UN I TED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D

. C

., 20460

OFFICE OF CHEMICAL SAFETY AND POLLUT I ON PREVENT I ON



### PC Code: 128965 DP Ba r code: 407817 Date: March 28, 20123

MEMORANDUM

SUBJECT:

TO:·



### FROM: Spray Drift Analysis for the Etofenprox Label Amendment (Petitio n No

. 1£7925)

Andrew Ertman, Ri sk Manager Reviewer Barbara Madden

, Ri sk Manager Minor Use Team Registration Division (7505P)

Kristin Rury, Biologist Christine Olinger, Branch Chief Risk Assessment Branch III Health Effects Division (7509P)

Chuck Peck, Environmental Engineer Envi r on mental Risk Bran ch IV Environmenta l Fate and Effects Division (7507P)

REVIEWI;J> Jim Carleton, Ph.D., Senior Scientist BY: 

# x ·**~** En vironmental Risk Branch IV Environ mental Fate and Effects Division**(7~7P)** 

# f

Faruque Khan, Ph.D., Senior Scie nti st /

# c:::v-~ 

# C--t--- 3/ :2.& / 

## I 

# .J

Environmental Risk Branch I Environmental Fate and Effects Division (7507P)



### APPROVED Marietta Echeverria, Branch Chief BY: Environmental Risk Branch IV Environmental Fate and Effects Division (7507P)

This memorandum addresses the IR -4 submission in s upport of tolerance requests for etofenprox. In particular, IR-4 ha s requested to amend the labels for Zenivex E20 (Reg. No. 2724-791) to and Zenivex E4 RTU (Reg. No. 2724-807) allow for ultra

- low volume (UL V) s pra y applications over "agricu ltural crops ( i nclu ding t hose intend ed for human consumption)

, pasture a n d rangeland. " In support of this effort, IR-4 subm itted a magnit ud e of residue study and modeli n g to evaluate residues over aeriall y applied crops. IR-4 also submitted information to support the s upp osition that residues resulting from ground UL V app l ications could be extrapolated from aerial UL V application deposition data. This memorandum addresses both aspects of the IR4 submission. Additionally, the results from this analysis are in good agreement with HED's assessment (DP Barcode 405380).



### 1

### 2 Summary: A raw agricultural commodity (RAC) stud y was conducted by the IR-4 program in which a single treatment of etofenprox was completed using aerial equipment typical of mosquito adulticide applications. 1 Investigators used AGDISP to identify the locations outside of the treated area where residues were expected to be the highest, given the environmental conditions at the time of application. RACs were sampled in these locations. The submission addressed how the AGDISP computations were completed in order to define these sampling locations.

In addition, IR-4 submitted rationale that the residues found in the RAC study, following aerial application, could be used as a basis for comple ting a risk assessment for ground-based mosquito adulticide applications ( i.e. , deposition from ground applications is similar to that from aerial applications). A number of literature studies were reviewed by the author s, as was a dissertation focused on the mechanistic aspects of drift fro m ground-based adulticide applications. The findings of these analyses indicated that depositi on from ground-based applications were similar in to depositions monitored during aerial applications.

However, there is some uncertainty as to how representative the deposition results were for minimum conditions specified on the etofenprox a dulticide labels, based on the meteorological conditions and the number of applications occurri ng at the RAC study sites. Current labels stipulate that applications can occur during wind speed conditions ranging from 1 to 10 mph, and that up to 25 treatments can be completed within a single year. While the application conditions in the RAC studies were typical of what would be expected under normal application situations, only one application was performed rather than th e maximum number allowed by the labels. As a result, the residue levels could be higher than those measured, as etofenprox deposition could potentially be higher than what occurred in the study.

The results of the analysis conducted by EFED in dicate that a deposition rate of 33% for sprays reaching agricultural crops is a conservativ e estimation for both ground (based on submitted literature data) and aerial (based on AGDISP m odeling) ULV applications based on the label guidance for etofenprox. The maximum deposition value from the ground ULV literature was consistent with the modeling results also pr esented in the submission. The conservative deposition value helps account for some of the unc ertainty associated with deposition values that could not be estimated from data provided in some of the studies. These values assume a minimum wind speed of 1 mph. If the wind speed was increased to 2 mph, the deposition rates would decrease to 20% (based on AGDISP modeling) for aerial ULV applications and 24% (based on Schleier model) for ground ULV applications. Table 1 depicts the deposition rates and estimated residues for aerial and ground ULV applications with minimum wind speeds of 1 and 2 mph. 

### Table 1. Deposition Rates and Residue Levels for Aerial and Ground ULV Applications of Etofenprox
1 mph wind speed 2 mph wind speed Application Type Deposition (%) Residue (ppm) Deposition (%) Residue (ppm) Aerial 33 4.3 – 4.8 20 2.6 – 2.9 Ground 33 4.3 – 4.8 24 3.1 – 3.5

1 MRID 48612201.

### 3 Introduction

IR-4 has requested a label amendment for Zenive x E20 and Zenivex E4 RTU to allow for ultralow volume (ULV) spray applications over agri cultural crops (including those intended for human consumption), pasture and rangeland. These end use products are insecticides used at low volumes to control adult mosquitoes, non-biting mi dges, and biting and non-biting flies. Zenivex E20 and Zenivex E4 RTU can be applied via aerial or ground ULV application at a rate of 0.007 lbs a.i./A, 25 times per site per year, for a maximum annual application rate of 0.18 lbs a.i./A/year. These products do not have tolerances , however, nor are they currently allowed for use over general cropland areas. The purpose of this action is to evaluate the methodology and data submitted by IR-4 to support such a use pattern. When applied aerially, existing and the proposed label changes stipulate that spray equi pment must be adjusted so that the volume median diameter (VMD) is less than 60 microns (Dv 0.5 < 60 μm) and 90% of the spray is contained in droplets smaller than 100 microns (Dv 0.9 < 100 μm). Aerial applications must occur at heights greater than 100 feet, preferably between 100 and 300 feet, and wind speeds must be between 1 and 10 mph. No swath width is sp ecified, but based on the assessment conducted by IR-4, swath width for aerial applications is assume d to be 500 feet. For ground ULV applications via cold aerosol sprayers, the Zenivex E20 a nd Zenivex E4 RTU labels specify that spray equipment must be adjusted so that the VMD is between 10 and 30 microns (10 μm ≤ Dv 0.5 ≤ 30 μm) and 90% of the spray is contained in droplets smaller than 50 microns (Dv 0.9 < 50 μm). Wind speeds must be between 1 and 10 mph and a swat h width of 300 feet is recommended. Per the Zenivex E20 label and Zenivex E4 RTU labels, thermal fogging equipment mounted on a truck can also be used with a VMD less than 60 microns (Dv 0.5 < 60 μm) and 90% of the spray is contained in droplets smaller than 100 microns (Dv 0.9 < 100 μm).

Aerial ULV Application

In order to support a label modification to a llow for ULV applications of etofenprox over pastureland and crops, IR-4 conducted a magni tude-of-residue study, using aerial ultralow volume (ULV) applications of etofenprox (Zenivex E20) over pasture grass, leaf lettuce, alfalfa, and snap beans in California and Florida (MRID 48612201). In each case, a single application at 0.007 lbs a.i./A was made. The maximum residue reported for an application at a 100-foot release height (required by the label for aerial UL V applications) was 0.17 ppm on leaf lettuce at the Florida site. The maximum residue reported for an application at a much lower release height (50 feet) was 0.39 ppm on pasture grass at the Califor nia site. It should be noted that the 50-foot release height is not allowed under the cu rrent Zenivex E20 and Zenivex E4 RTU labels 2

. To estimate the residues resulting from multiple app lications, IR-4 used the TREX model. The model uses the Kenaga Nomagram to calculate the residues on avian and mammalian food items, using the application rate and the dissipation ra te of a chemical applied to foliar surfaces. Assuming a single application rate of 0.007 lbs a. i./A, a default dissipation rate of 35 days, and that 100% of the applied pesticide deposited on the crop, TREX estimates a maximum residue level (short grass) of 1.68 ppm, roughly 10 times higher than the residues measured at the Florida site in the study. To achieve the levels obser ved at the Florida site in the residue study, an application rate of 7.08x10 -4 lbs a.i./A, or 10% of the application rate, would need to be used in TREX. Given that the wind speed at the Florid a site ranged from 0 to 2.5 mph, the observed application efficiency of approximately 10% appears reasonably consistent with AGDISP predictions for aerial ULV application (see discussion below). Therefore, use of an application

2 MRID 48612201.

### 4 rate of 7.08x10 -4 lbs a.i./A for etofenprox in TREX is c onsistent with both observed and predicted deposition data.

EFED evaluated aerial ULV applications of et ofenprox using the mode l AGDISP version 8.25 ( Appendix A ). Given the same application parameters ( e.g. , drop size distribution, application material, application height), model results i ndicate that deposition is sensitive to wind speed as an input parameter. Etofenprox can be applied when wind speeds range from 1 to 10 mph. For a wind speed of 1 mph, the application efficiency, or the percent of pesticide depositing on the crop, is 33%. As wind speed increases, th e deposition within the swath decreases. The deposition inside the swath drops to 2.2% and 0% at a wind speeds of 2.5 and 3 mph, respectively. It should be noted that in running AGDISP, two warning messages occurred: (1) the spray volume (0.005 gal/A) was beyond the reco mmended range of 0.25 to 30 gal/A, and (2) the swath width (500 ft) was beyond the recommended ra nge of 15 to 100 ft. While the values for spray volume and swath width were taken fro m the study (MRID 48612201) and appear to generate deposition residues in line with the st udy results, they are outside the recommended range of the model and the modeled deposition estimates are characterized as uncertain.

IR-4 then used this application rate (7.08x10 -4 lbs a.i./A) in TREX to model multiple applications. Per their submission (pg. 19), the IR-4 proposed the following: Four applications, at the maximum label rate, per 30

‐ day period (i.e. 4 applications + a 26

‐ day rest period), would be unlikely to exce ed 1.5 ppm peak residue using reasonably conservative assumptions. Restricting the labe l to 3 applications per week (i.e. no more than 3 applications at any site in any 7 day period, and no more than 4 applications at any site in any 30 day period) would provide a greater safety margin.

EFED evaluated the proposed multiple applica tion scenarios using TREX and confirmed the calculation of estimated residues predicted by IR-4 . For the proposed four applications scenario, the maximum residue level (short grass) from TREX was 1.46 ppm. For the proposed three applications scenario, the maximum residue level (short grass) from TREX was 1.32 ppm.

For comparison purposes, EFED also evaluated th e residues for deposition rates of 33% (worst case wind speed of 1 mph) and 20% (wind speed of 2 mph). The application rates increased from 7.08x10 -4 lbs/A to 2.31x10 -3 and 1.4x10 -3 lbs/A for deposition rates of 33 and 20%, respectively. For the proposed four applications scenario, the maximum residue levels (short grass) from TREX increased to 4.77 and 2.89 ppm for depositio n rates of 33 and 20%, respectively. For the proposed three applications scenario, the maximum residue levels (short grass) from TREX increase to 4.32 and 2.62 ppm for deposition rates of 33 and 20%, respectively. In both cases, the increases were proportional to the in creases in application efficiency.

Ground ULV Application

IR-4 has suggested that the surface deposition of pesticide residues following ground ULV application will be similar to that resulting from aer ial ULV application. IR-4 has also suggested that to reduce the risk of exceeding proposed to lerances, label requirements of a minimum wind speed of 2 mph during application, and a 25 f oot buffer zone between the spray equipment and the agricultural commodities for gr ound-based ULV application of et ofenprox may be warranted. To support these arguments, IR-4 submitted the following: a literature review on deposition from ground ULV applications; a review of aerial deposition using the AGDISP spray drift model; a summary of model results for ground ULV depos ition from a recent dissertation (Schleier, 2012); and, worst-case deposition estimates based on physics-based modeling. A discussion of each of these supporting arguments is provided below. It s hould be noted that while EFED evaluated the

### 5 deposition of ground ULV applications at wind speeds of 2 mph, it may not be feasible to implement this as a label condition.

According to communications with IR-4 (email from Dr. Karl Malamud-Roam, Public Health Pesticides Program Manager, IR-4 Project Headquarters, 2/8/2013), ground-based ULV applications typically occur in neighborhoods on the fringe of agricultural areas, with potential drift occurring onto agricultural areas. Mosquito control districts treating neighborhoods typically drive up each street, then turn and make a pass on the next street ( i.e., one pass per block-wide swath). Drift from more distant passe s is possible into agricultural areas, but is assumed to be attenuated by the buffering distance of the block (typically assumed to be 300 feet) and by the houses, trees, and other obstacles ty pical of urban/suburban areas. While ground ULV applications can occur in more rural areas ( e.g. , larger fields devoid of obstacles hindering drift) as well as suburban areas with smaller blocks ( e.g. , OPP’s Health Effects Division currently uses 50 feet wide lawns for their residential spray drift assessments), as the purpose of ground ULV applications is to maintain the adulticide in th e air, a 300-foot swath was considered a typical value for this assessment.

Literature Review

IR-4 submitted eight published studies on ground ULV application, in which pesticide deposition was measured. IR-4 concluded that, based on the results of these studies, ground ULV deposition values are similar to results that have been reported for aerial ULV applications.

EFED has reviewed these studies (DP Barcode 407 817, 03/11/2013) and has determined that up to 33% of the nominal application rate of an active ingredient may be deposited on surfaces. However, it should be noted that in three of the studies the deposition rate, as a percentage of the application rate, could not be determined, as an ac curate application rate could not be ascertained from the study. The highest deposition rates, obtained in the Knepper et al. (1996) study, were 1- 2 orders of magnitude higher than those in the other studies. The study used grass clippings to evaluate deposition, unlike the other studies that t ypically employed flat cloth, paper, or metal dosimeters. As the grass has th e ability to capture droplets in the horizontal and vertical directions, unlike flat coupons which collect depos ition only in the horizontal direction, this may explain why the Knepper deposition results are hi gher. Additionally, wind speeds were low (1 mph), increasing the likelihood of deposition rates higher than the other studies. An application rate could not be determined from the study, so it is unclear what percentage of the applied pesticide was deposited on the grass. A summa ry of the deposition values is provided in Table 2

. An analysis of the available deposition percenta ges indicates that the 90 percent upper confidence limit on the mean value is 8.7% (average of 7.1%, n=94).



### Table 2. Peak deposition rates repor ted in ground ULV literature studies

Reference /

Number Material Peak deposition

(ng/cm 2 ) Peak deposition (% applied) 1 Distance from application source to peak deposition (m) Wind speed (mph)

Tucker et al 1987 Fenthion 2.92 2 8 Not reported Malathion 85.8 15 8 Not reported Naled 57.3 20 8 Not reported Moore et al 1993 Malathion 84.1 14 30.4 0.9 – 3.4

Tietze et al 1994 Malathion 50 9 5 2.1 – 4.0

### 6 Reference /

Number Material Peak deposition

(ng/cm 2 ) Peak deposition (% applied) 1 Distance from application source to peak deposition (m) Wind speed (mph)

Knepper et al 1996 Malathion 9,222 NA 7.6 1 Permethrin 14,389 NA 7.6 1 Tietze et al 1996 Malathion 473 NA Unknown 0 – 2.5

Schleier and Peterson 2010 Naled 74 33 50 1.5 Permethrin 4.6 5.9 25 4.3 Pierce et al 2005 Permethrin 5.1 10 Unknown 6 - 12

Preftakes et al 2011 Permethrin 8 10 25-50 m 4.8

1. NA – insufficient information to assess.

AGDISP Modeling

In an effort to depict the impact of meteor ological conditions on deposition, IR-4 conducted a number of model runs using the AGDISP version 8. 15. In prior work, IR-4 used the AgDISP model to predict potential aerial ULV deposition for use in establishing flight-lines for their magnitude-of-residue study. Using th e results of this analysis ( Figure 1 ), IR-4 concluded that the relationship between deposition and distance from the application source was strongly dependent on wind speed, with peak deposition decreasing dramatically as wind speed increases from 0.5 mph to 1.0 mph, and a less dramatic decrease as wind speed increases from 1 to 2 mph. While the analysis was conducted for aerial ULV app lications, and EFED does not use the AgDISP model for estimating deposition fro m ground applications, neverthel ess IR-4 concluded that the impact in changing wind speeds would be similar for ground ULV applications.

Figure 1. Deposition from Aerial ULV Applications, IR-4 AGDISP Modeling

### 7 Using the input parameters provided by IR -4 (Appendix A of the IR-4 submission, Appendix B in this document), EFED ran AGDISP, but was not able to replicate the deposition pattern depicted in Figure 1 . Results from EFED modeling using IR -4’s input parameters and AGDISP version 8.25 are depicted in Figures 2 (g/m 2 versus distance, similar to units depicted in Figure 1 ) and 3 (percent applied versus distance). While the EFED modeled deposition rates are higher than those obtained by IR-4, the general trend th at deposition in the application area (-500 to 0 ft) decreased with increased wind sp eed was observed. As wind sp eed increased, the amount that deposited from the point of application to the distan ce of the swath width (500 ft) also decreased, with a deposition rate of 46% at 0.5 mph to 9% at 1 mph to 0% at wind speeds greater than 3 mph. It should be noted that the application efficiency for the 1 mph wind speed run (9%) is lower than the 33% modeled in the Aerial ULV Application section above. The D v0.5 in these model runs was set to 28 microns, per IR-4 pa rameters, as opposed to the maximum aerial D v0.5 of 60 microns specified on the label, which was used in the Aerial ULV Application model runs.

0.00E+00 1.00E

‐ 04 2.00E

‐ 04 3.00E

‐ 04 4.00E

‐ 04 5.00E

‐ 04 6.00E

‐ 04

‐ 500

‐ 300

‐ 100 100 300 500 700 900Deposition(g/m2)

Distance from Downwind Edge of Swath (ft) 

## Figure 2. Deposition in Application Area and Beyond

0.5 mph 1.0 mph 2.0 mph 2.5 mph 3.0 mph

### 8 ULV Spray Drift Modeling (Schleier 2012)

In addition to the studies cited in the literatu re review described above for ground-based ULV applications, additional information was su bmitted to support the premise that ground ULV deposition rates can be conservatively estimated using aerial ULV deposition estimates of 10- 30% of the amount applied. IR-4 submitted a recent dissertation (Schleier, 2012) on ground ULV applications and a model developed based on the study results. A brief summary of Schleier 2012 is provided in Appendix C . IR-4 used the model developed in the dissertation paper to estimate deposition of etofenprox following ground ULV applications in different wind speeds. The range of model deposition results for a typi cal 300 foot swath downwind of spray equipment was 8 to 18 ng/cm 2 , or 10-23% deposition rate of an app lication of etofenprox at 0.007 lbs/A (0.007 lb/A = 78.5 ng/cm 2 ). This is similar to the rate est imated from the magnitude of residue study following an aerial application of etofenprox.

Using the parameters specified in the IR-4 submission ( Table 3 and Appendix C ), EFED ran the Schleier model and was able to duplicate the deposition results estimated by IR-4 ( Figure 4 ) for a D v0.5 of 22 μm. Deposition rates ranged from 11 to 22% across the 300 foot (90 meter) swath, with an average deposition rate across the swath of 16% for all wind speeds. If the D v0.5 was increased to 30 μm (the maximum D v0.5 specified on the label) and all other input parameters were held constant, depos ition rates would range from 16 to 33% across a 300 foot swath, with an average deposition rate of 24% for wind speeds ranging from 1 to 10 mph. For both 1 and 2 mph wind speeds, deposition rates ranged from 21 to 27%. It should be noted that, based on the data 0% 10% 20% 30% 40% 50% 60% 70%

‐ 500

‐ 300

‐ 100 100 300 500 700 900Deposition(%)

Distance from Downwind Edge of Swath (ft) 

## Figure 3. Deposition in Application Area and Beyond

0.5 mph 1.0 mph 2.0 mph 2.5 mph 3.0 mph

### 9 in Schleier 2012, there did not appear to be a clear relationship between the count median diameter (CMD) and VMD, so the CMD was not changed.

Table 3. Input Parameters Used in IR-4 Modeling

Parameter Application Rate (g/ha) Flow Rate (ml/min) Density (g/ml) CMD ( μ m) VMD ( μ m) Temperature (oC) RH (%) Stability

Value 7.846 192 0.891 1.36 22 22 50 2 (neutral)

Physics-based Modeling

As the current spray drift models (AGDISP and AgDRIFT) employed by EFED are not capable of estimating deposition from ground-based ULV a pplications, IR-4 used a simple Newtonian model to estimate downwind travel distance fo r the ground ULV applications. Using the following equation, based on Stoke’s Law, (USEPA 2010) , the terminal velocity of a particle can be estimated, which in turn can be used to es timate travel time and downwind distance for the particle, assuming relatively stable atmospheric conditions 0.00E+00 2.00E+00 4.00E+00 6.00E+00 8.00E+00 1.00E+01 1.20E+01 1.40E+01 1.60E+01 1.80E+01 2.00E+01

0 50 100 150 200Deposition(ng/cm2)

Distance (m) 

## Figure 4. ULV Deposition, Shleier Model 2012

1 mph 2 mph 3 mph 4 mph 5 mph

6 mph 7 mph 8 mph 9 mph 10 mph

### 10 ݒ ௧ ൌ ߩ ݔ ݃ ௣ ݀ ݔ ௦௣ ଶ ܥ ݔ ௖ ߤ ݔ 18 Where

v t = terminal settling velocity (cm/s) g = acceleration due to gravity (980 cm/s 2 )
ρ p = density of particle (0.891 g/cm 3 ) d ps = Stokes particle diameter (cm) C c = Cunningham slip correction factor (unitless, 1) μ = viscosity of air (1.82x10 -4 g/cm-s)

For a 1 meter release height, IR-4 estimated the downwind travel distance for a number of particle sizes that encompass the si ze of particles in ground ULV sprays ( Table 4 ). EFED verified these calculations, and concurs that this would be representative of worst case settling conditions, as more unstable conditions would cause the adultic ide aerosol to dilute and ascend out of the target area (Bonds, 2012). According to Bonds, 20 12, “neutral to weakly stable conditions are considered ideal for ULV spraying”. As su ch, EFED would expect these estimations, modeled during steady state wind flow, to be similar to those estimates derived in the literature studies, which were primarily conducted at dusk, when neutral to stable conditions are expected to exist (Bonds, 2012).

The cumulative drop size distribution (DSD) column reflects the percentage of droplets below the specified drop diameter, assuming a DSD where the D v0.5 was 30 microns and the relative span ( e.g. , the breadth of the drop size distribution, or [D v0.9 -D v0.1 ]/D v0.5 ) was 1.14. These specifications closely match the specifications on the Zenivex E20 label, where the D v0.5 must be less than or equal to 30 microns and 90% of the particles must be less than 50 microns in diameter. The deposition rate column is 100% minus the cumulative DSD. Based on the deposition rates, EFED estimated the percentage of droplets settling within 300 feet (or the swath width) of the application source using the above equation.



### Table 4. Newtonian Modeling Results of Gr ound ULV Deposition, Release Height 1 Meter
Drop Diameter

(μm) Diameter (cm) Velocity (cm/s) Time (s) Distance (ft) Cumulative DSD % Deposition Rate (%) Wind speed (mph)

1 2 3 5 10
8 0.0008 0.171 586.22 859.8 1719.6 2579.4 4299.0 8598.1 1.6 98.4

10 0.001 0.267 375.18 550.3 1100.6 1650.8 2751.4 5502.8 2.9 97.1

15 0.0015 0.600 166.75 244.6 489.1 733.7 1222.8 2445.7 9.7 90.3

20 0.002 1.066 93.80 137.6 275.1 412.7 687.8 1375.7 20.8 79.2

25 0.0025 1.666 60.03 88.0 176.1 264.1 440.2 880.4 34.9 65.1

30 0.003 2.399 41.69 61.1 122.3 183.4 305.7 611.4 50.0 50.0

40 0.004 4.265 23.45 34.4 68.8 103.2 172.0 343.9 75.5 24.5

50 0.005 6.663 15.01 22.0 44.0 66.0 110.1 220.1 90.2 9.8

60 0.006 9.595 10.42 15.3 30.6 45.9 76.4 152.9 96.8 3.2

70 0.007 13.060 7.66 11.2 22.5 33.7 56.2 112.3 99.1 0.9

80 0.008 17.058 5.86 8.6 17.2 25.8 43.0 86.0 99.8 0.2

### 11 % DSD Settling within 200 ft of application 86 69 53 30 8 % DSD Settling within 300 ft of application 92 81 69 49 19

Assuming a wind speed of 2 mph, a D v0.5 of 22 microns (approximate midpoint of D v0.5 requirements for etofenprox), and a release height of 1 meter, IR-4 estimated that 10% of the etofenprox deposits in the firs t 44 feet (the red value in Table 4 ) and 50% in the first 200 feet (the approximate midpoint of the two blue values in Table 4 ). The Zenivex E20 label requires the D v.09 (or 10% of the drops) to be less than or eq ual to 50 microns for ground spray. Using Table 4 , the distance at the intersection of 50 microns a nd a wind speed of 2 mph is 44 feet. Likewise, if the D v50 (or 50% of the drops) equals 22 microns, the distance for a wind speed of 2 mph lies approximately midway between 176 and 275 feet, or around 200 feet.

Assuming a wind speed of 2 mph, a D v0.5 of 30 microns, and a release height of 1 meter, EFED confirmed that approximately 10% of the etofenprox residue deposits in the first 44 feet (the red value in Table 4 ), but that 69% deposits in the first 200 feet and 81% in the first 300 feet (the green values in Table 4 ). The 69% is estimated by inter polating between the deposition rate for 176.1 feet (65.1%) and the deposition rate for 275 .1 feet (79.2%) to determine the deposition estimate at 200 feet. Likewise, the 81% is estimat ed by interpolating between deposition rate for 275.1 feet (79.2%) and the deposition rate for 489 .1 feet (90.3%) to determine the deposition estimate at 300 feet.

For comparison purposes, a release height of 10 feet (3.05 m), the minimum height of the adult mosquito habitat cited by IR-4 (page 23 of submission), was also modeled ( Table 5 ). Assuming a wind speed of 2 mph and D v0.5 of 30 microns, EFED estimated that that 23% of the etofenprox deposits in the first 200 feet and 39% in the first 300 feet (the green values reported in Table 5 ), which is slightly higher than the 33% reported in the literature studies. Values were estimated as discussed above.

It should be noted that the percentages deve loped above are deposition rates for the entire distance specified and do not reflect the deposition at any particular point. For instance, the 39% reported in Table 5 is the deposition over the entire 300 foot width, and not the deposition specifically at the 300 foot distance, which would be expected to be smaller.



### Table 5. Newtonian Modeling Results of Ground ULV Deposition, Release Height 3.05 Meter (10 feet)

Drop Diameter

(μm) Diameter (cm) Velocity (cm/s) Time (s) Distance (ft) Cumulative DSD % Deposition Rate (%) Wind speed (mph)
1 2 3 5 10

8 0.0008 0.171 1787 2620.7 5241.4 7862.1 13103.5 26206.9 1.6 98.4

10 0.001 0.267 1144 1677.2 3354.5 5031.7 8386.2 16772.4 2.9 97.1

15 0.0015 0.600 508.2 745.4 1490.9 2236.3 3727.2 7454.4 9.7 90.3

20 0.002 1.066 285.9 419.3 838.6 1257.9 2096.6 4193.1 20.8 79.2

25 0.0025 1.666 183.0 268.4 536.7 805.1 1341.8 2683.6 34.9 65.1

30 0.003 2.399 127.1 186.4 372.7 559.1 931.8 1863.6 50.0 50.0

40 0.004 4.265 71.47 104.8 209.7 314.5 524.1 1048.3 75.5 24.5

50 0.005 6.663 45.74 67.1 134.2 201.3 335.4 670.9 90.2 9.8

60 0.006 9.595 31.77 46.6 93.2 139.8 233.0 465.9 96.8 3.2

### 12 70 0.007 13.060 23.34 34.2 68.5 102.7 171.1 342.3 99.1 0.9

80 0.008 17.058 17.87 26.2 52.4 78.6 131.0 262.1 99.8 0.2

% DSD Settling within 200 ft of application 53 23 10 2 0 % DSD Settling within 300 ft of application 68 39 23 8 1

Discussion and Conclusions

IR-4 has requested a label amendment for Ze nivex E20 and Zenivex E4 RTU (Reg. No. 2724- 807) to allow for ultra-low volume (ULV) spray a pplications over agricultural crops (including those intended for human consumption), pasture and rangeland. Zenive x E20 and Zenivex E4 RTU can be applied via aerial or ground ULV appl ication at a rate of 0.007 lbs a.i./A, 25 times per site per year, for a maximum annual applicati on rate of 0.18 lbs a.i./A/year. These products do not have tolerances, however, nor are they currently allowed for use over general cropland areas. The purpose of this action is to evalua te the methodology and data submitted by IR-4 to support such a use pattern. IR-4 has submitted a residue study for aerial ULV applications over pasture grass, leaf lettuce, alfalfa, and snap beans in California and Florida. The maximum residue levels corresponded to approximately 10% of the amount of pesticide applied. Aerial ULV deposition data from the residue study and AGDISP modeling suggests that deposition values will typically be in the range from 10 to 33% of the amount of pesticide applied for wind speeds between 1 and 3 mph. IR-4 has posite d that pesticide deposition resulting from ground ULV applications will be similar to that resulting from aerial ULV applications, but has also proposed that, to reduce the risk of exceedi ng proposed tolerances, for ground-based ULV applications a minimum wind speed of 2 mph and a 25 foot buffer zone between the spray equipment and the agricultural commodities ma y be warranted. EFED has evaluated the supporting documentation ( e.g. , literature studies, AGDISP modeling, dissertation modeling, and physics-based modeling) and agrees that they su pport the contention that ground ULV deposition rates at wind speeds greater than 2 mph are co mparable to those associated with aerial ULV application ( e.g. , deposition ≤ 33% of the amount applied). However, not all of the deposition rates could be estimated for the submitted literature studies ( e.g. , Knepper et al. , 1996), so it is possible that the maximum deposition rate c ould be higher than 33%. In cases where the application height of etofenprox is lower than 10 feet (the minimum mosquito habitat), there is also the potential for more material to deposit (50-70%, 200 feet from the application source, based on simple Newtonian modeling at a 1 meter high release height).

Overall Conclusions

Based on the current label specifications, EFED concludes that 33% (based on AGDISP modeling) is a conservative estimation for depositi on resulting from aerial ULV applications and that 33% (maximum value reported in the s ubmitted literature studies) is a conservative estimation for deposition resulting from ground ULV applications. The maximum value from the ground ULV literature was c onsistent with the modeling results also presented in the submission. The conservative value helps account for some of the uncertainty associated with deposition values that could not be estimated from data pr ovided in some of the studies. These values assume a minimum wind speed of 1 mph. If the wind speed was increased to 2 mph, the deposition rates would drop to 20% (based on AGDISP modeling) for aerial ILV applications and 24% for ground ULV applications (based on Schleier model). Residue estimates based on these deposition rates were determined using the TREX model and are presented in Table 1 of this report.

### 13 References

MRID 48612201-01. Dorschner, K. 2011. Etofenprox: Magnitude of residue on alfalfa, bean foliage, pasture grass, and leaf lettuce. IR-4 Project Headquarters, Princeton, NJ.

Bonds, J.A.S. 2012. Ultra-low volume space sprays in mo squito control: a critical review

. Medical and Veterinary Entomology 26:121-130 ( 

### http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2915.2011.00992.x/pdf)

Knepper, R.G., Walker, E.D., et al. 1996. Deposition of malathion and permethrin on sod grass after single, ultra-low volume applications in suburban neighborhood in Michigan . J Am Mosq Control Assoc 12:45-51

Moore, J.C., Dukes, J.C., Clark, J.R., Malone, J., Hallmon, C.F., Hester, P.G. 1993. Downwind drift and deposition of malathion on human target s from ground ultralow volume mosquito
sprays . J Am Mosq Control Assoc 9:138-142

Pierce, M.C., R.H., Henry, M.S., Blum, T.C., Mueller, E.M. 2005. Aerial and tidal transport of mosquito control pesticides into the Florida Keys National Marine Sanctuary . Revista de Biologia Tropical. 53:117-125

Preftakes, C.J., Schleier, J.J. III, Peterson, R.K.D. 2011. Bystander exposure to ultra-low volume insecticide applications used fo r adult mosquito management . International Journal of Environmental Research and Public Health, 8:2142-2152

Schleier, J. III and Peterson, R. 2010. Deposition and air concentrations of permethrin and naled used for adult mosquito management . Archives of Environmental Contamination and Toxicology. 58(1):105-111

Schleier, J. III. 2012. Development of an environmental fate model for risk assessment of ultralow volume insecticides . Dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral of Philosophy in Ecolog y and Environmental Sciences, Montana State University. April 2012

Tietze, N.S., Hester, P.G., and Shaffer, K.R.. 1994. Mass recovery of malathion in simulated open field mosquito adulticide tests . Archives of Environmental Contamination and Toxicology 26:473-477

Tietze, N.S., Hester, P.G., Shaffer, K.R., and Wakefield, F.T. 1996. Peridomestic deposition of ultra-low volume malathion app lied as a mosquito adulticide. Bulletin of Environmental Contamination and Toxicology. 56:210-218

Tucker, J., Thompson, C., Wang, T., and Lenahan, R. 1987. Toxicity of organophosphorus insecticides to estuarine copepods an d young fish after field applications . J Florida AntiMosquito Association 58:1-6

USEPA. 2010. Basic Concepts in Environmental Scie nces, Module 3: Characteristics of Particles - Collection Mechanisms ( http://www.epa.gov/apti/bces/module3/collect/collect.htm ). USEPA’s Office of Air and Radiation, Air Quality Planning and Standards, Air Pollution Training Institute. Updated January 29, 2010.

### 14 Appendix A. EPA Input Parameters used in AGDISP Modeling

AGDISP Input Data Summary

Title: Etofenprox aerial copter ULV 1 mph
Notes:

Calculations Done: Yes Run ID: AGDISP etofenprox aerial copter ulv 1 mph.ag 8.25 01-29-2013 14:29:40

--APPLICATION METHOD-- ---------------------------- Method Aerial --Aircraft-- ---------------------------- Name Aerodyne Wasp Type Library Wing Type Helicopter Rotor Radius (ft) 17.4 Weight (lbs) 2090 Typical Speed (mph) 61.99 Rotor RPM 320 --Spray Lines-- ---------------------------- Release Height (ft) 100 Spray Lines 1 Optimize Spray Reps No Spray Line Reps # Reps 1 1

--APPLICATION TECHNIQUE-- ---------------------------- Application Technique Liquid --Nozzles-- ---------------------------- Boom Length (%) 0 Nozzle Locations # Hor(ft) Ver(ft) Fwd(ft) 1 0 0 0

--Drop Size Distribution-- ----------------------------
Name ULV Type User-defined Drop Categories # Diam (um) Frac 1 5.09 0.0010 2 10.22 0.0036 3 15.38 0.0092 4 20.58 0.0183 5 25.81 0.0303 6 31.08 0.0435 7 36.38 0.0563 8 41.72 0.0673 9 47.10 0.0759 10 52.51 0.0815 11 57.96 0.0830 12 63.45 0.0803 13 68.98 0.0763 14 74.54 0.0692 15 80.14 0.0608 16 85.78 0.0521 17 91.46 0.0436 18 97.18 0.0357 19 102.94 0.0286 20 108.73 0.0224 21 114.57 0.0171 22 120.45 0.0128 23 126.36 0.0094 24 132.32 0.0067 25 138.32 0.0048

### 15 26 144.36 0.0033 27 150.44 0.0023 28 156.56 0.0016 29 162.73 0.0011 30 168.93 0.0007 31 175.18 0.0005

--SWATH-- ---------------------------- Swath Width 500 ft Swath Displacement 0 ft

--METEOROLOGY-- ---------------------------- Wind Speed (mph) 1 Wind Direction (deg) -90 Temperature (deg F) 65 Relative Humidity (%) 50

--SPRAY MATERIAL-- ---------------------------- Name Etofenprox Spray Material Evaporates No Spray Volume Rate (gal/ac) 0.005 Active Fraction 0.2 Nonvolatile Fraction 0.99 Active Fraction of Tank Mix 0.2 Fraction of Active Solution that is Nonvolatile 1 Additive Fraction of Tank Mix 0.79 Fraction of Additive Solution that is Nonvolatile 1

--ATMOSPHERIC STABILITY-- ---------------------------- Atmospheric Stability Overcast

--SURFACE-- ---------------------------- Upslope Angle (deg) 0 Sideslope Angle (deg) 0 --Canopy-- ---------------------------- Type None Surface Roughness (ft) 0.0246

--TRANSPORT-- ---------------------------- Flux Plane Distance (ft) 0

--ADVANCED SETTINGS-- ---------------------------- Wind Speed Height (ft) 6.56 Max Compute Time (sec) 600 Max Downwind Dist (ft) 2608.24 Vortex Decay Rate (OGE) (mph) 0.3355 Vortex Decay Rate (IGE) (mph) 1.25 Aircraft Drag Coeff 0.1 Propeller Efficiency 0.8 Ambient Pressure (in hg) 29.91 Ground Reference (ft) 0 Save Trajectory Files No Half Boom No Default Swath Offset 0 Swath Specific Gravity (Carrier) 0.891 Specific Gravity (Active/Additive) 0.891 Evaporation Rate (μm2/deg C/sec) 84.76

### 16 AGDISP Input Data Summary

Title: Etofenprox Aerial 1 mph
Notes:

Calculations Done: Yes Run ID: AGDISP aerial ulv 1 mph.ag 8.25 01-30-2013 13:07:51

--APPLICATION METHOD-- ---------------------------- Method Aerial --Aircraft-- ---------------------------- Name Hiller FH-1100 Type Library Wing Type Helicopter Rotor Radius (ft) 17.7 Weight (lbs) 2073 Typical Speed (mph) 68.99 Rotor RPM 394 --Spray Lines-- ---------------------------- Release Height (ft) 50 Spray Lines 1 Optimize Spray Reps No Spray Line Reps # Reps 1 1

--APPLICATION TECHNIQUE-- ---------------------------- Application Technique Liquid --Nozzles-- ---------------------------- Boom Length (%) 50 Nozzle Locations # Hor(ft) Ver(ft) Fwd(ft) 1 -8.85 0 0

--Drop Size Distribution-- ----------------------------
Name ULV Type User-defined Drop Categories # Diam (um) Frac 1 2.49 0.0010 2 4.99 0.0038 3 7.49 0.0099 4 10.01 0.0199 5 12.54 0.0328 6 15.07 0.0468 7 17.61 0.0600 8 20.17 0.0711 9 22.73 0.0792 10 25.30 0.0839 11 27.88 0.0839 12 30.48 0.0805 13 33.08 0.0752 14 35.69 0.0673 15 38.30 0.0584 16 40.93 0.0495 17 43.57 0.0410 18 46.22 0.0333 19 48.88 0.0264 20 51.55 0.0205 21 54.22 0.0156 22 56.91 0.0116 23 59.61 0.0085 24 62.31 0.0061 25 65.03 0.0043 26 67.76 0.0030 27 70.49 0.0021

### 17 28 73.24 0.0014 29 76.00 0.0010 30 78.76 0.0007 31 81.54 0.0005 32 84.32 0.0010

--SWATH-- ---------------------------- Swath Width 500 ft Swath Displacement 0 ft

--METEOROLOGY-- ---------------------------- Wind Speed (mph) 1 Wind Direction (deg) -90 Temperature (deg F) 77.9 Relative Humidity (%) 55.44

--SPRAY MATERIAL-- ---------------------------- Name Etofenprox Spray Material Evaporates No Spray Volume Rate (gal/ac) 0.005 Active Fraction 0.2 Nonvolatile Fraction 1 Active Fraction of Tank Mix 0.2 Fraction of Active Solution that is Nonvolatile 1 Additive Fraction of Tank Mix 0.8 Fraction of Additive Solution that is Nonvolatile 1

--ATMOSPHERIC STABILITY-- ---------------------------- Atmospheric Stability Slight

--SURFACE-- ---------------------------- Upslope Angle (deg) 0 Sideslope Angle (deg) 0 --Canopy-- ---------------------------- Type None Surface Roughness (ft) 0.0246

--TRANSPORT-- ---------------------------- Flux Plane Distance (ft) 0

--ADVANCED SETTINGS-- ---------------------------- Wind Speed Height (ft) 6.56 Max Compute Time (sec) 600 Max Downwind Dist (ft) 2608.24 Vortex Decay Rate (OGE) (mph) 0.3355 Vortex Decay Rate (IGE) (mph) 1.25 Aircraft Drag Coeff 0.1 Propeller Efficiency 0.8 Ambient Pressure (in hg) 29.91 Ground Reference (ft) 0 Save Trajectory Files No Half Boom No Default Swath Offset 0 Swath Specific Gravity (Carrier) 0.8 Specific Gravity (Active/Additive) 0.8 Evaporation Rate (μm2/deg C/sec) 84.76

### 18 Appendix B. AGDISP Input Parameters for IR-4 Modeling

### 19

### 20 Appendix C. Summary of Schleier, J. 2012. Development of an Environmental Fate Model for Risk Assessment of Ultra-low Volume Insecticides . Dissertation, Montana State University. April 2012

The objectives of the dissertation were to perform field studies to measure environmental concentrations of insecticides applied using grou nd ultra-low volume spray in order to develop a validated model to predict the deposition of UL V insecticides, and use the data generated from the field study to perform refined human and aquatic ecological risk assessments. A regression model selected by a Bayesian Information Crite rion and k-fold cross validation was used to validate the selected model.

Deposition experiments were conducted near El k Grove, California, Bozeman, Montana, and Baton Rouge, Louisiana during the summers of 2009 to 2011. Sites with little vegetative structure and flat topography were chosen for a ll experiments, to minimize vegetation affects on air movement and subsequent deposition. Sit es were 200-m long with two lines of horizontal drift collectors positioned 25 m to the left and right of the center of the plot to capture variability of deposition within the spray plot ( Figure C-1 ). Samples were averaged together at each distance from the spray source for statistical analys is. Sampling occurred at distances of 5, 10, 15, 20, 30, 35, 40, 50, 60, 65, 70, 75, 80, 90, 95, 100, 110, 120, 125, 130, 135, 140, 155, 160, and 180 m from the spray source.

During all applications, the truck speed was 16.1 km /h (10 mph). Applications occurred when the prevailing wind was blowing perpendicular to the collection site ( Figure C-1 ). Sprays were conducted using a Guardian 95 ES (ADAPCO, Sa nford, FL, USA) in Montana and a London Fogger model 18 (London Fog Inc., Long Lake, MN, USA) in California and Louisiana. Nozzle orientation of the sprayers was +45° angle compar ed to the horizon which is the most commonly used angle for mosquito management. Between each spray replication the nozzle, pump, and hoses were rinsed with 300 ml of D.I. H 2 O followed by 300 ml of a 1:1 mixture of high pressure liquid chromatography acetone (99.7% purity; EMD Chemicals, Gibbstown, NJ, USA) and American Chemical Society (ACS) grade tolu ene (99.5% purity, Mallinckrodt Baker, Inc., Phillipsburg, NJ, USA) (Schleier III et al. 2010).

### 21 Figure C-1. Plot Layout for Schleier 2012 Study

The oil-based insecticides Permanone® 30-30 (30% permethrin), Scourge® 18+54 (18% resmethrin), Permanone® 31-66 ( 31% permethrin) (Bayer Envir onmental Science, Research Triangle Park, NC, USA), Zenivex® E20 (20% etofenprox) (Central Life Sciences®, Schaumburg, IL, USA), and PyronylTM Crop Spra y (6% pyrethrins) (Prentiss Inc., Alpharetta, GA, USA) were used. The water-based formul ations Aqua-Reslin® (20% permethrin) (Bayer Environmental Science, Research Triangle Park, NC, USA) and Aqua-Kontrol (20% permethrin) (Univar®, Redmond, WA, USA) were used. Th e active ingredients were applied at the maximum rate of 7.85 g/ha of active ingredient according to label for all insecticides, except for Pyronyl Crop Spray which was applied at the ma ximum rate of 2.8 g/ha of active ingredient.

The experimental design was a complete random ized design with each formulation randomly selected for the order when it was sprayed. Re plications were performed over time within the same night and over different nights with a total of 96 spray events occurring during the three field seasons. Applications began no earlier than 18:00 h at all locations, with most applications occurring after 20:00 h. Glass Petri dishes (15-cm diameter) were used to collect deposition at ground level. Cardboard was staked to the gr ound to provide a level surface for the glass Petri dishes. One glass Petri dish was placed on each piece of cardboard at ground level and collected 10 minutes after the application. Fluorescent tracers were used to determine the concentrations of insecticide. The oil-soluble tracer Tinopal OB (BASF Corp., Florham Park, NJ, USA) was mixed with all oil-based formulations at a rate of 11 g/L and the water-soluble tracer Fluorescein (Aqua Solutions, Deer Park, TX, USA) was mixed with all water-based formulations at a rate of 14 g/L. For all applications, a maximum of 1-L of formul ation was mixed with the tracer in a Nalgene 1- L narrow mouth high density polyethylene bottle (F ischer Scientific, Pittsburgh, PA, USA) to ensure that the tracer was adequate ly mixed into the formulation.

### 22 Petri dishes were extracted with 15 ml of toluene or D.I. H 2 O for Tinopal OB and Fluorescence, respectively. The liquid was decanted into an alysis vials which were wiped with KimWipes (Kimberly-Clark® Global Sales, LLC, Roswell, GA, USA) to remove fingerprints and dry the vials before analysis. After extraction, Petr i dishes were rinsed with toluene or D.I. H 2 O, depending on the tracer used, then rinsed with high pressure liquid chromatography acetone.

A GFL-1A fluorometer (Opti-Sciences, Inc., Huds on, NH, USA) was used to detect the amount of light absorbed at a specific wavelength which represented the amount of tracer present in the sample. For the detection of Fluorescence, the s ource filter was 465 nm and the detection filter was 530 nm. For the detection of Tinopal OB, the source filter was 370 nm and the detection filter was 430 nm. Standard curves were prepared using serial dilutions prepared in toluene and D.I. H 2 O for Tinopal OB and fluorescen ce, respectively. Absorbance was re corded for each sample representing the concentration of the insec ticide. The detection limits for Tinopal OB and Fluorescence were 0.0001 2 and 0.000015 μg/cm 2 , respectively. The detection limits for waterand oil-based insecticides were 0.00076 and 0.0002 μg/cm 2 , respectively.

A DC-III portable droplet measurement system (KLD Labs, Inc., Huntington Station, NY, USA) was used to measure droplet spectra of each fo rmulation at all locations. The DC-III probe was held 2 m from the nozzle in the center of the sp ray plume and sampling was terminated at 15 seconds or when 10,000 droplets were sampled. Two subsamples were taken for each spray formulation and combined. Distributions were fit using MATLAB® R2010a distribution fitting tool to determine the count median diameter (CMD; μm) and the volume median diameter (VMD; μm) using the Hatch-C hoate conversion equations.

Wind speed, air temperature, wet-bulb depression, and relative humidity were measured with sensors positioned 2.5 m above the ground. Temp erature and relative humidity readings were also taken 10 m above the ground. Meteorological measurements were taken upwind of the spray site. Wind speed, wet bulb depression, temperature, and relative humidity at both 2.5 and 10 m above the ground were averaged over a 5 minute interval.

Using 1,067 data points from three years of sampling, a linear regression model was developed relating the natural logarithm of deposition (C) to wind speed (WS), temperature (T), relative humidity (RH), stability (SC), distance from the spray source (D), application rate (AR), flow rate (FR), density (DEN), count median diameter (C MD), and volume median diameter (VMD), as well as a number of terms which were the products of the aforementioned terms. The regression is depicted below

C = -3.71 + 0.008D - 1.15AR -0.005FR - 24.57DEN + 3.95CMD + 1.13VMD -0.014WS + 0.34T + 0.15RH + 1.44SC - 0.007(D * CMD) - 0.00002(D * WS) + 18.95 (DEN * CMD) - 0.007(DEN * WS) - 1.66(DEN * SC) - 0.16(CMD * T) - 0.064(CMD * RH) - 0.32 (CMD * SC)- 0.78(CMD * VMD)- 0.004(VMD * T) + 0.034(VMD * SC) + 0.001(WS * T) + 0.0001(WS * RH) + 0.0004(WS * SC) - 0.003(T * RH)

Figure C-2 shows the estimated prediction line for Aqua -Reslin for an application rate of 7.85 g/ha, a flow rate of 197 mL/min, a density of 0.996 g/mL, a CMD of 1.66 μm, a VMD of 20 μm, a wind speed of 316 cm/s, a temperature of 23oC, a relative humidity of 43%, and stability category of 2 (neutral). The selected model input s were the average for all variables measured during experiments for Aqua-Reslin. Table C-1 depicts the parameters used in the Schleier model for etofenprox.

### 23 Figure C-2. Example Depiction of Schleier 2012 Model Prediction for Aqua-Reslin

### 24 Table C-1. Input Parameters for Schleier 2012 ULV Model for Etofenprox