UN I T ED STATES E NVIRON ME NTAL PROTECTION AGENCY WASHINGTON, D.C. 20 460



### MEMORANDUM
Date: October 29, 2013 OF FI CE OF CHEMICAL SA FETY AND POLLUTION PR EVENTION



### SUBJECT: Quizalofop-P-Ethyl: Review of Volatilization and Spray Drift Risk
PC Codes: 128709,128711 Decision No

. : 482699 Petition No.: NA Risk Assessment Type: NA TXRNo.: NA MRIDNo.: NA DP Barcode: D414696 Registration No. : 352-341 Regu latory Action: Registration Review Case No. : NA CAS No

. : 100646 -51-3 40 CFR: 180.441
FROM: Seyed Tadayon,

# Chemist**~** Risk Assessment Branch V Health Effec ts Division (7509P) Office of Pesticide Programs
THROUGH: MichaelS

. Metzger , Chief Risk Assessment Branch V Health Effects Division (7509P) Office o f Pesticide Programs
TO: Khue Nguyen, CRM Pesticide Re-evaluation Division (7508P) Office of Pesticide Programs

### I. ACTION REQUESTED
The Pesticide Re-evaluation Division has r equested a human health risk assessment for the potential exposures from volatilization and spray drift for various uses of quizal ofop

- p- ethy l. The most recent human health ri sk assessment for qu i zalofop-p-ethyl was completed on 12111112
as part of the registration review process (Quizalojop-P-Ethyl, Summary of Human Health Risk Assessmentfor Registration Review, 0394 1 92) and did not include an assessment of volatilization and spray drift. For details on hazard, tox i cology, and risk estimates for d i etary and occupational exposures see 0394192.


### II. CONCLUSION Spray drift and volatilization of quizal ofop

- p- et hyl from applications to crop and non-croplands do not resu lt in exposure risks of co n cern.


### III. DETAILED CONSIDERA TIONS
Quiza lofop

- p
-ethyl i s a selective herbicide used for the contro l of annual and perennial grasses i n crop- and non-croplands. Presently , qu i zalofop

- p
- ethyl is registered for uses on canola , crambe, cotton, dry beans, dry and succulent peas, l entils, mint, snap beans, soybean, sugar beets, barley, flax, sunflower and wheat. There are no residential uses
. Spray Drift
Off-ta r get movement of pesticides can occur via many types of pathways and i t is governed by a variety of factors. Sprays that are released and do not deposit in the application area end up offtarget and can lead to exposures to those it may directly contac t. They can also deposit on surfaces where contact wi th residues can eventually lead to indirect exposures (e

. g., children p l aying on l awns where r es i dues have deposited next to treated fie l ds). The potenti al risk es timates from these residues can be calculated using drift modeling coupled with methods employed fo r residential risk assessments fo r turf products. The approach to be used for quantitatively incorporating spray drift into risk assessment include assessing exposures for children ( 1 to 2 years old) and adults who have contact with turf where res idues are assumed to have deposited via spray drift thus resulting in an i ndirect exposure scenario. Aside from the p r edicted r es i dues avail able for transfe r , the routes of exposure and assessment methodology is analogo u s to how exposures to turf products are considered in risk assessment.
In order to evaluate th e d rift potential and associated risks, an approach based on drift mode li ng coupled with techniques used to evaluate residential turfuses of pesticides was utilized

. Essentially, a res i dential t urf assessment based on exposure to deposited residues has been c ompleted to address dri ft from the agricultural app li cations of quizalofop

- p- ethyl. In the spray dri ft scenario, the depos ited res i due value was determined based on the amount of spray drift that may occur at varying distances from the edge of the treated field using the AgD rift (v2

. 1 .1 ) mode l. Once th e deposited residue values were determined, the remainder of the spray driftassessment was based on th e algorithms and input values specified in the recently revised (20 12) Standard Operating Procedures for Residential Risk Assessment (SOPs).

A screeni ng approach was developed for situations w h ere specific label guidance fo r applicat i on parameters is not available

. 1• 2 AgDrift i s appropriate for use only when applicati ons are made by aircraft, airblast sprayers, and groundboom sprayer s
. When AgDrift was developed , a series of screening values (i.e., th e T i er 1 option) were incorporated into the mode l an d represe nt each equ ipmen t type and use under varied conditions

. The screening options specific all y recommended in this methodology were selected because the y ar e plausible and repr esen t a reasonable upper bound level of drift for common application methods in agricu lture. In all cases, each scenario is to be evaluated unless i t is n ot plaus ible based on the anticipated use pattern (e.g ., herb i c id es are not typ i cally applied to tree canopies) or spec i fic l abe l prohibi ti ons (e.g., aerial applications are not allowed).
Ri sk Estimates from Lawn Deposition Adj acent to Applications T he spray drift risk estimates are based on an estimated deposited residue concentration as a result of the sc reen in g level agric ultural app li cation scenarios. Quizalofop -p- ethy l is used on field crops and can be applied via aerial and groundboom equipments. Exposures were considered for 50 f eet w i de lawns where the nearest s ide of the property was di rectly adjo inin g the treated field (at fie ld edge) and at varied distances up to 300 fee t downwind of a treated fie ld

. Results are presented in T ab l e 1 and indicate that there are no risks of concern from aerial or groundboom applications at the field edge.
In addition to the screening leve l spray drift scenarios described above, additional results are prov id ed which r epresent viab l e drift reduction techno l og i es (DRTs) that represent potenti al risk management opt i ons. In particul ar, different spray qualities have been cons idered as well as the impact of other appl i cation co n ditions

. A dermal toxici ty endpoint was not selected for quizalofop -p- et h yl. Incidental oral ri sk estimates, using a chroni c oral e n dpo int (0.9 mg/kg/day) were used for this assessment. The applicab l e Level of Concern is 100 so MOEs < 100 would be of concern
. Chil dren's (1 <2 year o ld ) incidental oral r isk estimates are above 100 from indirect exposure to qui zalofop

- p
- ethyl relate d to spray d ri ft and therefore no buffer z one for aerial or ground boom app li cat i on s is required.

2http: //www.epa.gov/ ttnlscram / dispersion prefrec.htm 1 http: //www.epa.gov/ pesticides/science / residential-exposure-sop.html

### Volatilizatio n
Based on a WOE approach consid ering all t he availab l e hazard and exposure i nformati on for quizalofop, the HASPOC determined that a 28-day inhalation toxicity study in the rat is not r eq uired at this tim e
. This approach consider ed all the available hazard and e"fos ure information for quizalofop, includin g : (1) the low vapor pressure of quizalofop ( 8. 3 x 10- 1 mm Hg) ; (2) the low acute inhalation toxicity of quizalofop (Toxi city Category IV); and (3) the use of an oral POD established for the most sensitive endpoint / target organ system result ing in screening-level MOEs ranging from 2 , 900 to 211,000.

HED also believes that there is the p otential for bystander inhalation exposure to occur as a resu lt of volatilization of quizalofop

- p
- ethyl. Vo lati lization can occur during the app li cati on process or thereafter. It can resu lt from aerosols evaporating during application , while deposited sprays are still drying, or after as dried deposited residu es volatilize. Quantitative risk assessments for quizalofop

- p
- ethyl inhalation exposures have not been previous ly conducted b ecause no toxicologi cal endpoints were identified. Howev er, a Volatilizat ion Screeni ng Tool to esti mate bystander's risk was used for quizalofop-p-ethyl assuming that inhalation toxicity is equal to oral toxicity

. The screening too l util ized a number of physical and chemical properties to predict flux (e.g., t h e r ate at which a chemical vo l at ili zes off of a treate d fie ld ); the AERSCREEN m ode l to estimate ai r concentration s at different distanc es from a treated field; and chemical-specific human health toxicological data to estimate poten tial bystander inhalation risks. Using the screening tool , HED confirms that inhalation risks to bystanders from quizalofop-p-ethyl volatilization are not expected.1lc 1: Children Incidental Oral/Htl\1 Ri sk Su mmar y (MOE) rp/Rate Grou p S pra y T yp e/ Nozzle Ap p Rat e t:s t imate d At 10 feet 25 Fee t 5 0 Feet 75 Feet 100 Feet 12 5 F ee t ISO 200 Feet 250 Feet 300 Feet Co nfi g uration ( lb ai/A) or Edoe Feet Adjusted TTR, ( u

wc m2 ) 

### L

- > ·- .. .. Flax (The**hi g~est** **appli~!ion .**  rate

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_ 

## - _ . . ... 

## - - . I Aerial Fine to Medium 0

. 167 0.018 1 ,400 1,700 2, 100 2,700 3,600 4,700 5,600 6,600 8,600 10, 000 13,000 Medium 10 Coarse 1,700 2,300 3.100 4 , 300 6, 100 8 , 000 10 , 000 12 ,000 17 , 000 22 , 000 27,000 Coarse to Very Coarse 1, 900 2,900 4,300 6,700 9 , 600 13 , 000 16,000 20,000 27 , 000 35 , 000 44 , 000 Very Fine 10 Fine 950 1,000 1,200 1, 400 1, 600 1,800 2,000 2,300 2.800 3 ,300 3,700 AT40 1 , M, 10 mph , 37% SO 1, 500 1, 900 2,500 3 , 400 4 , 500 5 ,900 7,200 8 , 400 11 ,000 14 , 000 17,000 WASP, M, 1 0 mph , 37% SO 1,600 2 , 1 00 2,700 4. 1 00 5,600 7,200 8,800 10 ,000 14,000 17 , 000 20,000 AT401 , C

. 1 0 mph , 25% SD 1, 800 2,500 3,600 5,300 7,500 9, 800 12 ,000 15,000 21,000 2 7000 3 2 ,000 WASP, C, I 0 mph , 25% SO 2 , 1 00 2,900 4,200 6,700 9 , 300 1 3 , 000 15,000 20,000 27,000 35,000 39,000 AT4 0 1 , VC , 10 mph , 20% SO 2 ,000 3, 1 00 4 ,9 00 8,000 11 , 000 1 5,000 2 0,000 25,000 35,000 44 000 59,000 WASP , VC, 10 mph 20% SO 2,600 4 , 000 6.200 9.800 1 4 , 000 19,000 25 ,000 29,000 44 , 000 5 1,000 59 , 000 Grou ndboom H igjr Boom Ve rv lin e to Fine 1,900 3,800 6 ,3 00 1 0,000 14 , 000 18 , 000 21 , 000 25,000 32 , 000 44 ,000 51,000 Low B oo m Very fine to Fi ne 4, 200 11 , 000 1 8,000 27 000 35 , 000 44 , 000 51 ,00 0 59,000 7 1 000 88.000 120 ,000 High Boom F in e t o 7,200 19 ,000 27 , 000 39,000 5 1, 000 59,000 71,000 71 ,00 0 88 , 000 120 , 000 120 ,000 Med iurn!Coarsc Lo w Boom F ine 10 11 , 000 29,000 44 , 000 59,000 71 , 000 88 , 000 120,000 120 , 000 180 , 000 1 80 ,00 0 180, 000 Me dium/Coarse I Pineappl e
., ·- ··-·, I Aer ial Fine to Medium 0

. 21 0

.023 1, 1 00 1,300 1 ,700 2,200 2,900 3,700 4,500 5,200 6,900 8 ,3 00 10,000 Medium t o Coarse 1, 300 1 , 800 2,400 3,400 4 900 6,400 8 ,000 9,700 13,000 18 000 22,000 Coarse to V er

y Coarse 1 , 500 2,300 3.400 5 , 300 7 , 600 10, 000 13 , 000 16 , 000 22 000 28 , 000 35,000 Very Fine to Fin e 7 5 0 830 920 1 , 1 00 1, 200 1 ,400 1,600 1 ,800 2 , 200 2, 600 3,000 AT4 01 , M, l 0mph ,37%SO 1,2 00 1,50 0 2 ,0 00 2 , 700 3 , 600 4 , 700 5 , 700 6,700 8,800 1 1, 000 13 ,000 I WASP , M , 10 mph , 37% SD 1 , 300 1,600 2,200 3 ,300 4 , 500 5,700 7,000 8,300 11 , 000 13 , 000 16, 000 AT40 1, C, 1 0 mph , 25% SO 1 ,4 00 2 , 000 2,800 4 200 6.000 7, 800 9 , 700 12 , 000 17 000 22 , 000 26 ,000 WASP , C, 10 mph, 25%SO 1, 600 2,300 3 , 400 5 ,300 7 , 400 1 0,000 12, 000 16 , 000 22 , 000 28 , 000 31 , 000 A

T

401, VC , 10mph , 20%SO 1 , 600 2 ,400 3,900 6 ,400 9,100 12,000 16,000 20 ,000 28,000 35 , 000 47 , 000 WASP, VC, 10 mph , 20% SO 2,000 3,200 4,900 7 , 800 11 , 000 15,000 20 ,000 23,000 35 000 40 , 000 47 , 000 Groundboom HiJ! lr Boom VeT) • fin e to Firre 1, 500 3 , 000 5 , 000 8,000 11 ,000 14, 000 17,000 20 ,000 26,000 35 000 40,000 Low Boom Very fine to Fine 3,300 8 ,800 14 , 000 22,000 28 000 35,000 40,000 47,000 56 000 70 000 94 ,000 High Boom Fine to 5,700 15 , 000 22 , 000 31 , 000 40 ,000 47 ,000 56,000 56 ,000 70 ,000 94 , 000 94,000 Medium/Coarse Low Boom Fine to 8,500 23 ,000 35,000 47 , 000 56,000 70,000 94,000 94,000 140 ,000 140 , 000 140 , 000 M

edi um/Coa r se Vineyard 35 ,000 69,000 130 , 000 230 000 350,000 470 ,000

-·-- 560,000 700 , 000 940, 000 I , 400 ,000 1,400 ,000



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