Document ID: EPA-HQ-OPP-2010-0938-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-05-11T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460      

                                       
                                                      OFFICE OF CHEMICAL SAFETY
                                                       AND POLLUTION PREVENTION

MEMORANDUM

Date:		24-March-2011

Subject:	Glyphosate.  Section 3 Registration for Application of the Potassium Salt of Glyphosate to Roundup Ready[(R)] Field Corn.  Human-Health Risk Assessment.  

PC Codes:  103613 and 417300
DP Barcode:  D381826
Decision No.:  437140
Registration Nos.:  524-537; 524-549
Petition No.:  0F7741
Regulatory Action:  Section 3
Risk Assessment Type:  aggregate
Case No.:  178
TXR No.:  not applicable
CAS No.:  70901-20-1
MRID No.:  not applicable
40 CFR:  180.364 

From:	Tom Bloem, Chemist
	Risk Assessment Branch 1; Health Effects Division (RAB1/HED; 7509P)\

Through:	Dana M. Vogel, Branch Chief
		George F. Kramer, Ph.D., Senior Chemist
		RABI/HED (7509P)

To:	James Tompkins/Hope Johnson RM 25
	Registration Division (RD; 7505P)

Glyphosate (N-(phosphonomethyl) glycine) is a nonselective Group 9 herbicide that is currently registered for pre- and post-emergence application to a variety of fruit, vegetable, and field crops.  Tolerances are currently established for residues of glyphosate in/on various plant commodities at 0.2-400 ppm (40 CFR §180.364(a)) and for the combined residues of glyphosate and N-acetyl-glyphosate (expressed as glyphosate) in/on field corn, soybean, aspirated grain fractions, and livestock commodities at 0.1-310 ppm.  The Glyphosate Reregistration Eligibility Decision document was issued September 1993.  

Monsanto indicated that they have developed a new variety of genetically-altered field corn (MON 87427 and MON87441) which enables properly timed glyphosate applications to provide tassel control.  Monsanto indicated that tassel control is desired as this will allow the generation of specific cross pollinations without the use of traditional methods to control self pollination.  This new variety of field corn is to be used only in seed corn production (Monsanto termed the process Round Hybridization System[(TM)] (RHS[(TM)])) and involves slightly later glyphosate application than that currently registered for field corn (same seasonal application rate; see Attachment 1 for proposed application scenario).  

The petitioner has submitted adequate magnitude of the residue data which indicates that the currently established field corn forage and grain tolerances, as well as the currently established livestock tolerances, are adequate to cover the proposed new use.  However, the field corn forage tolerance, for the combined residues of glyphosate and N-acetyl-glyphosate (expressed as glyphosate), should be increased to 13 ppm (D383931, T. Bloem, 16-Mar-2011).  

HED recently completed a human-health risk assessment associated with the application of glyphosate to glyphosate-tolerant sweet corn (D372052, T. Bloem et al., 31-Aug-2010).  This assessment yielded an aggregate exposure to glyphosate which did not exceed HED's level of concern.  HED concludes that a revised human-health risk assessment is unnecessary to support the current-proposed uses for the following reasons:

●No new toxicological data were submitted since the previous risk assessment (see D372052 (T. Bloem et al., 31-Aug-2010) for a summary of the toxicological data).
●The previous dietary exposure analysis assumed tolerance-level residues and 100% crop treated and the current action result in an increase in only the field corn forage tolerance (livestock feed item). 
●Since no new toxicological data were submitted and a revised dietary exposure analysis is unnecessary, the previous conclusions concerning the Food Quality Protection Act (FQPA) Safety Factor remain valid.  
●The proposed new field corn application scenario does not necessitate a revised occupational exposure assessment (assessment conducted as part of the currently registered field corn application scenario remains valid).  

Recommendation:  Provided the petitioner submits revised Sections B and F (see below), HED concludes that the toxicological, residue chemistry, and occupational/residential exposure databases support a conditional registration for the proposed application of glyphosate to field corn.  An unconditional registration may be established upon submission of data which adequately addresses the toxicological deficiencies specified below.

Summary of Deficiencies:

Acute and subchronic neurotoxicity studies.
Immunotoxicity study.
●Section B:  HED requests that the supplemental labels be altered to indicate the following:  (1) the minimum spray volume for ground and aerial application is >2 gallons per acre (GPA); (2) postemergent directions should indicate that they apply to field corn up to the V8 crop stage and that a maximum of 2.3 lb ae/acre/season may be applied; and (3) preharvest interval (PHI) of 30 days for forage and 7 days for grain and stover.
●Section F:  HED requests that a revised Section F be submitted proposing a 13-ppm field corn forage tolerance for the combined residues of glyphosate and N-acetyl-glyphosate (expressed as glyphosate).   

Attachment 1:  Proposed Application Scenarios and Requested Changes to the Proposed Labels

T. Bloem:S10945:Potomac Yard 1:703-605-0217:7509P:RAB1
Attachment 1:  Proposed Application Scenarios and Requested Changes to the Proposed Labels.

The petitioner submitted proposed supplemental labels for Roundup WeatherMAX[(R)] (EPA Reg. No. 524-537) and Roundup Power MAX[(R)] (Reg. No. 524-549); both of these products are soluble-concentrate (SC) formulations consisting of glyphosate as the potassium salt at 4.51 lb ae/gallon.  The submitted supplemental labels indicate that the application scenarios are for use in research field trials and for seed production of corn hybrids using the RHS[(TM)] system.  Table 1 is a summary of the proposed application scenarios.  The proposed use directions are similar to that currently registered with the exception of the tassel control instructions (V8-V13); maximum seasonal application rate is the same.  HED requests that the supplemental labels be altered to indicate the following (a revised Section B is requested):  (1) the minimum spray volume for ground and aerial application is >2 GPA; (2) postemergent directions should indicate that they apply to field corn up to the V8 crop stage and that a maximum of 2.3 lb ae/acre/season may be applied; and (3) PHI of 30 days for forage and 7 days for grain and stover.

Table 1:  Summary of Proposed Roundup Ready[(R)] Field Corn Application Scenario.
                                  Formulation
                                (EPA Reg. No.)
                                 App. Timing 
                                   App. Rate
                                 (lb ae/acre)
                          Max. App. Rate (lb ae/acre)
                        Use Directions and Limitations
Roundup WeatherMAX[(R)] (EPA Reg. No. 524-537; SC; 4.51 lb ae/gal)

Roundup Power MAX[(R)] (EPA Reg. No. 524-549; SC; 4.51 lb ae/gal)
preplant, at planting, preemergence
                                 not specified
                                     3.72
-For use in research field trails and for seed production of corn hybrids using RHS[(TM)].  
-Allow a minimum of 10 days between postemergent applications.

postemergence
                                   0.56-0.78
                                 not specified

tassel control (V8-V13 or 100 growing degree units; before flowering)
                                   0.39-1.13
                                     2.26

preharvest
                                     0.78
                                 not specified

postharvest
                                 not specified
                                 not specified

maximum seasonal application rate
                                      --
                                     5.98