       

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY   

           WASHINGTON, D.C. 20460

	

						FEB 24 2006

OFFICE OF PREVENTION,                                              
PESTICIDES AND TOXIC                                                    
                   SUBSTANCES 

      

MEMORANDUM

SUBJECT:	Review of Application to Extend/Amend the Experimental Use
Permit (EPA 

		Reg. No. 67979-EUP-4) and existing temporary exemption from the
requirement 

		of tolerance [40 CFR Part 174.456] for Modified Cry3A (mCry3A)
Bacillus 

		thuringiensis insect control protein as expressed in Event MIR604 corn
plants 

		and Breeding stack of Event MIR604 corn with Event Bt11 Corn
expressing a 

		Cry1Ab Bt insect control protein (MIR604 x Bt11), submitted by
Syngenta 

		Seeds, Inc. – Field Crops- NAFTA.

TO:		Mike Mendelsohn, Regulatory Action Leader

		Microbial Pesticides Branch, Biopesticides and

		Pollution Prevention Division (7511C)

FROM:	Annabel Fellman, Environmental Protection Specialist		[signed]				

		Microbial Pesticides Branch, Biopesticides and		

		Pollution Prevention Division (7511C)

THROUGH:	John L. Kough, Ph.D., Biologist					[signed]

		Microbial Pesticides Branch, Biopesticides and			

		Pollution Prevention Division (7511C)

ACTION REQUESTED: To review Syngenta Seeds, Inc.’s application to
extend and amend the Experimental Use permit (EPA Reg. No. 67979-EUP-4)
and existing temporary exemption from the requirement of tolerance [40
CFR Part 174.456] for mCry3A Bt insect control protein as expressed in
Event MIR604 corn plants and Breeding stack of Event MIR604 corn with
Event Bt11 Corn expressing a Cry1Ab Bt insect control protein (MIR604 x
Bt11).

CONCLUSION:    In previously reviewed studies, the product
characterization, protein expression, toxicological and allergenicity
data support the finding that there is a reasonable certainty of no harm
to humans from the aggregate exposure to the residues of the mCry3A
protein, including all anticipated dietary exposures and all other
exposures for which there is reliable information.  These data support
the extension and amendment of the EUP for the period of March 2006
through February 28, 2007 as well as extending the expiration date for
the current temporary exemption from the requirement of tolerance for
mCry3A until October 17, 2007.

*THIS REVIEW DOES NOT CONTAIN CONFIDENTIAL BUSINESS INFORMATION*

DATA REVIEW RECORD:

Active Ingredient:		Modified Cry3A (mCry3A) Bacillus thuringiensis
insecticidal protein and the genetic material necessary for their
production (via pZM26) in transgenic maize (corn) plants derived from
transformation Event MIR604 and Breeding stack of Event MIR604 corn with
Event Bt11 Corn expressing a Cry1Ab Bt insect control protein (MIR604 x
Bt11).

Product Name:			Event MIR604 Maize Plants Expressing Modified Cry3A
Bacillus thuringiensis Protein 

Company Name:			Syngenta Seeds, Inc. – Field Corps- NAFTA

ID No:				67979

Chemical Number:	 	006509

Decision Number:		360263

DP Barcode:			324829						

MRID No:			

Not Assigned			Administrative Materials:  Application to Extend/Amend 

				Experimental Use Permit [EPA Reg. No. 97979-EUP-4] and Petition 

				for Extension of the Temporary Exemption from the Requirement of 

				Tolerance for mCry3A Bt insect control protein.

BACKGROUND:

Syngenta Seeds Inc. synthetically modified a cry3A gene from Bacillus
thuringiensis subsp. tenebrionis to optimize the gene for expression in
maize (corn) and to enhance its activity against the western corn
rootworm (WCRM; Diabrotica virgifera vigifera) and northern corn
rootworm (NCRM; D. longicornis barberi).  Syngenta’s maize Event
MIR604 corn plants were a result of a corn plant transformation with the
synthetic modified cry3A gene, which provides resistance to these pests.
 Transformation was conducted using immature maize embryos derived from
a proprietary Zea mays line, via Agrobacterium-mediated transformation. 


Event MIR604 maize also contains the pmi gene, which was introduced
along with the mCry3A protein via the same pZM26 transformation vector. 
The gene represents the manA gene from Escherichia coli and encodes the
enzyme phosphomannose isomerase (PMI), which was employed as a
selectable marker during the process of regenerating plant material
following transformation.  An existing permanent exemption from the
requirement of a tolerance has been established for PMI in all crops
when used as a plant-incorporated protectant inert ingredient (see 40
CFR 180.1252, effective May 14, 2004).  

EPA issued an experimental permit for the use Bt mCry3A protein and the
genetic material necessary for their production (via plasmid pZM26) in
Event MIR604 corn and associated activities (such as collection of field
data; harvesting & processing of seed after last planting) on 575 acres
of field corn.  In the Federal Register of  April 6, 2005 (70 FR 17323),
the Agency also established a temporary exemption from the requirement
of a tolerance for Modified Cry3A and the genetic material necessary for
their production in corn, which will expire October 15, 2006.  To
support their requests for EUP and a temporary tolerance exemption,
Syngenta Seeds, Inc. submitted product characterization and protein
expression analyses, toxicological and allergenicity data [see memoranda
from A. Fellman through J. Kough to M. Mendelsohn, dated 02/11/2005,
02/23/2005, 03/03/2005, and 05/31/2005].  

On April 30, 2004, Syngenta Seeds, Inc. submitted an application for
FIFRA Sec. 3 Registration of the mCry3A PIP in MIR604 corn (EPA Reg. No.
67979-L).  The final study to complete remaining data requirements for
Sec. 3 registration for Event MIR604 corn was reviewed and is pending
upon Agency approval [see memorandum from A. Fellman through J. Kough to
M. Mendelsohn, dated 02/15/2006].  

In this report, Syngenta Seeds, Inc. is seeking an extension and
amendment of its current  EUP [EPA Reg. No. 67979-EUP-4] to allow:  1)
continued field testing of the mCry3A Bt insect control protein and the
genetic material necessary for its production in Event MIR604-derived
field corn plants, and 2) the first large-scale field testing of a
conventional breeding ‘stack’ of Event MIR604 corn with Event Bt11
corn expressing a Cry1Ab Bt insect control protein (MIR604 x Bt11 corn).
 MIR604 plants are currently being field tested, which was approved
Marcy 23, 2005 and allows plantings through February 28, 2006.  The
Cry1Ab PIP in Bt11 field corn has been registered since 1996 under EPA
Reg. No. 67979-1.  By combining the MIR604 and Bt11 via conventional
breeding, corn hybrids produce both the mCry3A protein for control of
key coleopteran pests and Cry1Ab protein for control of key lepidopteran
pests.  Syngenta is requesting authorization for plantings beginning in
mid-March 2006 and continuing through February 2007, with associated
field activities (i.e. data collection, harvesting and processing of
seed) continuing through October 15, 2007.  The purpose of this report
is to confirm that the previously submitted data can support the
extension and amendment to the EUP and there are no new data
requirements or concerns.

Extension of Temporary Exemption from the Requirement of a Tolerance
(4F6838)

EPA has established an exemption from tolerance requirements pursuant to
FFDCA section 408(j)(3) for Bacillus thuringiensis Cry3A delta-endotoxin
and the genetic material necessary for its production in potatoes, and
this tolerance exemption has been reassessed and meets the 408(c)(2)
standard (see 40 CFR 180.1147).  An exemption from the requirement of a
tolerance has been established for PMI in all crops when used as a
plant-incorporated protectant inert ingredient (see 40 CFR 180.1252,
effective May 14, 2004).   

For the combination of MIR604 and Bt11 traits in the conventionally bred
MIR604 x Bt11 plants, an exemption from the requirement of a tolerance
has been established for Bt Cry1Ab delta-endotoxin and the genetic
material necessary for its production in all crops (see 40 CFR
180.1173).  Moreover, the marker protein in Bt11 corn, phosphinothricin
acetyltransferase (PAT), is also exempt from the requirement of a
tolerance (see 40 CFR 180.1151). 

Concurrently with the issuance of the EUP permit, in the Federal
Register of  April 6, 2005 (70 FR 17323), the Agency established a
temporary exemption from the requirement of a tolerance for Modified
Cry3A and the genetic material necessary for their production in corn
which will expire October 15, 2006.  Syngenta Seeds, Inc. also submitted
a petition for a permanent exemption from the requirement of a tolerance
pursuant to section 408(d)(1) of the FFDCA for the PIP mCry3A Bt insect
control protein and the genetic material necessary for its production in
all corn (Petition File Symbol PP 4F6838).  This petition was reviewed
and is also pending upon Agency approval [see memorandum from A. Fellman
through J. Kough to M. Mendelsohn, dated 02/15/2006].  

In this report, the present EUP amendment/extension application is
accompanied by a petition to extend the expiration date on the current
mCry3A temporary tolerance exemption by one year, October 17, 2007.

DATA SUMMARY:

Previously submitted studies demonstrate the lack of toxicity of the
mCry3A protein following acute oral high-dose exposure to mice, the lack
of post-translational glycosylation, rapid degradation of mCry3A upon
exposure to simulated mammalian gastric fluid, and the lack of
significant amino acid sequence homology of the mCry3A protein to
proteins known to be mammalian toxins or human allergens. Moreover,
little to no human dietary exposure to mCry3A protein is expected to
occur via transformed corn.  Collectively, these data allowed the Agency
to make a determination that for human health, there is a reasonable
certainty that no harm will result from aggregate exposure to the U.S.
population to mCry3A protein and the genetic material necessary for its
production [as stated in the memoranda from A. Fellman, through J.
Kough, Ph.D., to M. Mendelsohn, dated May 31, 2005 and Feb. 15, 2006].
It was concluded that there are no adverse effects on human health from
the proposed use of mCry3A protein expressed in corn and the Agency
still supports this contention.  The same rationale supporting the
permanent tolerance determination would justify extending the temporary
tolerance until October 17, 2007 since the limited acreage would further
limit potential dietary exposure. 

Upon review of the application to extend/amend the EUP for mCry3A, the
product chemistry and toxicology data were referenced to previously
submitted data. These data have been reviewed and found acceptable by
the Agency  [see memoranda from A. Fellman through J. Kough to M.
Mendelsohn, dated 02/11/2005, 02/23/2005, 03/03/2005, 05/31/2005, and
02/16/2006].  Furthermore, the petition for the extension of the
temporary tolerance exemption does not contain any new data and the
safety conclusions are the same as previously determined by the Agency
[see memorandum from A. Fellman through J. Kough to M. Mendelsohn, dated
02/16/2006].

CONCLUSION:

In previously reviewed studies, the product characterization, protein
expression, toxicological and allergenicity data support the finding
that there is a reasonable certainty of no harm to humans from the
aggregate exposure to the residues of the mCry3A protein, including all
anticipated dietary exposures and all other exposures for which there is
reliable information, given the limited duration and acreage involved in
this EUP.  There were no additional data neither submitted by Syngenta
Seeds, Inc. nor requested by the Agency in conjunction with this request
for an extension and amendment for the EUP (EPA Reg. No. 67979-EUP-4)
and temporary tolerance exemption (40 CFR 174.456).  Therefore, these
data support the extension and amendment of the EUP for the period of
March 2006 through February 28, 2007 as well as extending the expiration
date for the current temporary exemption from the requirement of
tolerance for mCry3A until October 17, 2007.

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