-692)

For direct-seeded crops:

Preemergence

1.2-1.6 lb ai/A	1	1.6

(Implied)	Not specified

(NS)	Application to be made in a minimum 20 gallons of water per acre
(GPA) using ground equipment.  Apply as a broadcast treatment at
planting or shortly after planting before crop emerges.  Not to be used
on sand or loamy sand soils.

For transplanted crops:

Postemergence

1.0-1.6 lb ai/A (coarse soils)

1.6-2.0 lb ai/A (fine soils)	1	2.0

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply over the crop during the 2- to 6-week period after
planting.  

No rotational crop restrictions are included in Section B.  Rotational
crop restrictions, specific to cotton use only, are listed on the
registered label.

Prometryn 4L Herbicide (EPA Reg. No. 66622-15)

For seedbeds in FL:

Postemergence

0.6-0.8 lb ai/A	1	0.8

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply as a broadcast treatment after the crop has 2-5 true
leaves and only after seedbed covers have been removed for at least one
week.  

For direct-seeded crops in CA:

Preemergence or postemergence

1.2-1.6 lb ai/A (preemergence)

0.8-1.0 lb ai/A (postemergence)	12	1.0

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply preemergence at planting or shortly after planting
before crop emerges or apply postemergence after the crop has 2-5
leaves.  To avoid injury to direct-seeded crops:  (1) Make either one
preemergence or one postemergence application (not both) per crop.  (2)
Do not use on sand or loamy sand.  (3) Do not apply if crop is under
water stress.  (4) Do not apply postemergence treatments of Caparol 4L
with other pesticides.  Apply only after foliar applications of other
pesticides are dry.  (5) Do not apply within two weeks of an herbicidal
oil, such as ‘carrot’ oil.

For transplanted crops:

Postemergence

0.8-1.6 lb ai/A for sandy or

    muck soils in FL

1.0-1.6 lb ai/A for coarse-

    textured soils in CA and TX

1.6-2.0 lb ai/A for fine-

    textured soils in CA and TX

1.0-2.0 lb ai/A for fine-

    textured or muck soils in

    MI and OH

1.6-2.0 lb ai/A for fine-

    textured soils in WI

1.6-2.4 lb ai/A for coarse-

    textured soils in HI

2.4-3.2 lb ai/A for fine-

    Textured soils in HI	1	2.0 in CA, FL, MI, OH, TX, WI

(Implied)

3.2 in HI

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply during the 2- to 6-week period after transplanting.

The following rotational crop restrictions appear on the draft label: 
“The following crops may be seeded 5 months after applying no more
than 2.0 lb ai/A on leaf petioles:  cabbage, corn, cotton, peas, and
leaf petioles.  Onions and red beets may not be planted within 8 months
of applying prometryn.”

Caparol 4L Herbicide (EPA Reg. No. 100-620)

For seedbeds:

Postemergence

0.6-0.8 lb ai/A

	1	0.8

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply as a broadcast treatment after the crop has 2-5 true
leaves and only after seedbed covers have been removed for at least one
week.  

For direct-seeded crops:

Preemergence or postemergence

1.2-1.6 lb ai/A (preemergence)

0.8-1.0 lb ai/A (postemergence)

	1	1.6

(Implied)	NS	Application to be made in a minimum 20 GPA using ground
equipment.  Apply preemergence at planting or shortly after planting
before crop emerges or apply postemergence after crop has 2-5 leaves. 
To avoid injury to direct-seeded crops:  (1) Make either one
preemergence or one postemergence application (not both) per crop.  (2)
Do not use on sand or loamy sand.  (3) Do not apply if crop is under
water stress.  (4) Do not apply postemergence treatments of Caparol 4L
with other pesticides.  Apply only after foliar applications of other
pesticides are dry.  (5) Do not apply within two weeks of an herbicidal
oil, such as ‘carrot’ oil.

For transplanted crops:

Postemergence

0.8-1.6 lb ai/A for sandy or

    muck soils in FL

1.0-1.6 lb ai/A for coarse-

    textured soils in CA and TX

1.6-2.0 lb ai/A for fine-

    textured soils in CA and TX

1.0-2.0 lb ai/A for fine-

    textured or muck soils in

    MI and OH

1.6-2.0 lb ai/A for fine-

    Textured soils in WI	12	2.0

(Implied)	40	Application to be made in a minimum 20 GPA using ground
equipment.  Apply during the 2- to 6-week period after transplanting.

The following rotational crop restrictions appear on the draft label: 
“The following crops may be seeded 5 months after applying no more
than 2.0 lb ai/A on the crop:  cabbage, celery, corn, cotton, dill
fennel, okra, and peas.  Onions and red beets may not be planted within
8 months of applying prometryn.  All other crops may be planted 12
months after application.”

 

Separate use directions for Rhubarb:  One broadcast application when
plants are dormant before leaves have emerged from the crown at 1-1.6 lb
ai/A (coarse-textured soils) or 1.6-2.0 lb ai/A (fine-textured soils). 
Application is to be made in a minimum 20 GPA using ground equipment.  A
40-day PHI is specified.

1   Use of lower rates on coarse-textured soils low in organic matter
and higher rates on fine-textured soils high in organic matter is
recommended.

2   For application to transplanted crops using Caparol 4L Herbicide
(EPA Reg. No. 100-620), the label specifies that a single or split
application may be made over the crop as long as the maximum seasonal
rate does not exceed 2.0 lb ai/A.

Conclusions:  The submitted use directions are adequate to allow
evaluation of the requested use and the available crop field trial data.
 The proposed uses of the 4 lb/gal FlC products on the leaf petioles
subgroup (including the separate rhubarb use directions on the Caparol
4L Herbicide label) fall within the parameters of the registered uses
for seedbed, direct-seeded, and transplant application to celery.  

Based on the results of limited field rotational crop studies, the
product labels for Prometryn 4L Herbicide (EPA Reg. Nos. 34704-692 and
66222-15) and Caparol 4L Herbicide (EPA Reg. No. 100-620) must be
amended to specify the following minimum rotational crop restrictions
following applications to celery and the leaf petioles crop subgroup:  a
5-month PBI for leafy vegetables, an 8-month PBI for root crops, and a
9-month PBI for small grains and all other crops not listed on prometryn
labels.   

860.1300 Nature of the Residue – Plants

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

The qualitative nature of the residue in plants is adequately understood
for registered uses based on acceptable cotton and celery metabolism
studies.  The results of the metabolism studies support metabolic
pathways involving N-dealkylation and hydrolysis of prometryn.  The
Agency previously determined that the residue of concern in plants
consists of the parent, prometryn per se, which is the currently
regulated residue.  

Conclusions:  For the purposes of this petition, HED concludes that
prometryn per se is the residue of concern for tolerance enforcement and
risk assessment purposes in leaf petioles.

860.1300 Nature of the Residue - Livestock

There are no livestock feed items associated with the proposed uses;
therefore, data requirements for livestock metabolism data are not
relevant to this tolerance petition.

860.1340 Residue Analytical Methods

DER Reference:  44556802.der.doc (includes review of MRID 44556803)

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

Enforcement methods:    SEQ CHAPTER \h \r 1  Adequate enforcement
methodology is available to enforce the proposed tolerances.  Prometryn
is completely recovered (>80% recovery) using FDA’s Multiresidue
Section 302.

In addition, an acceptable GC/FPD/S method, Ciba-Geigy Method AG-559, is
available for use as a single analyte confirmatory method.  Method
AG-559 has undergone a successful independent laboratory validation and
was radiovalidated using samples from the celery metabolism study;
however, these samples contained no detectable residues of prometryn. 
HED previously concluded that Method AG-559 is acceptable for
enforcement purposes, pending completion of a successful Agency method
validation trial.  The Residue Chemistry Chapter of the Prometryn RED
also required radiovalidation of the method using samples from the
cotton metabolism study.

MRIDs 44556802 and 44556803 (44556802.der.doc):  In response to the
radiovalidation data requirements, Syngenta Crop Protection, Inc. has
submitted a method description and validation data for a GC/NPD method,
Method No. AG-673, for the determination of prometryn residues in/on
cotton matrices (MRID 44556802).  The method determines residues of
prometryn and its metabolites GS-11354 and GS-26831 in cotton seed and
gin byproducts.  

Briefly, samples of homogenized cotton seed and gin byproducts are
extracted with methanol/water at reflux, and the extract is concentrated
and acidified prior to cleanup by C-18 solid-phase extraction (SPE) and
then strong cation exchange SPE.  The extract is then basified,
partitioned into dichloromethane/ethyl acetate, and dissolved in
toluene/methanol for analysis by GC/NPD.  The validated LOQ is 0.05 ppm
for each analyte in each commodity.  

The method was adequately validated using samples of cotton seed and gin
byproducts fortified with a mixed standard of prometryn and metabolites
at 0.05, 0.1, and 1.0 ppm each.  Recoveries of prometryn, GS-11364, and
GS-26831 ranged 76-109%, 74-110%, and 76-103%, respectively, from cotton
seed, and ranged 70-106%, 82-111%, and 80-110%, respectively, from
samples of cotton gin byproducts.

Method AG-673 specifies that analyte residues may be confirmed by
equipping the GC system with a flame photometric detector, as described
for Method AG-559.  The extraction procedures of Method AG-673 are
similar to those of AG-559.

Adequate radiovalidation data were submitted demonstrating that Method
AG-673 adequately extracts aged residues of prometryn and GS-11364 from
samples of cotton gin byproducts (MRID 44556803).  Although no residues
of prometryn, GS-11364, or GS-26831 were detected in the cotton seed
samples, and no residues of GS-26831 were detected in the cotton gin
byproducts samples used for radiovalidation, no residues of these
compounds were found in cotton seed samples in the cotton metabolism
study (DP# 202698, 9/14/94, C. Swartz), and the levels of GS-26831 found
in cotton stalk samples in the cotton metabolism study were below the
LOQ of Method AG-673.  

The registrant has proposed Method AG-673 for enforcement purposes for
cotton seed and gin byproducts.  No independent laboratory validation
(ILV) data were submitted for Method AG-673; however, adequate ILV data
have been submitted previously for Method AG-559 (DP# 160100, 5/24/91,
E. Zager).  HED will not require ILV data for Method AG-673.  

Data-collection methods:  The previously reviewed celery crop field
trial data were collected using either a spectrophotometric method or GC
methods using microcoulometric, thermionic, or FPD/S detectors.  The
registrant provided adequate method validation data to verify the
suitability of these methods for data collection.

Conclusions:  The submitted residue analytical methods data are adequate
to satisfy data requirements for the subject action.  Acceptable
enforcement methodology is available for tolerance enforcement purposes
for the proposed use, and adequate methods were used for data collection
in the submitted field trial studies.

860.1360 Multiresidue Methods

The FDA PESTDATA database (dated 06/05) indicates that prometryn is
completely recovered (>80% recovery) using the MRM method Pesticide
Analytical Manual (PAM), Vol. I Section 302 and partially recovered
(22-87% recovery) using Sections 303 and 304, with the recovery varying
depending upon the choice of Florisil system used.

860.1380 Storage Stability

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

Storage stability studies have been conducted using fortified samples of
celery, cotton seed, fresh and dried parsley, pigeon peas, and sesame
seed.  Residues of prometryn and its metabolites GS-11354 and GS-26831
were found to be stable in/on cotton seed and celery samples stored
frozen at -20°C for up to 37 months, in/on fresh and dried parsley
samples stored frozen for up to 21.7 months, and in/on sesame seed
stored frozen for up to 14 months.  Residues of prometryn per se were
found to be stable in/on pigeon peas stored at -12°C for up to 42 days.

Samples of rotational crop commodities from the submitted field
rotational crop study were stored frozen at the field sites (temperature
unspecified) and analytical laboratory (~-20 °C) prior to analysis. 
The maximum storage intervals from harvest to analysis were 487 days
(16.0 months) for spinach, 615-642 days (20.2-21.1 months) for beet
roots and tops, and 657-717 days (21.6-23.6 months) for wheat forage,
hay, straw, and grain.  No storage stability data were submitted in
support of the rotational crop study.

Conclusions:  In the Residue Chemistry Chapter of the Prometryn RED, HED
concluded that the requirements for storage stability data were not
fully satisfied for reregistration because information regarding sample
storage intervals and conditions was needed for celery and cotton seed
samples from studies reviewed in the 10/86 Residue Chemistry Chapter. 
These data remain outstanding.  To support the proposed use on the leaf
petioles subgroup, information on sample storage conditions and
intervals is required from the celery crop field trials studies (MRIDs
00034043, 00093529, and 00093548) reviewed in the Residue Chemistry
Chapter.  If the storage intervals for celery samples from these studies
exceeded 37 months, or if storage conditions differed from those
represented in the storage stability studies, additional storage
stability data or new crop field trials may be required.

The available storage stability data for celery, cotton seed, and fresh
parsley are acceptable to support the storage intervals and conditions
of rotational spinach and beet tops (parsley and celery data) and wheat
grain (cotton seed data) from the submitted field rotational crop study.
 No storage stability data are available to support the storage
intervals and conditions for rotated beet roots or wheat, hay, or straw.
 Storage stability data are required reflecting the stability of
residues of prometryn in samples of beet root and wheat hay, or straw
stored frozen for up to 20-24 months.

860.1480 Meat, Milk, Poultry, and Eggs

There are no livestock feedstuffs associated with the proposed uses on
the leaf petioles subgroup.  Therefore, data requirements pertaining to
meat, milk, poultry, and eggs are not relevant to this tolerance
petition. 

860.1500 Crop Field Trials

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

No new crop field trial data were submitted in support of this petition.
 IR-4 stated that the proposed use of prometryn on the leaf petioles
subgroup is the same as the existing use on celery.

The Residue Chemistry Chapter of the Prometryn RED concluded that
acceptable residue data were available for celery.  However, for
purposes of reregistration, information on sample storage conditions and
intervals was required from the studies (MRIDs 00034043, 00093529, and
00093548) reviewed in the 10/86 Prometryn Registration Standard.  This
information has not yet been submitted.  If sample storage intervals
exceeded 37 months, or if storage conditions differed from those in the
supporting storage stability studies, additional storage stability data
or new residue field trials may be required.

The available crop field trial data for celery were summarized in the
Prometryn Residue Chemistry Chapter of the Registration Standard (10/86)
and the Prometryn Residue Chemistry Reregistration Standard Update
(5/24/91).  In four trials in HI (Zone 13), residues of prometryn were
<0.04-0.35 ppm in/on celery harvested 74-91 days following a single
broadcast application of a 50% or 80% wettable-powder (WP) formulation
at 2-4.8 lb ai/A (0.6-1.5x the maximum proposed rate to leaf petioles in
HI).  Residues of prometryn were <0.04-0.37 ppm in/on celery grown in FL
(seven trials; Zone 3) and harvested 50-167 days following seedbed or
one to two posttransplant applications of an 80% WP formulation at 1-4
lb ai/A (0.5-2x the maximum proposed rate to leaf petioles except in
HI).  In ten trials in CA, prometryn residues were <0.04-0.11 ppm in/on
celery harvested 51-158 days following preemergence, postemergence,
and/or posttransplant applications of a 50% or 80% WP formulation at
1-16 lb ai/A (0.5x-8x the maximum proposed rate to leaf petioles except
HI).  In seven trials conducted in CA (2), FL (2), MI (2; Zone 5), and
MN (1; Zone 5), prometryn residues were <0.02-0.19 ppm in/on celery
samples harvested 37-70 days following a single postplant application of
a 4 lb/gal emulsifiable concentrate (EC) formulation at 3.2-6.4 lb ai/A
(1.6-3.2x the maximum proposed rate for leaf petioles except in HI).  In
studies using the EC formulation, celery samples were also analyzed for
residues of prometryn metabolites GS-11354 and GS-26831, which were each
<0.02 ppm in/on all samples.

Conclusions:  The available crop field trial data for celery are
adequate to support the proposed use on the leaf petioles subgroup,
pending submission of the required storage stability information.  The
data reflect the proposed use patterns for prometryn on the leaf
petioles subgroup, and the number and location of field trials exceed
the requirements of OPPTS 860.1500 for celery as the representative
commodity of the subgroup.

The available data will support the proposed tolerance of 0.50 ppm for
residues of prometryn in/on leaf petioles subgroup 4B.

860.1520 Processed Food and Feed

HED does not require residue data for any processed commodities
associated with the leaf petioles subgroup.  Therefore, data
requirements for processed food and feed are not relevant to this
tolerance petition.

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

Analytical standards for prometryn are currently available [expiration
1/1/2010 (Syngenta) and 5/1/2011 (MANA)] in the EPA National Pesticide
Standards Repository (personal communication with Dallas Wright, ACB,
12/18/08).  Analytical reference standards of prometryn should be
replenished as requested by the Repository.  The reference standards
should be sent to the Analytical Chemistry Lab, which is located at Fort
Meade, to the attention of Theresa Cole at the following address:

	USEPA

	National Pesticide Standards Repository/Analytical Chemistry Branch/OPP

	701 Mapes Road

	Fort George G. Meade, MD  20755-5350

(Note that the mail will be returned if the extended zip code is not
used.)

860.1850 Confined Accumulation in Rotational Crops

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

The nature of the residue in rotational crops is adequately understood. 
The metabolism of prometryn in rotational crops is similar to that of
the primary crops and involves dealkylation, oxidation, hydroxylation,
deamination, and conjugation.  The residues of concern in rotational
crops are prometryn.

Ring-labeled [14C]prometryn was applied to test sites containing sandy
loam soil in MS and CA.  At the MS site, prometryn was applied at 2.8 lb
ai/A at the time of planting to a primary crop of cotton.  Further
applications were made when the plants were 3-6" tall (0.65 lb ai/A) and
12-18" tall (1.6 lb ai/A) for a total application rate of 5.0 lb ai/A. 
At the CA site, a single application of prometryn was made at 3.2 lb
ai/A when the primary crop, celery, was immature.  After harvesting the
primary crop, the rotational crops were planted:  lettuce was planted
111 and 229 (MS) and 193 (CA) days after the final prometryn treatment
(DAT), wheat was planted 111 (MS) and 350 DAT (CA), soybeans were
planted 193 (CA) and 328 DAT (MS), and table beets were planted 193 (CA)
and 249 DAT (MS).

The total radioactive residues (TRR) in all RACs from all PBIs at both
sites exceeded 0.01 ppm.  The TRR values ranged 0.030-0.447 ppm.  The
following metabolites were identified in the rotational crops: 
prometryn, GS-11957, GS-17794, MCO-III-25, MCO-IV-34, GS-11526 and its
side chain alcohol, along with unidentified acetyl and sugar conjugates
of triazines.  Although 14C-residues were not quantified, greater than
50% of the TRR appeared to consist of triazine-containing metabolites. 
Based on these data, the registrant conducted limited field rotational
crop studies.

860.1900 Field Accumulation in Rotational Crops

DER Reference:  45190601.der.doc

Residue Chemistry Memo:  Residue Chemistry Chapter of the Prometryn RED,
DP# 207139, 12/8/94, C. Swartz

Residue Chemistry Memo:  DP#s D191118 and D191119, 9/3/93, G. Kramer

Residue Chemistry Memo:  DP# 207717, 12/5/94, C. Swartz

Limited and extensive rotational crop studies were previously submitted
for prometryn.  The available studies include a limited rotational crop
study (DP#s D191118 & 191119) reflecting application to a primary crop
or bare soil at 5-12 lb ai/A, with rotational crops planted at PBIs of
3-4 and 7-9 months, and an extensive rotational crop study (DP# 207717)
on small grains reflecting application at 5-6 lb ai/A and a 3- to
6-month PBI.  

Based on these studies, the Residue Chemistry Chapter of the Prometryn
RED recommended rotational crop restrictions:  8-month PBI for root
crops and a 3-month PBI for small grains with establishment of
tolerances for residues in rotated small grain commodities.  The
requested tolerances for small grains have not been established. 
Additional limited rotational crop data were also required for leafy
vegetables reflecting either limited field trials conducted with lettuce
at a 12-month PBI or extensive field trials with representative leafy
vegetables at an 8-month PBI.

MRID 45190601 (45190601.der.doc):  In response to the Prometryn RED,
dated 3/16/95, Syngenta Crop Protection, Inc. has submitted limited
field rotational data.  A total of five rotational crop trials on the
representative crops table beet (root vegetable), spinach (leafy
vegetable), and wheat (cereal grain) were conducted during the 1996-1998
growing seasons.  Trials were conducted at two trial sites, in MS (Zone
4, two trials) and CA (Zone 10, 3 trials), for each crop.  The 4 lb/gal
EC formulation of prometryn was applied to two separate treatment plots
for each crop as four or two applications.  A primary crop of cotton was
planted at two of the CA trials; applications for remaining crops were
made to bare soil.  The first treatment plot (Treatment 2) received a
incorporated application at planting at 0.3 lb ai/A followed by two
postemergence directed hoe spray applications at 0.65 lb
ai/A/application and one directed application at layby at 1.6 lb ai/A,
for a total application rate of 3.2 lb ai/A (1x maximum proposed rate to
leaf petioles).  The first postemergence application was made ~42 days
following the preemergence application, and the retreatment interval
(RTI) for the postemergence applications was ~14 days.  The second
treatment plot (Treatment 3) received only the second postemergence hoe
spray application and the layby application for a total application rate
of 2.25 lb ai/A (0.7x the maximum proposed rate to leaf petioles).  We
note that regardless of whether applications were made to cotton or to
bare ground, the application timing was reported in terms of cotton
growth stages. 

No information pertaining to the harvest or destruction of cotton was
provided.  Rotational crops were planted 148-153 (~5 months) and 272-276
days (~9 months) after final application at each treatment plot, and
samples of spinach, beet roots and tops, and wheat forage, hay, grain,
and straw were collected at the appropriate crop growth stage or at
maturity.

Samples of rotational crop commodities were analyzed for residues of
prometryn per se using GC/FPD/S Method AG-559.  A GC equipped with a
mass spectrum detector (MS) method was used to confirm residue results
for samples in which interferences were encountered.  The registrant
used the LLMV of 0.02 ppm as the LOQ.  Acceptable concurrent recoveries
were obtained from samples of untreated spinach, beet roots and tops,
and wheat forage, straw, and grain fortified with prometryn at 0.02,
0.05, and/or 0.5 ppm.  

At the 5-month PBI, quantifiable residues were reported in samples of
beet tops and wheat forage, hay, and straw from two CA trials at:  0.028
ppm in one sample each of beet tops following Treatments 2 (total
application rate of 3.2 lb ai/A) and 3 (total application rate of 2.25
lb ai/A); 0.033-0.19 ppm in forage (6 of 8 samples) following Treatments
2 and 3; 0.043 and 0.064 ppm in hay following Treatment 3; and 0.029 and
0.032 ppm in straw following Treatment 3.  We note that residues in
rotational crops planted following Treatment 3, which had the lower
total application rate, were not lower than residues in rotational crops
planted following Treatment 2.  Residues in remaining samples of
spinach, beet tops and roots, and wheat forage, hay, straw, and grain
from the 5-month PBI were below the LOQ.  Residues in all rotational
crop samples from the 9-month PBI were below the LOQ.

Two trial sites, in MS (Zone 4) and CA (Zone 10), were used for each
crop.  The registrant did not provide soil characteristics data for
either site and did not provide any information concerning sample
harvest or handling procedures at the field sites.  These data are
required to support the field rotational crop study.

Conclusions:  Adequate field rotational crop data are available to
support the proposed use on the leaf petioles crop subgroup, pending
submission of additional information concerning the soil characteristics
and sample harvest and handling procedures at the CA and MS sites, and
supporting storage stability data reflecting the stability of residues
of prometryn in samples of beet root and wheat forage, hay or straw
stored frozen for up to 20-24 months.  

The available data will support the following minimum PBIs following
treatment of leaf petioles, including celery:  a 5-month PBI for leafy
vegetables and an 8-month PBI for root crops.  The Residue Chemistry
Chapter previously concluded that a 3-month PBI would be appropriate for
small grains provided rotational crop tolerances were proposed for the
forage, hay, and straw of small grains.  These tolerances have not been
proposed.  Until these tolerances have been established, a 9-month PBI
must be established for small grains and all other crops not listed on
prometryn labels rotated after leaf petioles.

HED notes that use of prometryn is registered on certain crops at rates
higher than 3.2 lb ai/A, including use on cotton at up to 6 lb ai/A. 
For these crops, the available data will support the following minimum
plantback restrictions for crops not listed on prometryn labels:  (1)
Following maximum application to any primary crop at up to 3.2 lb ai/A: 
a 5-month PBI for leafy vegetables, an 8-month PBI for root crops, and a
9-month PBI for small grains and all other crops.  (2) Following
application at rates higher than 3.2 lb ai/A and up to 6.0 lb ai/A:  an
8-month PBI for root crops; rotation to all other crops is prohibited.

860.1550 Proposed Tolerances

HED has determined that the residue of concern for tolerance enforcement
in primary and rotated crops is prometryn per se.  The tolerance
expression proposed in this petition is appropriate.

The available crop field trial data for celery will support a tolerance
of 0.50 ppm for prometryn residues in/on the leaf petioles subgroup. 
Concomitant with the establishment of a tolerance for the leaf petioles
subgroup, we recommend the revocation of the established tolerance for
celery.

There are currently no established Codex MRLs for prometryn.  No
Canadian MRLs have been established for prometryn, although prometryn is
registered for use in Canada on carrots, celery, leeks, and peas.  These
uses presumably fall under the PMRA General MRL of 0.1 mg/kg.
[Regulation B.15.002(1) of the Canadian Food and Drugs Regulations (FDR)
establishes 0.1 ppm as the General Maximum Residue Limit.  This
regulation states that a food is adulterated if it contains residues of
a pesticide at a level greater than 0.1 ppm unless a specific MRL has
been established in Table II, Division 15 of the FDR.  PMRA is in the
process of revoking this general MRL and establishing individual
tolerances.]  Mexican MRLs have been established for residues of
prometryn in/on corn, cotton, and pea, at 0.25 ppm, and celery at 0.5
ppm.  The Mexican MRLs are harmonized with the U.S. tolerances.  The
Canadian MRLs for residues in carrot, celery, and peas are not
harmonized as the submitted residue data for these commodities showed
that a tolerance level higher than that established by Canada is
required in the U.S.

A summary of tolerance assessment is presented in Table 4.  The proposed
tolerance should be revised to reflect the correct commodity definition
as specified in Table 4.

Table 4.  Tolerance Summary for Prometryn.

Commodity	Proposed Tolerance (ppm)	HED-Recommended Tolerance (ppm)
Comments;

Correct Commodity Definition

Tolerance to be established under 40 CFR §180.222 (c):

Leaf Petioles Subgroup	0.5	0.50	Leaf petioles subgroup 4B

References

DP#:		191118 and 191119

Subject:	ID# 080805. Review of rotational crop studies of prometryn. 
Case 819250. CBTS# 11852

From:		G. Kramer

To:		L. Propst and M. Fiol

Dated:		9/3/93

MRIDs:	42081601 and 41901202

DP#:		207717

Subject:	Prometryn.  List A Reregistration Case No. 0467/Chemical ID No.
080805. Ciba-Geigy Submission of Data to Satisfy Guideline Requirements
165-2, Field Rotational Crop and 171-4(e), Storage Stability.

From:		C. Swartz

To:		L. Propst

Dated:		12/5/94

MRID(s):	43370404 and 43370405

DP#:		207139

Subject:	Prometryn.  List A Reregistration Case No. 0467/Chemical ID No.
080805.  Product and Residue Chemistry Considerations to be Included in
the HED Chapter of the Reregistration Eligibility Decision Document. 
CBRS No. 14299.  

From: 		C. Swartz

To:		D. Edwards

Dated:		12/8/94

MRID(s): 	None

RDI: RAB1:  06/17/2009

Petition Number:  PP#8E7436

DP Number:  357098

PC Code:  080805

WDWassell:S10316:Potomac Yard:703-305-6135:7509P:RAB1

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Prometryn	Summary of Analytical Chemistry and Residue Data	DP#:  357098
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