UNITED STATES E NVIRONMENTAL PROTECTION AG E NCY WAS H INGTON D.C., 20460
OFFICE OF CHEM I CAL SAFETY AND POLLUTION PREVENT ION



### PC Code: 108501 DP Barcodes: 416208, 416209,416286 DATE : September 4, 2014 MEMORANDUM

SUBJECT: Pendimethalin: Drinking Water Assessment, and Ecological Risk Assessment for New Use on hops and multip l e crop group /s ubgroup conversions including Low Grow i ng Berry Subgroup 13-07G , Onion Subgroups 3

- 07 A & B , Sunflower Subgroup 2 0B , Citrus Fruit Group 10-10 , Pome Fruit Group 11-10, Stone Fruit Group 12

- 12, and Fruiting Vegetable Group 8

- 10.



### FROM: Ibrahim Abde l- Saheb, Ph.D. , Environmental Scientist

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# \~ Eli zabeth Donovan, Biologist

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# V'-1 Environmental Risk Branch 6 Env i ronmental Fate and Effects Divison (7507P) 

### THRU: Mark Corbin, Branch Chief A 

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# r**~** Environmental Risk Branch 6

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# V Environmental Fate and Effects Divison (7507P) 

### TO : Kab l e B. Davis, Product Manager Team 25 Emily Schmid , Ri s k Manager Reviewer Herbicide Branch Registration Division (7505P) Barbara Madden, Minor Use Team Leader Sidney J ackson , Risk Manager Reviewer Risk Integ ration , M i nor Use , and Emergency Response Branch Registration Division (7505P)EFED was asked to perfo rm a dri n ki n g water assessmen t ( D P Barcode (416286)), and an eco log ica l r is k assessment for th e her bi ci d e pendime th alin " Pro w l H20" (DP Ba r codes 4162 08 & 41 62 09 , EP A reg i stratio n No. 2 4 1

- 4 18 ) fo r a new use on hops a nd m u lti p le c r op gro up/subgro u p conversions incl ud i ng Low Growi ng Be r ry Su b gro u p 13-07G , O n ion S ub groups 3-07 A & B, Sunflower Subgroup 20B, Citrus Fruit Group 10-10, Pome Fruit Group 1 1-1 0, Stone Fruit Group 12-12 , and Fruiting Vegetable Group 8

- 10. None of the proposed uses ar e at a higher application rate than currently regi stered uses listed on label EPA Reg. No. 241-418. Thus; these subgroups are not assessed i n t hi s document. According to the pendimethal in new use petition, the maxim um single app l ication of Prowl 1

- bO is ei th er a single app l icat io n of 1 lb ai/acre or 4 l bs a i /ac re with se qu entia l applicatio n s w ith an i nte r va l of 30 days or mo re. Th e label li m it s the max im u m c um u lat ive total applicatio n rate to 4 lb ai/ac re o f Prowl H20 per year. On December 15 , 2010 ((DP B arcode 378514) , EFED completed Section 3 new use of pendimethalin on Edamame an d Cool- and Warm-Season Fo r age Grass ; with a maximum application rates 1.52 l bs a. i ./ acre to 4.00 lbs a. i ./ ac re , respect ively with an annua l max imum applicatio n rate of 4 lb ai /acre. Since the appl ica t ion rate for th e new p roposed u se o n ho p s is si mi la r to the prev i o u s l y assessed appli cat io n ra t e o f 4 l bs a.i./acre (2 010 Ri s k assess ment), t he proposed new u ses w ill y ie l d est imated exposure conce n trat io n s (EEC) simi l ar to those pr ese n ted in the 2010 grass assessment as shown i n Table 1 be l ow. T h us; whi le t h e current assessment yields slightly higher exposure and hence risk quotients (RQ) EFED be li eves that the risk profile for the current new use is substantially similar t o the risk profile in the earlier assessment
Tab le 1. Estimated Environme n ta l Concentratio n s ( p pb) for pend i m ethali n use o n ho p s.

20 10 20 14 Pea k ( 1- in-1 0 yr) 11. 9 12.7 21-day Avg ( 1
- in-1 0 yr) 4.13 3.34 60-day Avg ( 1-in-1 0 yr) 2.81 2.5 I

A s umm a r y o f that assessment fo llo ws. Based on the availab l e data, t he 2010 risk assessment concluded that pendimethalin is classified as highly tox i c to fish and aquatic invertebrates and slightly toxic to birds and mammals on an acute basis. On a chro nic basis , pendimethalin results in reduced egg p roduction in freshwate r fish an d reduced pr oduction of young i n freshwate r invertebrates. Chron ic tox ic ity data are not available for estuarine / marine fish and invertebrates. In terrestrial animals , chronic effects ofpendimethalin resul t in reduced avian body weight and dec reased number of pups born and pup weight in mammals. Pendimethalin is classified as practically non-to x ic to terrestrial insects. Base d on the availab le t e rres trial plant toxicit y data, pendimethalin is to xic to plants, with monocots havin g greate r se n s i ti vity to exposur e via see dlings, where as dicot s are more sensitive to ex po sure of fo li ar s urfaces.
Th e results of thi s screen in g- leve l r isk as sess m ent indicate that the proposed new uses of pendimethalin have the p ote ntial for d i rect acute effects to listed fr eshwater fish , est uarine / marine mollusks , and aquatic vascul ar and non-vascular plants (includ in g risk to non li sted aquatic no n- vascular p l ants)

. Although pendimethalin partiti ons to the sedi ment , risk s to benthic invertebrates ar e not expected becau se predicted sediment exposure co n centra tion s based on the proposed new uses are s ignificantly lowe r than sed im ent conc entration s where no effects w e re observed to mid ge larvae. With respect to te rr estrial ani mals , direct acute and chro ni c e ffect s to listed and non- li ste d birds and mammal s a r e poss ib le includin g chronic effects to piscivorous mammal s via in ges tion of pendim e th a lin residues in aquatic biota. ln addit i on, ri s k s to terrestrial plants ar e a l so predicted.
In addition , f or human health , the EFED Drinking Water memorandum for pendimethalin ( 0 33 4061 , 05 / 08/ 200 7) use on bearing grapes , cabbage , asparagus , and artic hoke y ie lds th e highest acute exposure co n centration of77.7**~-tg/ 1**  and the highest chroni c exposu r e concentration of 6 .00**~-t g/L.**  Es timat e d drink ing water concentrations (EDWCs) for thi s proposed S ection 3 new u se are no t expected to excee d the values for b earin g grapes, cabbage, a s p arag u s, a nd artic h oke

. Data gaps for this assessment include the followin g: No foliar d iss ipati on s t udies we re supplied b y the r egistrant. Th e re fore , the defa ult a ssumpti on foliar half-life of 35 days was u sed to calculate pend im ethalin re sidue concentrations o n te rrestrial food i tems. Pendi methalin is a persistent compound in some env ironments . Laboratory field di ss i p at ion stud ies in soil und e r aerob ic co ndition s dem o n strate a half

- life of appro ximately 72-17 2 days , and field dissipati on studie s in the Midwe st s imil a rl y s how half

li ves ranging from 84-147 days. lfthe foliar di ss ipation half-li fe is simi l ar to or greater than the availab le soil hal f-life data , the default a ssumption o f a 35-day half

- life m ay underestimate expos ure to terrestria l mammals and birds

. No chronic estuarine/ marine fish and non-m ollusk invertebrate data are avai lable for pendimethalin. All terrestrial plant te st ing was conducted with the active in gredien t (TGA I

- technical grade ac tive ingredient) and did not include solvent controls. The use of TEP (typica l end-use product) instead ofTGAI is reco mmended for all terrestrial non-target plant s tudie s. Testin g w ith only the TGAI may undere s ti m ate to x ic i ty to plants b ecause the TEP may includ e a so lv e nt or adjuvant whi c h results in additi ve o r syne rg is tic toxicity.
In add i tio n , s ince the prev ious risk assessment was pub li s hed , the Agency has issued guidance for the conduct and data needed to cond uct the ri sk assessment t o assess pesticide risk to bees (USE PA 

### e ta!. , 20 14 ). This guidance document indicates that if exposure of bees to a pesticid e isexpected , a Tier I screening-level risk assessment is conducted. The T ier I assessment is intended to be sufficiently conservative that chemicals that pass the screen are considered to represent a relatively low risk of adverse effects to bees. Tier I toxicity data that are generally needed to comp lete screening-lev e l risk assessments include acute contact toxicity data to adult honey bees (honey bees serving as a su rr ogate for all bee species), acute and chro nic oral toxicity to adult honey bees , and acute and chronic oral toxicity to juvenile (i.e. larval) honey bees. If risk concerns are identified in the screening

- level assessment, it may be refined using data that further define exposure or throu gh additional data including Tier II semi-field or fu ll -field toxici ty te sts. The current new use on hops and various crop group conversions include ground and aerial applications to a wide range of crops where spray drift may land on b loomin g non-target plants and could result in res idu es in pollen and nectar (which could then be transported to the hive). Additionally, pendimethalin is highly persistent and is system ic and can mov e in both xylem and phloem. A lthou gh pendimethalin u ptake is primarily through the foliage , root uptake is also po ss ible. Therefore , p end imethalin res idu es may be present in pollen and nectar e ither through transport from leaf tissues affected by spray drift o r f rom root uptake from plants grown where pend im ethalin was previously appl ied. Residues ca n in tum be brought back to bee colonies where in-hive bees including young adult and developing brood (i.e. , eggs , larvae and pupae) may be expos ed. Theref ore , exposure at all bee life stages would be expected.
S ince exposure of be es to pendimethalin residue s is expected, Tier I hon ey bee laboratory toxicity data are needed to conduct the scree nin g-level risk assessme n t. Ac u te contact toxicity data is ava il able that indicat e s p icloram residues are practically non-toxic to honey bees on an acute contact basis. How eve r , no data i s available that evaluate pendimethalin 's toxicity from the oral exposure route to adul t and larval bees on an acute or chronic basi s. Therefore , the Agency is requesting Tier I laboratory toxicity data for acute and chronic oral toxicity for both adult and la rval honey bees in order to complete the risk assessment for bees, as is further detailed in the attached data rationale tables. Should t he scree nin g level ri s k assessment identify that there are risk concerns to bees, mitigation measures may need to be co n side red or the regi s trant may conduc t Tier II effects studies (e.g. 850.3040 guideline studies) that reduce uncertainty by c haracterizing pendimethalin 's effects at the who l e-co lony l evel.



### References USEPA, PMRA and CDPR , 201 4. Guidance for Assessing Pesticid e Risks to Bees. Office of Pe s ticide Programs , USE PA , Washington D. C. Health Canada Pest Mana ge ment Regulatory Agency, Ottawa , ON, C anada. Cal iforni a Departm e nt of Pesticide Regulation , Sac ramento , CA. June 23, 2014.