UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

																																													OFFICE OF PREVENTION,
PESTICIDES

																																														AND TOXIC SUBSTANCES

MEMORANDUM

	06-November-2008

Subject: 	S-Metolachlor:  Docket ID Number: EPA-HQ-OPP-2007-0445,
Federal Register / Vol. 72, No. 152 / Wednesday, August 08, 2007 /
Proposed Rules, Syngenta comments on Proposed Rule to modify certain
tolerances for the herbicide.

		

PC Code: 108800	DP Barcode:  308245 

Decision No.: 348979	Registration No.:  None

Petition No.: None	Regulatory Action: None

Risk Assessment Type: None	Case No.:  None

TXR No.: None	CAS No.: 87392-12-9

MRID Nos.: None	40 CFR: 180.368 



From:		P. Yvonne Barnes, Chemist

		Reregistration Action Branch II

		Health Effects Division (7509P)

Through:		Felecia A. Fort, Chief

		Reregistration Action Branch II

		Health Effects Division (7509P)

To:		Jane Scott-Smith		

								Special Review and Reregistration Division 

		Registration Division (7505P)

THE ENVIRONMENTAL PROTECTION AGENCY, under 40 CFR Part 180, issued
[EPA–HQ–OPP–2007–0445; FRL–8138–8] on Acephate,
Chlorpyrifos, Fenbutatin-Oxide (Hexakis), Metolachlor, MCPA, Pyrethrins
and Triallate, Proposed Tolerance Actions: Proposed Rule for public
comment in the Federal Register / Vol. 72, No. 152 / Wednesday, August
08, 2007 / Proposed Rules.  Syngenta Incorporated submitted comments. 

Background

DP Barcode: D296904, R. Loranger, 04/17/2006

S-Metolachlor (an isomer enriched form of Metolachlor) is a selective,
chloroacetanilide herbicide that is applied to a variety of crops as a
preplant, preplant-incorporated (PPI), pre-emergence, or post-emergence
application, primarily for the control of grass weeds.  S-Metolachlor is
registered to Syngenta Crop Protection, Incorporated for use on a wide
variety of crops with the intent of replacing the racemic mixture of
metolachlor. Following recommendations made in the revised Tolerance
Reassessment Eligibility Decision (TRED) for Metolachlor and
S-Metolachlor (DP Barcode: D292881, S. Kinard, 08/15/2003), tolerances
for metolachlor and s-metolachlor have been separated. 

  

Based on the adequate metolachlor and S-metolachlor plant and animal
metabolism studies, the nature of S-Metolachlor residues in plants and
animals is understood. For both metolachlor and S-metolachlor the
residues of concern in plants and animals include the parent compound
(having both R and S-enantiomers with an estimated ratio of 12:88 for R:
S) and its metabolites, determined as the derivatives
2-[(2-ethyl-6-methylphenyl) amino]-1-propanol and
4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-methyl-3-morpholinone (DP
Barcode: D226780, L. Kutney, 11/12/1996).  The residue definitions for
S-Metolachlor (parent and metabolites) which are regulated under the
“Pest Control Products Act” are equivalent between the United States
and Canada.

An excerpt highlighting the main issues from the FR notice is provided
for reference below:

ENVIRONMENTAL PROTECTION AGENCY {40 CFR Part 180, [EPA-HQ-OPP-2007-0445;
FRL-8138-8]}:   EPA is proposing to revoke certain tolerances for the
herbicide metolachlor… Also, EPA is proposing to modify certain
tolerances for the herbicide metolachlor… In addition, EPA is
proposing to establish new tolerances for the herbicides metolachlor…
The regulatory actions proposed in this document are in follow-up to the
Agency's reregistration program under the Federal Insecticide,
Fungicide, and Rodenticide Act (FIFRA), and tolerance reassessment
program under the Federal Food, Drug, and Cosmetic Act (FFDCA) section
408(q).  [[Page 44443]] 5. Metolachlor (including S-Metolachlor). The
Agency is also revising the commodity terminology for certain tolerances
to current Agency practice. Therefore, EPA proposes transferring
tolerances from 40 CFR 180.368(a) (1) to a new section designated 40 CFR
180.368 (d) (1) for the combined residues (free and bound) of the
herbicide metolachlor. [[Page 44444]] EPA is revising commodity
terminology to current Agency practice. The current terminology for seed
and pod vegetables (except soybean) crop group is vegetable, legume,
edible podded, subgroup 6A; pea and bean, succulent shelled, subgroup
6B; and pea and bean, dried shelled, except soybean, subgroup 6C.

Syngenta Crop Protection commented on the proposed rule to modify
certain tolerances for the herbicide S-Metolachlor. Syngenta comments on
five maximum residue levels (MRLs) tolerance differences between Canada
and the U.S., referencing Docket ID Number: EPA-HQ-OPP-2007-0445
(Federal Register Notice of 08-Aug-2007 (Volume 72, Number 152)).  Note
that HED’s responses are combined for items #2 and #3 and also for
items #4 and #5 due to their respective similarities. 

Syngenta’s comments (item 1):

Item #1: Revocation of tolerance in stone fruit – Use of S-Metolachlor
in stone fruit is an important tool for Canadian fruit producers and
therefore, it would be beneficial to maintain U.S. tolerances to avoid
any trade irritant issues for these crops being exported from Canada to
the U.S. Canada currently has a tolerance of 0.1 ppm for S-Metolachlor
in apples, apricots, cherries, peaches/nectarines, pears and plums. 

HED responds to Item #1:  There are no reported tolerances for
S-Metolachlor in/on fruit, stone group 12; 40CFR §180.368 (2000 to
present).  However, it is the Agency’s understanding that the
registrant has previously proposed (DP Barcode: D282607, C. Jarvis,
05/23/2002) to revoke tolerances (0.1) in/on fruit, stone group 12 for
Metolachlor and HED  agreed to remove all references to stone fruit from
its disciplinary chapters.  However, HED concurs that there is a
Canadian MRL (0.1 ppm) for S-Metolachlor on apples, apricots, cherries,
peaches/nectarines, pears and plums.   No proposals/petitions have been
submitted to the Agency by the registrant for an S-Metolachlor tolerance
in/on fruit, stone group 12. Therefore, the registrant should submit to
the Agency a proposal/petition for a tolerance on fruit, stone group 12
for S-Metolachlor.

Syngenta’s comments (items 2 and 3):

Item #2:  Increase in tolerance for Crop Group 6A from 0.3 ppm to 0.5
ppm - Canada currently has a tolerance of 0.3 ppm for S-Metolachlor in
peas and snap beans.  An increase in the U.S. tolerance could result in
a trade irritant for these crops exported from the U.S. to Canada. 

Item #3: Decrease in tolerance for Crop Group 6C from 0.3 ppm to 0.1
ppm - Canada currently has a tolerance of 0.3 ppm for S-Metolachlor in
dry beans.  A decrease in the U.S. tolerance could result in a trade
irritant for these crops exported from Canada to the U.S. 

HED’s response to Items #2 and #3: 	The legume vegetable field trial
data (DP Barcode: D350492, D. McNeilly, 10/21/2008) indicate that
combined S-Metolachlor residues in/on beans and peas resulting from the
three types of applications are similar within each crop subgroup and
within the crop group. For the legume vegetable crop subgroups 6A, 6B
and 6C, the maximum observed residues from the trials using the
broadcast foliar application were used to determine recommended
tolerances. These data indicate that a 0.3 ppm tolerance for residues on
crop group 6 is appropriate. HED concludes that Crop Group 6A, 6B and 6C
tolerances/MRLs remain harmonized with Canada at 0.3 ppm for
S-Metolachlor.

 

Syngenta’s comments (items 4 and 5):

Item #4:  Increase in tolerance for egg and meat from 0.02 pm to 0.04
ppm - Canada currently has a tolerance of 0.02 ppm for S-Metolachlor in
eggs, meat of cattle, goats, hogs, poultry and sheep.  An increase in
the U.S. tolerance could result in a trade irritant for these animal
products exported from the U.S. to Canada. 

Item #5: Increase tolerance in animal liver from 0.05 ppm to 0.1 ppm –
Canada currently has a tolerance of 0.05 ppm for S-Metolachlor in liver
of cattle and poultry.  An increase in the U.S. tolerance could result
in a trade irritant for these animal products exported from the U.S. to
Canada. 

HED’s response to Items #4 and #5: As previously stated in the
“Revised Metolachlor and S-Metolachlor Residue Chemistry Chapter for
the Tolerance Reassessment Eligibility Decision (TRED)”, (DP Barcode:
D292881, S. Kinard, 08/15/2003).  In the available ruminant feeding
study, dairy cows were administered metolachlor at a level equivalent to
60 ppm in the feed for up to 28 consecutive days. Animals were dosed:
(1) by mixing the compound in the feed; (2) orally via gelatin capsules;
and (3) by intra-rumen injections. Milk samples for residue analysis
were collected on days 0, 1, 4, 7, 12, 14, 21, and 28, and cows were
sacrificed at 14, 21, and 28 days. There were no detectable residues of
CGA-37913 (<0.006 ppm) or CGA-49751 (<0.01 ppm) in any of the milk
samples, and there were no detectable residues of CGA-37913 (<0.02 ppm)
and CGA-49751 (<0.02 ppm) in any tissues except liver or kidney. If
residues in beef muscle are corrected for decline of CGA-37913 residues
during storage, the maximum combined residues in beef muscle would be
<0.06 ppm. At each sampling interval, residues in liver were comprised
of CGA-37913 at 0.11 ppm and CGA-49751 at 0.02 ppm, for combined
residues of 0.13 ppm. 

Based upon a maximum reasonable balanced dietary burden (MRDB) of 11.4
ppm for cattle, the 60 ppm dose level in the ruminant feeding study is
equivalent to 5.3x the MRDB for cattle. Extrapolating the residue data
from the ruminant study to a 1x feeding level for cattle, the maximum
combined residues would be 0.01 ppm in fat, 0.01 ppm in meat and 0.03
ppm in liver. As these residue levels are below the method LOQ in fat
and meat, the MRLs/tolerances for these residues should remain at 0.02
ppm and are harmonized with Canada.  HED acknowledges the importance of
harmonizing MRLs/tolerances of S-Metolachlor with Canada in/on the liver
of cattle and will increase that tolerance to 0.05 ppm.

As previously stated in the “Revised Metolachlor and S-Metolachlor
Residue Chemistry Chapter for the Tolerance Reassessment Eligibility
Decision (TRED)”, (DP Barcode: D292881, S. Kinard, 08/15/2003), in the
available poultry feeding study, laying hens were fed metolachlor at
levels of 0, 0.1, 0.5, and 2.0 ppm in the diet. These feeding levels are
equivalent to 0.2x, 0.98x, and 3.9x the MRBD for poultry. Eggs samples
were taken on days 1, 3, 7, 10, 14, and 21, and birds were sacrificed
after 7, 14, 21, and 28 days for tissue analysis. Only tissues from the
two highest feeding levels (0.5 and 2.0 ppm) were analyzed. No
detectable residues were found in egg whites or egg yolks (<0.02 ppm for
CGA-37913), and no detectable residues of CGA-37913 (<0.02 ppm) were
found in any poultry tissues, meat or fat, except liver CGA-37913 (<0.02
to 0.03 ppm) and CGA-49751 (<0.05 ppm). 

Based on the LOQ (0.02 ppm) for eggs and meat and the LOQ (0.05 ppm) for
liver of the tolerance enforcement method; HED concludes that the
MRL/tolerance for S-Metolachlor in/on egg and the meat of cattle, goats,
hogs, poultry and sheep, should remain harmonized with Canada at 0.02
ppm and the MRL/tolerance for S-Metolachlor in/on the liver of poultry
should remain harmonized with Canada at 0.05 ppm.  

Table 1.	Calculation of Dietary Burdens of S-Metolachlor Residues to
Livestock (June 2008).

Feedstuff	Type1	% Dry Matter2	% Diet2	Tolerance (ppm)	Dietary
Contribution (ppm)3

Dairy Cattle

Sorghum grain	CC	86	40	0.3	0.1

Sunflower	PC	92	10	1.0	0.1

Sugar Beets Dried/Molasses 	 CC	75	5	2.0	0.1

Grasses Forage/Silage	RR	25	20	10.0	8.0

Corn Field, Silage	R	40	15		8.0	3.0

Cowpea	R	30	10	15.0	5.0

TOTAL BURDEN	100	11.4

1	R - Roughage; CC - Carbohydrate concentrate; PC - Protein
concentrates.  2	OPPTS 860.1000 Table 1 Feedstuff (June 2008). 3
Contribution = ([tolerance /% DM] X % diet) for beef and dairy cattle 

References

Author	DP Barcode/ MRID	Date	Title

Loranger, R	D296904	04/17/2006	S-Metolachlor. Petition for Tolerances on
Various Crops, Crop Groups, and Livestock Commodities. Summary of
Analytical Chemistry and Residue Data.

Kinard, S.	D292881	08/15/2003	PP#s: 7F04897, 9E06055, 7E04916, 2E06374,
4E04420, 8E05029, and 8E05030. Revised Metolachlor and S-Metolachlor
Residue Chemistry Chapter for the Tolerance Reassessment Eligibility
Decision (TRED) and Registration for Use on Asparagus, Carrots, Cotton,
Horseradish, Green Onions, Peppers, Rhubarb, Sugar Beet, Sunflower, and
Swiss Chard; DP Barcode D292881; Rereg. Case 0001. DP Barcodes: D255484,
D258813, D258816, D258825, D258958, D259117, D280858, D288570. Case
Nos.: 285998, 289117, 289218, 290491, 290492, 292279, 294578. PC Codes:
108800 and 108801. Submissions: S560957, S630066, S566987, S566988,
S566992, S566995, S567580. 40 CFR 180. 368. MRID Nos.: 44378401,
44908701, 45544701. (August 15, 2003)

Office of the Federal Register	None	2000 to 2008	40CFR§180.368 
(Metolachlor and S-Metolachlor)

HED ChemSAC	None	June 2008	Revisions of Feedstuffs in Table 1 of OPPTS
Test Guideline 860.1000 and Guidance on Constructing Maximum Reasonably
Balanced Diets (MRBD)

McNeilly, D	D350492	10/21/2008	S-Metolachlor.  Amended Use Directions
for Sorghum and Soybeans; Revisions to Rotational Crop Restrictions;
Registrant’s Responses to Deficiencies Noted in the Revised
S-Metolachlor TRED.  Summary of Analytical Chemistry and Residue Data.

Ciba-Geigy Corp.	MRID# 00106041	07/07/1982	 (1982) Metolachlor--Peanuts:
Lay by Applications: Split Applications (Including at Cracking Mixtures
with Naptalam/Dinoseb) at Cracking Applications with Dinoseb.
(Compilation; unpublished study received under 100-597; CDL:070977-A)

Ciba-Geigy Corp.	MRID# 00015413	07/11/1975	Mattson, A.M. (1975)
CGA-24705 Residues in Milk, Meat, Eggs and Chickens (Three Level Feeding
Studies): Report No. GAAC-75059. (Unpublished study received Jan 19,
1977 under 100-583; submitted by Ciba-Geigy Corp., Greensboro, N.C.;
CDL:095747-X)



S-Metolachlor	     	DP Barcode: D308245

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