              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







                                August 30, 2017
MEMORANDUM

SUBJECT:	Etoxazole: Estimated Drinking Waters Concentrations for Etoxazole, and Its Transformation Products R-8 and R-13, for the Use in the Human Health Risk Assessment: New Uses on Sweet Corn and Various Crop Group Conversions
		(PC Code 107091; DP Barcode 440694)

FROM:	José Meléndez, Chemist
		Environmental Risk Branch 5
		Environmental Fate and Effects Division (7507P)

THRU:	Mah T. Shamim, Ph.D., Branch Chief
            Environmental Risk Branch 5
		Environmental Fate and Effects Division (7507P)

TO:		Marianne Lewis, Risk Manager Reviewer
      Venus Eagle, Product Manager #1
		Meredith Laws, Branch Chief
		Invertebrate-Vertebrate Branch 3

		Sidney Jackson, Risk Manager Reviewer
      Dan Rosenblatt, Acting Branch Chief
		Minor Use and Emergency Response Branch
		Registration Division (7505P)

AND:		Jennifer R. Tyler, Risk Assessor
      Christine Olinger, Acting Branch Chief
		Registration Action Branch 1
		Health Effects Division (7509P)

This memo presents the Environmental Fate and Effects Division (EFED) Tier I Estimated Surface and Ground Drinking Water Concentrations (EDWCs) for etoxazole and its transformation products R-8 and R-13, calculated using the Tier I surface water model FIRST and the Tier I/II groundwater model PRZM-GW (in the tier I mode), for use in the human health risk assessment.  The registrant, Valent U.S.A. Corporation, submitted a petition to use the chemical on sweet corn in the end-use products Zeal[(R)] WP Miticide (EPA Reg. No. 59639-138) and Zeal[(R)] SC Miticide (EPA Reg. No. 59639-202).  Various crop group conversions were also petitioned.  

Based on an inspection of the uses of etoxazole, it was found that the previously modeled crop `mint' represents the scenario with the highest exposure and consequently the highest surface water EDWCs (with a maximum single application rate of 0.18 lb a.i./A/application x two applications/season or 0.36 lb a.i./A/season).  Additionally, in a previous Drinking Water Assessment (DWA), groundwater EDWCs were calculated for the currently approved highest rate of 0.135 lb a.i./A x 2 applications for the use on corn.  Therefore, the EDWCs do not change from the previous ones presented in a previous DWA dated March 31, 2015 (DP Barcode 426353).

The Tier I EDWCs for etoxazole and for its major transformation products R-8 and R-13 [which were modeled as per the request of the Metabolism Assessment Review Committee (MARC) in 2003; DP Barcode 288817, dated 04/23/2003], calculated using FIRST (surface water) and PRZM-GW (groundwater) for use in the human health risk assessment were as shown in Table 1.  A more definitive assessment could be performed, using the Tier II aquatic model PWC and through possible additional refinements.  Should any questions arise, please, contact EFED.

Table 1.  Tier I Estimated Drinking Water Concentrations (EDWCs) for human health drinking water risk assessment application of etoxazole, based on a seasonal application on mint at 0.36 lb a.i./A/season[1] (surface waters) or corn at 0.27 lb a.i./A/season (groundwater)
Chemical[2]
                           Acute EDWC Surface Water
                                FIRST (ppb)[3]
                                 Chronic EDWC
                                 Surface Water
                                FIRST (ppb)[3]
                          Max. Acute EDWC Groundwater
                               PRZM-GW (ppb)[4]
                Max. Chronic EDWC Groundwater  PRZM-GW (ppb)[4]
Etoxazole
                                     6.07
                                     0.618
                                   <0.01
                                   <0.01
R-8
                                     8.03
                                     4.08
                                       
                                       
R-13
                                     1.63
                                     0.063
                                       
                                       
[1] For the use on mint (surface water), the current maximum seasonal rate is lower at 0.18 lb a.i./A x 1 application.  Presented results are from a previous DWA in which two applications/season were assessed instead (DP Barcode 352617, dated February 10, 2009).
[2] For structures of these chemicals, see Table 3.
[3] Results presented in ppb of each of the chemicals, as opposed to ppb of parent equivalent.
[4] Groundwater results are for the total toxic residues (parent + R-8 + R-13), expressed in ppb parent equivalent.  For all six standard scenarios, breakthrough was incomplete even after 100-year modeling; therefore, groundwater EDWCs are low compared to surface water EDWCs.


Use Information

There are three products involved in this petition: Etoxazole Technical (EPA Reg. No. 59639-107) and the end-use products Zeal[(R)] WP Miticide (EPA Reg. No. 59639-138, containing 72% A.I.) and Zeal[(R)] SC Miticide (EPA Reg. No. 59639-202, containing 31.7% A.I. or 2.88 lb A.I./gallon).  The proposed new use on sweet corn is for control of species like banks grass mite, Carmine spider mite, Pacific spider mite, spider mites, strawberry spider mite, two-spotted spider mite.  A single application is proposed at a rate ranging from 0.045 to 0.135 lb a.i./A (only one application is allowed per season on sweet corn), applied by ground or aerial methods (except for New York, where aerial applications are not allowed; Table 2).  The current highest exposure scenario is corn, with two applications at 0.135 lb a.i./A and an interval between applications of 14 days.  Groundwater EDWCs were modeled at the corn rate.  However, previous surface water EDWCs were conducted at 0.18 lb a.i./A/application x 2 applications or 0.36 lb a.i./A/season for the use on mint.  Note that the currently approved rate on mint is 0.18 lb a.i./A x one application/ season, although two applications are allowed per year in one of the labels.

Table 2.  Summary use information for the proposed new uses of etoxazole, based on Zeal[(R)] WP Miticide and Zeal[(R)] SC Miticide labels (New crops and/or crop group changes are redlined.)
                                      USE
                               Single App. Rate
                                 (lb. a.i./A)
                       Max. Number of Apps. at Max. Rate
                              Seasonal App. Rate
                                  (lb a.i./A)
                       Min Interval Between Apps (days)
                                  App Method
                                  PHI (days)
Subgroup 8-10B: Pepper/Eggplant: African eggplant, eggplant, pea eggplant, pepino, roselle, scarlet eggplant, bell pepper, martynia, non-bell pepper, okra, cultivars, varieties and/or hybrids of these
                                  0.09-0.135
                                       1
                              0.135; 0.27/year[3]
                                Not applicable
                                    Ground
                                       7
Crop Group 9: Cucurbit Vegetables: Acorn Squash, Balsam Apple, Balsam Pear, Bittermelon, Butternut Squash, Calabaza Squash, Cantaloupe, Chayote (fruit), Chinese, Cucumber, Chinese Okra, Chinese Waxgourd (Chinese Preserving Melon), Citron Melon, Cucumber, Cucuzza, Gherkin, Edible Gourd, Hechima, Hubbard Squash, Hyotan, Momordica spp., Muskmelon, Pumpkin, Spaghetti Squash, Summer Squash, Watermelon, Winter Squash
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground, aerial[1]
                                       7
Crop Group 11-10: Pome Fruit: Apple; azarole; crabapple; loquat; mayhaw; medlar; pear; Asian pear; quince; Chinese quince; Japanese quince; tejocote; cultivars, varieties, and/or hybrids of these.
                                  0.09-0.135
                                       1
                              0.135; 0.27/year[3]
                                Not applicable
                               Ground (airblast)
                                      14
Crop Group 12-12: Stone Fruit: Apricot; Japanese apricot; capulin; black cherry; Nanking cherry; sweet cherry; tart cherry; Chinese Jujube; nectarine; peach; plum; American plum; beach plum; Canada plum; cherry plum; Chickasaw plum; Damson plum; Japanese plum; Klamath plum; prune plum; plumcot; sloe; cultivars, varieties, and/or hybrids of these.
                                  0.09-0.135
                                       1
                              0.135; 0.27/year[3]
                                Not applicable
                                    Ground
                                       7
Crop Subgroup 13-07A: Caneberry: Blackberry; loganberry; raspberry, black and red; wild raspberry; cultivars, varieties, and/or hybrids of these
                                  0.09-0.135
                                       1
                                     0.135
                                      N/A
                                    Ground 
                                       0
Crop Subgroup 13-07F: Small Fruit Vine Climbing, except Fuzzy Kiwifruit: Amur river grape; gooseberry; grape; hardy kiwifruit; maypop; schisandra berry; cultivars, varieties, and/or hybrids of these
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                                    Ground
                                      14
Crop Subgroup 13-07G: Low Growing Berry: Bearberry; bilberry; blueberry, lowbush; cloudberry; cranberry; lingonberry; muntries; partridgeberry; strawberry; cultivars, varieties, and/or hybrids of these
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                                    Ground
                                       1
Crop Group No. 14-12: Tree Nuts: African nut-tree; almond; beechnut; Brazil nut; Brazilian pine; bunya; bur oak; butternut; Cajou nut; candlenut; cashew; chestnut; chinquapin; coconut; coquito nut; dika nut; ginkgo; Guiana chestnut; hazelnut (filbert); heartnut; hickory nut; Japanese horse-chestnut; macadamia nut; mongongo nut; monkey-pot; monkey puzzle nut; Okari nut; Pachira nut; peach palm nut; pecan; pequi; Pili nut; pine nut; pistachio; Sapucaia nut; tropical almond; black walnut; English walnut; yellowhorn; cultivars, varieties, and/or hybrids of these.
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground (airblast)
                                      28
Crop Group: Tropical and Sub-tropical Fruits (inedible peel): Avocado, papaya, star apple, black sapote, mango, sapodilla, canistel, mamey sapote
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground, Aerial[1]
                                       1
Corn: Field Corn, Popcorn, Corn (grown for seed production)
                                  0.045-0.135
                                       2
                                     0.27
                                      14
                               Ground, Aerial[1]
                                      21
Sweet Corn
                                  0.045-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground, Aerial[1]
                                      21
Subgroup 20C: Cottonseed: Cottonseed; cultivars, varieties, and/or hybrids of these.
                                  0.03-0.045
                                       1
                                     0.045
                                Not applicable
                                Ground, Aerial
                                      28
Hops
                                  0.135-0.18
                                       1
                                     0.18
                                Not applicable
                                    Ground
                                       7
Mint: Peppermint, Spearmint
                                   0.09-0.18
                                       1
                              0.18; 0.36/year[3]
                                Not applicable
                               Ground, Aerial[1]
                                       7
Soybean
                                  0.045-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground, aerial[1]
                                     NS[2]
Non-bearing fruit trees
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                               Ground (airblast)
                                    1 year
Christmas trees
                                  0.09-0.135
                                       1
                                     0.135
                                Not applicable
                                Ground, Aerial
                                      N/A
[1] Not approved for aerial applications in New York.
[2] NS = not specified.  Do not apply after R5 stage.
[3] For these crops the maximum seasonal and per year application rates as shown.


Identification of specific data gaps:
      
The environmental fate data base for etoxazole was found to be adequate for a Tier 1 drinking water assessment.  In the Problem Formulation for Registration Review (DP Barcode 418231, dated 07/01/2014), aerobic and anaerobic aquatic metabolism studies were required.


Table 3. Etoxazole and Its Degradates/Residues of Concern
Registrant's Code
                       Chemical's Name and SMILES Code
                                   Structure
Etoxazole
IUPAC Name: (RS)-5-tert-butyl-2-[2-(2,6-difluorophenyl)4,5-dihydro-1,3-oxazole-4-yl] phenetole

CAS Name: 2-(2,6-difluorophenyl)4-[4-(1,1-demethylethyl) 2-ethoxyphenyl-4,5-dihydrooxazole

CAS No.: 153233-91-1

Formula: C21H23F2NO2
MW: 359.4 g/mol
                                       
                                       
R-8
2-amino-2-(4-tert-butyl-2-ethoxyphenyl)ethanol

SMILES Code: C(C1=C(C=C(C=C1)C(C)(C)C)OCC)(N([H])[H])CO[H]

Formula: C14H23NO2
MW: 237.34 g/mol
                                       
R-13
4-(4-tert-Butyl-2-ethoxyphenyl)-2-(2,6-difluorophenyl)-oxazole

SMILES Code: C1(=CC=CC(=C1C2=NC(=CO2)C3=C(C=C(C=C3)C(C)(C)C)OCC)F)F

Formula: C21H21F2NO2
MW: 357.40 g/mol
                                       

