              OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
              OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
                                       
                                       
                                       
                                       
                                       
                                       
                               December 7, 2017

                                                                PC Code: 129034
MEMORANDUM	DP Barcodes: 441023

SUBJECT:	Flumioxazin: Drinking Water Assessment for a Section 3 New Use for Flumioxazin (EPA Reg. No. 59639-193, -206, -207, -97) Applications to Grass Grown for Seed 
FROM:	Larry Liu, Ph.D., Chemist    
      Environmental Risk Branch 5
			Environmental Fate and Effects Division (7507P)		

THRU: 	Elyssa Arnold, Acting Branch Chief
      Environmental Risk Branch 5
      Environmental Fate and Effects Division (7507P)	

TO:		Donna Davis, Branch Chief
		Monica Hawkins, Risk Assessor
      Risk Assessment Branch 6
      Health and Effects Division (7509P)

      Sidney Jackson, Risk Manager Reviewer
		Rosanna Louie-Juzwiak, Acting Branch Chief
			Minor Use and Emergency Response Branch
			Registration Division (7505P)


The Interregional Research Project No. 4 (IR-4) has proposed Section 3 new uses for the herbicide flumioxazin (2-[7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1, 4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione) on grass grown for seed in Washington, Oregon and Idaho. The submission includes the product labels for Flumioxazin Technical Herbicide, (EPA Reg. No. 59639-97), Fierce(R) M.U.P., (EPA Reg. No. 59639-206), Valor(R) M.U.P., EPA (Reg. No. 59639-207), and the end use product V-10233 Herbicide (EPA Reg. No. 59639-193). The proposed new use and the corresponding maximum application rates are shown in Table 1.  



Table 1.  Application Information for Proposed New Uses of Flumioxazin.
Chemical (labels)
Proposed new use
Single application rate (lb ai/A)
Maximum application frequency
Maximum yearly application rate (lb ai/A/year)
Application interval (days)
Application methods
V-10233 Herbicide, EPA Reg. No. 59639-193
Grass grown for seed
0.03-0.06
1
0.06
N/A
ground
aerial 


Since the currently proposed single and yearly application rates are lower than those used in the previous assessments, the drinking water assessment for flumioxazin completed on 7/21/10 can be used in place of a new assessment for the currently proposed new use (see results in Table 2). These EDWCs were used by HED in the most recent dietary exposure and risk assessment for flumioxazin.

Table 2.  EDWCs recommended in the DWA completed on 7/21/10.

Compound

Acute EDWCs

Chronic EDWCs (Non-Cancer)
Chronic EDWCs (Cancer)
Flumioxazin
400 ppb
9.4 ppb
13.1 ppb
482-HA
-
21.6 ppb
21.6 ppb
APF
-
110.1 ppb
110.1 ppb
THPA
-
88.9 ppb
88.9 ppb

