UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D

.C., 20460



### PC Code: 112602 DPBarcode: D423472 Date: November 18,2014
MEMORANDUM
SUBJECT:

TO:

FROM: Response to Public Comments on the Trinexapac-ethyl Proposed Interim Decision BrittanyPruitt, Chemical ReviewManager Avivah Jakob,Team Leader Patricia Parrott, Branch Chief Risk Management and Implementation Branch III 

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# 1 Environmental RiskBranch I · Environmental Fate and Effects Division (7507P) OfficeofPesticidePrograms

In response to the Proposed InterimDecisionforTrinexapac-ethyl (casenumber7228), Syngenta CropProtection submitted two comments regarding the ecological risk assessment in supportof Registration Review (D409748) and the Environmental Fate arid Effects Division response to public comments on therisk assessment (D416981). This memo addresses Syngenta's comments inthe contextofthe proposed interim decision. 

### Syngenta's Comment: As perthe EPA response to Public Commentsdocument (DP Barcode: D416981), Page 3,Residues ofConcern, EPAResponse #2, "Onlythose degradates identified in the abiotic hydrolysis studyatpH 7 are included in the total toxic residue (TR) abiotic hydrolysis half-life." Syngenta believesthatthe major degradation products included in the TTR, CGA313458 and M3, will only form under acidic conditions (MRID

### 46809301); and therefore should not be included as partofthe stressor ofconcern. 

### EFEDResponse: As mentioned in the Agency's response, "onlythose degradates identified in the abiotic hydrolysis studyatpH7 are included inthe total toxicresidue (TR) expression", the unidentified degradate M3, will not be includedtheTRcalculation, since it is formed atpH 5. 

### The degradate CGA-313458 

### will beincluded into the tolerance expression as itfonns in theaqueous photol ys i s st udy (M RID 46809302) and ha s been identified as a degradate of concern by the Residues of Concern Knowledgebase Subcommittee (ROCKS) of EPA's Health Effects Division (HED) (0390 1 2 1 ). Syngenta's Comment: Syngenta comment to t h e EPA Response to Public Comments document (DP Barcode: 0416981 ), page 5 , T -REX Modeling, EPA Response # 16 regarding the potential exposure of birds to granules on corn versus turf e n viro nment s: Granules may be ingested accidentally when birds forage for food or they may be ingested intentionally if they are mistaken for food (e.g. , grains and weed seeds) o r whe n birds are foraging for grit. Sy ngenta cited the example from Fisher and Bes t (Environ. Toxicol. And Chern. 11:1495-1508, 1995) to represen t a reasonab l e worst-case scenario where birds may indiscriminately consume granules while selecting for grit in a field with s ufficient bare ground. EPA suggested that turf is expected to contain l ess bare ground and, t h ere for e, have less available natural grit. In EPA's response to comments, the Agency also provided useful citations from ECOFRAM on the Granule Grit Preference factor. In the EPA response it is discussed that birds could be more likely to selectively take up granules as grit in a turf scenar io vs. bare

gro und. How ever, Best (Nationa l Wildlife Research Center Repell ents Con f ere nce 1995) stated that birds greatly favo r silica granules for grit rather t han much softer g ranular products that are

co mpri sed of gypsum or clay

( http: // digitalcommons.unl.edu/cgi/viewcontent.cgi?article = 1 005&context=nwrcrepellants ). The preferable silica granules are read il y availab l e on bare so ils , as indi cated by EPA, or, for turf applications, in sand traps found on golf courses. In addition, granules applied on turf areas of go lf courses are less visible than those on bare g round. Erbach et al. (Transactions of the ASAE 39: 11-15. , 1996) demonstrated that, within o n e h ou r after applicati o n , o nl y 67% of granules were visible o n greens and on l y 38% and 15% of granules were visible on fairways and rough , respectively. Visibility dec r eased further upon irrigation. These fmdings by Best (1995) and Erbach et al. (1996) support the discussion that granule consumption by b i rds on golf courses would be less t han that on bare ground. Thi s limit ed exposure, in addition to the relatively low toxicity oftrinexapac-ethyl to birds, indicate s that ri sk to avian species from consumption of granules is correspondingly low.

EFED Response: The LDs o/ ff analysis is u sed to estimate the dose that a bird receives through all potentially comple t e exposure routes. The most obvious exposure routes include direct ingestion of gra nule s as gr it o r incidental ingestion of granules as a matter of course during feedi ng or preening. However, granules are a mechanism to deliver trinexapac-ethyl to turf and consequently it is reasonab l e to expect that the pesticide will be released fr om the granules to the

surrounding environment. Therefore, exposure is a l so possible throu gh I ) in gestio n of pesticide residues in animal and vegetative food item s through uptake o f a pe st icid e from granule-released pesticide in t h e soil matrix , 2) direct dermal contact with gran ul es and pe s ticide released to t h e soi l matrix, 3) consumption of pesticide with drinking water in contact with pesticide granu l es or pesticide released to so il or vegetative matter, and 4) inhala t ion of dust o r vapor phase pesticide. The informa tion about gr it size arid locati on may help refine the assessment for some specific exposure routes (i.e. direct ingestion for granules as gr it ), but the information does not address o th er potentially co mpl e t e exposure routes. In the absence of data r egard in g the other possible routes of exposure that wo uld preclude them as being complete, EFE D ca nn ot rely sole l y on the 2informationprovided to set aside the LD50/ft2 analysis. Further, trinexapac-ethyl is registered forturf , which may include landscapesot herthan golfcourses (e.g., residential yards, parks, recreational areas, and businesspar ks) and the provided analysis is silentaboutthe completeness ofanyexposure routes for these potential sites.

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