Document ID: EPA-HQ-OPP-2015-0679-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2016-10-25T04:00Z

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

MEMORANDUM

DATE:	July 2, 2014

SUBJECT:	Tier I Estimated Drinking Waters Concentrations for the Special Local Needs (24(c)) use of Spirotetramat on Citrus in California in Bloom, to Control the Asian Citrus Psyllid [PC Code 392201; DP Barcode D420603]

FROM:	José L. Meléndez, Chemist
      Environmental Risk Branch V
      Environmental Fate and Effects Division

THROUGH:	Mah T. Shamim, Ph.D., Branch Chief
		Environmental Risk Branch V
		Environmental Fate and Effects Division (7507P)
		
TO:				Rita Kumar, Risk Manager Reviewer
				Reuben Baris, Environmental Scientist (Risk Manager #7)
				Meredith Laws, Branch Chief
				Insecticide-Rodenticide Branch
	Registration Division (7505P)

AND:			Julie VanAlstine, Environmental Health Scientist
				Dana Vogel, Acting Branch Chief
				Registration Action Branch I
		Health Effects Division (7509P)

      This memorandum presents the Environmental Fate and Effects Division's (EFED) Tier I Estimated Drinking Water Concentrations (EDWCs) for spirotetramat (CAS No. 203313-25-1), and for two of its major transformation products spirotetramat-enol and spirotetramat-ketohydroxy, for use in the human health risk assessment by the Health Effects Division (HED).  The registrant has applied for a proposed Special Local Needs (Section 24(c)) use of spirotetramat on citrus.  The proposed use specifically targets Asian citrus psyllid on citrus during bloom periods.  Spirotetramat is already registered on citrus at the same application rate, against the same pest, as the proposed Section 24(c) label (a maximum application rate of 0.16 lb a.i./A/app, with two applications allowed per year, refer to Table 2).  The only difference between the labels is that the Section 24(c) label allows applications during the blooming period.

      EFED reviewed the petition and found that previously issued drinking water analyses (DWAs) provide suitable information for use by HED.
 Firstly a DWA evaluated the uses on watercress (for surface water), and bananas and plantains (for groundwater), includes the uses with the potential highest exposure, with an application rate of up to 0.4-1.25 lb a.i./A/season (DP Barcode D398507, dated 07/19/2012).
 Second, a previous review (DP Barcode D410121; dated 05/03/2013), provides information relative to groundwater using the new model PRZM-GW v.1.0 to model groundwater.
 Finally, the 2012 and 2013 DWAs relied heavily on a 2008 assessment (DP Barcode D345275, dated 01/22/2008) in that the summary of the environmental fate and physicochemical properties and characterization, chemical structures of spirotetramat and its metabolites, approaches, and several other details about spirotetramat were reported.

      The 2012 DWA provided the EDWC for surface waters (using FIRST and the Tier 1 Rice Model) and groundwater (SCI-GROW) and focused on changes in EDWCs, compared to the review dated 2008.  The 2013 review provided information about PRZM-GW groundwater runs.

      Using the Tier 1 aquatic models SCI-GROW v.2.3 and PRZM-GW v.1.0 (groundwater, for the use on bananas and plantains), and the Tier 1 Rice Model v.1.0 (surface water, used as a surrogate model for the use of spirotetramat on watercress), it was found that watercress at an application rate of 0.4 lb a.i./A/season (surface water) and bananas and plantains at 1.25 lb a.i./A/season (groundwater using PRZM-GW v.1.0), were the uses involving the highest potential exposure.  For the total toxic residues (spirotetramat + spirotetramat-enol + spirotetramat-ketohydroxy), the acute and chronic EDWC in surface water is 395 ppb.  Further, the EDWC in groundwater is 7.99 ppb for the highest daily value, and 5.36 ppb for the post-breakthrough average (Table 1).
      
      Spirotetramat is a systemic broad spectrum tetramic acid insecticide (ketoenol class) that is applied as a preventative treatment during an early threshold of developing chewing insect population when sufficient leaf tissue is present for uptake and translocation to occur within agricultural crops.  The mode of action for spirotetramat is lipid biosynthesis inhibition (LBI); it belongs in the Group 23 Insecticides.  Residue exposure to surface water is typically possible through surface water runoff, soil erosion and/or off-target spray drift.  The mobility of spirotetramat is moderately high (Kd range 3.58-5.52 L/Kg, KOC range 184-437 L/KgOC, classified as moderately mobile, FAO 2000).  Spirotetramat is labile, especially under aerobic soil metabolism conditions.  Nonetheless, its total residues are relatively persistent than the parent alone.

      The Tier 1 EDWCs for spirotetramat and for its major transformation products spirotetramat-enol and spirotetramat-ketohydroxy (per HED's request in DP Barcodes D333437 and D345276, dated 05/14/2008), were calculated using the Tier 1 Rice Model v.1.0 (surface water, as a surrogate for applications to watercress), and SCI-GROW v.2.3 and PRZM-GW v.1.0 (groundwater, applications on bananas and plantains) for use in the human health risk assessment.
      
      Table 1 provides a summary of the Tier I modeled drinking water concentrations.  This DWA presents screening level EDWCs for the use of spirotetramat.  A more definitive assessment could be performed, using the Tier II aquatic model SWCC.  Should any questions arise, please, contact EFED or José Meléndez at melendez.jose@epa.gov.

Table 1.  Maximum Tier I Estimated Drinking Water Concentrations (EDWCs) for drinking water risk assessment based on ground or aerial application of spirotetramat on plantains and bananas (for groundwater) at 1.25 lb a.i./A/season, and ground, aerial or chemigation applications on watercress (for surface water) at 0.4 lb a.i./A/season.
Drinking Water Source (Model)

                Estimated Drinking Water Concentration  (EDWC)

Chemical:
                                    Parent
                                 Spirotetramat
                              Spirotetramat-enol
                           Spirotetramat-ketohydroxy
                         Total Toxic Residues (TTR)[1]

Risk \ Units
                                     (ppb)
                                     (ppb)
                                     (ppb)
                                     (ppb)
Ground-water (PRZM-GW, for WI sand[2])
Highest Daily Value
                                      ~0
                                      ~0
                                     7.99
                                     7.99

Post-Breakthrough Average
                                      ~0
                                      ~0
                                     5.36
                                     5.36
Surface Water (Tier 1 Rice Model v.1.0)
Acute and Chronic[3]
                                      N/A
                                      N/A
                                      N/A
                                      395
 TTR = Total Toxic Residues (sum of spirotetramat + spirotetramat-enol + spirotetramat-ketohydroxy)
[2] It is acknowledged that plantains and bananas are not grown in WI; however, as a Tier 1 tool, PRZM-GW was run with the scenario that has the highest potential exposure.  Refinements are available, should they be required.
[3] Surface-water concentrations calculated by the Tier I Rice Model v1.0 and ground water concentrations calculated by SCI-GROW do not distinguish between peak and chronic concentrations.

Use Characterization

	Table 2 is a summary of the use pattern for spirotetramat in the proposed Section 24(c) label for Movento(R) Insecticide.  The proposed new use pattern allows applications during the blooming period while previously the label had the following restriction: "Do not apply this product within 1 0 days prior to bloom, during bloom, or until petal fall is complete."  Pest targeted for control is the Asian citrus psyllid.  An inspection of Table 2 shows that the current Section 3 label has the same application rate and interval between applications, with a seasonal rate of 0.31 lb a.i./A/year, applied foliarly.  In contrast, higher rates of 0.4-1.25 lb a.i./A/season were assessed for watercress, and bananas and plantains, in a memorandum dated 07/19/2012 from J. Meléndez to L. Nollen and J. VanAlstine (DP Barcode D398507).  Table 2 is based on the proposed Section 24(c) label.

Table 2. Summary use information for spirotetramat based on the S24(c) label for MOVENTO[(R)] (EPA Reg. No. 264-1050)
                                      USE
                  SINGLE  APP. RATE             (lb. a.i./A)
                                NUMBER OF APPS.
                        SEASONAL APP. RATE (lb. a.i./A)
                         INTERVAL BETWEEN APPS. (days)
                                  APP. METHOD
                                  PHI (days)
Citrus[1][, 2]
                                     0.16
                                       2
                                     0.32
                                      21
                                G*, A, Airblast
                                       1
[1] Citrus Fruits  -  Crops of Crop Group 10-10 Including: Australian lime (desert, finger, and round), Brown River finger lime, Calamondin, Citron, Grapefruit, Japanese summer grapefruit, Kumquat, Lemon, Lime, Mediterranean mandarin, Mount White lime, New Guinea wild lime, Orange (sour and sweet), Pummelo, Russell River lime, Satsuma mandarin, Sweet lime, Tachibana orange, Tahiti lime, Tangelo, Tangerine, Tangor, Trifoliate orange, Uniq fruit, including cultivars, varieties and/or hybrids of these commodities.
[2] May be applied during the blooming period.

Identification of specific data gaps

      The environmental fate database for spirotetramat is substantially complete.  At this time, no additional data has been required.

Previous DWAs for Spirotetramat

Tier I Drinking Water Concentrations of the New Chemical Spirotetramat and Its Transformation Products for the Use in the Human Health Risk Assessment for the Registration of the Food Uses on Citrus Fruits (Crop Group 10), Grapes and Small Fruit Climbing (except kiwifruit), Pome Fruits (Crop Group 11), Stone Fruits (Crop Group 12), Tree Nuts (Crop Group 14 plus Pistachio), Hops, Christmas Trees, Cucurbit Vegetables (Crop Group 9), Fruiting Vegetables (Crop Group 8 plus Okra), Leafy Vegetables (Crop Group 4), Brassica (Cole) Leafy Vegetables (Crop Group 5), and Potatoes and Other Tuberous and Corm Vegetables (Crop Subgroup 1C); DP Barcode D345275, dated 01/22/2008.

Tier I Estimated Drinking Waters Concentrations (EDWCs) of Spirotetramat and its Transformation Products for the Use in the Human Health Risk Assessment for the Section 3 New Uses on Several New Crops; DP Barcode D398507, dated 07/19/2012.

Tier I Estimated Drinking Waters Concentrations of Spirotetramat and its Transformation Products, for the Use in the Human Health Risk Assessment for the Proposed New Section 3 Residential Uses; DP Barcode D410121, dated 05/07/2013.

References

Food and Agriculture Organization of the United Nations.  FAO PESTICIDE DISPOSAL SERIES 8.  Assessing Soil Contamination: A Reference Manual.  Appendix 2. Parameters of pesticides that influence processes in the soil.  Editorial Group, FAO Information Division: Rome, 2000. http://www.fao.org/DOCREP/003/X2570E/X2570E00.htm (accessed 04/09/2013).