UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , DC 204 60

O FF ICE OF CHE M I CAL S AFETY ANO PO LLU TIO N PREV ENTION

PC Code: 111 601 DP Barcode : 04 26 180 D a te : April 14 , 20 1 5
M E MORANDUM
S ubject:



### To:

From:

Thr o u g h : Response to Public Comments on the EFED R egis tration R ev iew Prob l em Formu lation for Oxy fl uorfen
B e nj a min Askin , C h e mi cal Review M a n age r Tom Moriarty , Team Leade r Nei l Anderson. Branch Chief Ri sk Management and Im p l eme ntation Branch l Pes ticide Re -Eva luation Div i s io n (7508P ) Meghan R adtke , P h .D. , Bi ologis t He Zhong , Ph .D ., Bi ologist E n v ironme nt al Risk B ranch I Environmenta l Fa te a nd Effects

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Office of P est ic ide Pro grams**~** S uj a th a Sankula , Ph .D

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# h .._U,.- h**~** E n v iron.ment a l Ri s k Bran c h I · En v ironm enta l Fate and Effects Di vision (750 7P ) Office of P esticide Programs
In respo n se to the preli min ary " Registrati o n Review P rob le m Formulation for Oxytluorfen " ( DP 4 1 94 1 9), D ow AgroSc iences LLC ( D AS) provided comme nt s du ri n g the public com ment peri od. The purpose of thi s m e m orandum i s to add r ess comments that are app li cab le to EF ED 's problem formulation.
DA S Co mment: T h e followin g s tudi es will be s ubmitted to furth e r c larify and update aquat ic ph otolys i s and d eg radate data: Yode r 2008 a nd Vo lk e l 200 7.
EFE D R es pon se: The Age n cy wil l r eview the s tudie s a nd incorp orate the inform at io n into future a naly ses, as a ppropriat e.

### DAS Co m me n t: Stud ies will be submitted to address the following data gaps: acute avian oral toxicity with a passerine species, acute oral adult hone ybee study, saltwate r fish acute toxicity , and saltwater fish early life-stage.


### EFE D Res p o nse: The Agency will review the studies a nd incorporate the information into future analyses, as appropriate. 

### DAS Co mm e n t : " However , in course texture sandy soils of low organic matter co nt ent , oxytluorfen has the potentia l to leach into s ha ll ow g roundwat e r les s than three m e ters deep (Yen et al. , 2003) " should be revised to read: Oxyfluorfen is not very mobile in soil and may not contaminate grou ndwater und e r normal conditions. However , in coarse texture sandy soils of extreme l y low organic matter content , oxytluorfen has th e potential to leach into sha ll ow gro undw ater le ss than thr ee meters deep (Ye n et al., 2003).


### EFE D R espo n se : T h e Agency believes it s paragraph in the Problem Fo rmul ation document adequately described the so il types an d m ob ility based on the su bmitted studies. To make c h anges as reque s ted, the Agency needs c larificati on fro m the registrant regarding " normal co nditi o n s " and the diff e r

e nc es between " n o rmal cond it ions" and " abnormal condit ions " in a field application s cenario.


### D AS Co mm e nt: " The chemical is unlikely to leach into groundwater , although limited vertica l mo ve ment through so il s may be p ossib le in sandy soils of low organ ic matter " should be revi s ed to read: Th e chemica l is unlikely to leach into grou nd wate r , a lth oug h limited ve rti ca l movement through so il s may be possible in sandy soils of 

### ext r e me ly low organic matter. 

### EFED R espo nse: Th e Agency believes its statement is justified. To add " extremely ," as requested , th e Agency ne e d s c larific at ion of the difference in classification between " low organic m atte r " and ' · extre m ely l ow organic matter .' · In addition , evidence must be provided to the Agency that oxytluorfen ha s n o vertical m ove m e nt in conditions of l ow organic m atter

. 

### D AS Co mm e nt: Larval honeybee toxic it y data, adu lt h oneybee chronic toxicity data, pollinator semi-field/feeding data , nect ar / pollen residue data , a nd field te s ting for pollinators s tudi es are n ot necessary because l) oxy fluorf e n i s not an insect growth regulator; and 2) there is low to no potential fo r exposure through product u se because crops w ith the highest uses (a lmond s , wine g rap es , pistachios , and wa lnut s) are e ithe r n ot attractive to honeybees and/or have restrictions on application timing with res pe ct to th e bloom of the crop , which would limit e xpo s ure to bees. In addition , for these crops , oxyfl u orfe n is only applied to th e weeds within the fields and not to the crop ca n opy because of the potential for serious injury to the crop. 

### EFE D R es p o ns e : EFED us es hon ey b ee d ata a s a s un- ogate for determining ri sk to a ll in sec t pollinators , not ju s t honeybees. Con s equen tl y, the Agency mu st co n sider a broader scope of pollinator behavior than just h o ne y b ees . For examp le , the tim es when non-h oneybee pollinators are act ive/ present may be different than hon ey b ees; likew ise , food item attractiveness may also differ.



### 2I) 

### Althoug h oxy flu o r fen is a n herb icid e and not an insect grow th regulator, it may s till have unintended to x ic ity to non-target o rgani s ms. Uninte nd ed tox icit y to n o n-tar ge t sp ec ies i s the basis for a ll of the testing required by EFE D. DAS asserts th at th e Schmi tzer 20 l l s tud y reports a 48 -hr LDso 

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### ai /bee, whic h would class ify oxyfluo rfen as " practically non - toxic " to adult honeybees , on an acute basis (note that this study has not been sub mitted to the Agency ye t and has no t undergone re view)

. This c la ss ifi ca tion is only re le va nt fo r ac ute exposure to adult bees and does not accou nt fo r the to x ic ity of a longer-term , lower dose exposure . Th e physiology of larv al and adult ho ne ybees i s diff erent , thus o ne li fe stage may be more sen s iti ve t o a p es ti c id e than the other. 2) Ox y fluorf e n is reg is te r ed on numerous outdoor uses in additi o n to th e almonds , wine g rapes , pi s tachios, and wa lnut s c ited by OAS. Uses inc lu de ag ri cultural , non-agricultural, and r esi denti a l pl ants and man y of the crops and ornamenta ls a r c considered attractive to pollin ato rs. DAS indicates that there are application timing re stric tion s that wo uld limit expos ure t o pollinators for almonds, w in e grapes, pi s tachio s , and walnut s; however , other uses do not have these restrictions and a complete ex posure pathway to honeybees an d othe r insect pollinators is possible. The Agency is co ncerne d not only about ri sks to bees visi tin g blooming cro p s or ornamentals, but also ex p os ure s th at occur as a result of s pr ay drift o nto a djac e nt bl oo min g weeds. Oxy fl uo rfen i s gene ra ll y only directly app li ed to weeds and not th e crop; however, if an y of th ose weeds are flow erin g, this wou ld res ult in a complete ex p osu re pathway. Application ty pes include direct s pray , spray , chemigati on, broadcas t, and band treatmen t , whi ch could res ult in spray dri f t. Oxyf1uorfen ma y drift to b loo min g non-target plants near th e s it e of appli cati o n and thus , exposure to in s ect pollinator s could occur. ln summary , EFE D be lie ves that there is a reasonable potential that insect pollinators m ay be exposed to oxy flu o rfe n. Adu lt ho n eybees may be ex pos ed o n a c hroni c basi s to oxyf1uorfen residues v i a pollen and nec tar. Larvae may be ex po se d through contaminated pollen an d nectar that are bro u gh t back to the hi ve. Co n se qu e ntl y, the a dult c hro nic and l a rv a l ac ute a nd c hr onic l a boratory toxicity tests are n ee ded to assess ri s k to b ees. Tier 2 (se mi

- fi eld / f ee din g data, residue s in poll e n/nectar) a nd Tier 3 (fi eld testing for p o llinato r s) st udi es m ay b e r eq uire d if t h e la b o r atory-generated toxicity data indicate ri s k co nc ern s for h on eybees.

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