UNITEDSTATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON,D.C. 20460 a*,<€='S'4? # 

## a\ OFFICE OF PREVENTION. PESTICIDES AND TOXIC SUBSTANCES '4n @

# =I Ju

# ly3C!?~8f DPBarcode: D274 1 16 

# PC: oau/o/ REVISED LABELS AND 

### MITIGATION REVIEW 

### SUBJECT: EFED Review of Lorsban*-4E, Lock-On*, and Lorsban* 15G Label Changes 

### TO: Margaret Rice, Acting ChieflProduct Manager 52 Tom Myers, Chemical Review Manager Special Review and Reregistration Division (7508C) 

### FROM: William Rabert, Biologist Environmental Risk Branch 

### I11 Jim Lin, Environmental Engineer Environmental Fate and Effects ~igision (7507C) 

### THRU: Arnet Jones, Chief Environmental Risk Norm Birchfield Environmental Risk Branch 

### I Environmental Fate and Effects Division (7507C) At SRRD's request, EFED reviewed the proposed label changes to some chlorpyrifos labels proposed by Dow AgroSciences. The proposed labels reviewed include Lorsban*-4Et Lorsban* 15G,and Lock-On*. The label changes are an improvement with clarification of some use limitations not included onprevious chlorpyrifos labels and some risk reduction proposals such as: reductions in use rates, annual limitations on the number of applications, limits on lbs per acreper season, and most retreatment intervals set at 10 days. EFED's comments on the proposed label changes arepresented below in Attachment I. EFED's suggestion in the attachment for the language on the label concerning spray drift management reflects the latest draft of commentslconsensuscoming out of our inter-divisional meeting with Marcia Mulkey on the subject onJune 29, 2001. A table with a comparison of the old and the proposed labels is presented in Attachment 

### I1 SRRD also requested that EFED quantify the risks for some of the mitigation proposals made by Dow on their labels, especially those addressing risks from spray drift. Using the AgDRIFT Model, EFED assessed the level of risk mitigation achieved by the no-spray buffer zones proposed by Dow. EFED compared the risks posed by no buffer zone to the proposed no-spray buffer zone, and also assessed risks if there were no spray drift at all,just runoff. The assessment of risk mitigation also included whatever other modifications were proposed for thatuse. Five major crop scenarios were assessed for buffer zones mitigation. EFED's assessment suggests that risks would be reduced, except for the citrus air-blast scenario. Changes in citrus exposure levels are insignificant. However, even with mitigation there are still level of concern exceedences for all aquatic risk categories. The spray drift mitigation assessment is included as Attachment 111. Please note that the spray drift mitigation assessment is preliminary and should not be considered as official EFED policy. EFED's standard operating procedure for using AgDFUFT has not been finalized.Attachment 

### I. EFED has reviewed the proposed label changes for Lorsban*-4E, Lock-On*, and Lorsban* 15G. The registrant has proposed some modifications ofuse rates. Generally, they increased the minimum intervals between applications, deleted some application methods, substituted some safer application methods, reduced a few applicationrates, and put seasonal limitations on the number of applications and the poundage of chlorpyrifos to be applied seasonally. The label also added spray drift warnings and set no-spray buffer zones for ground, chemigation, orchard airblast, and aerial applications. The label format and information added to the new label are a definite improvement over the older labels. EFEDys review addresses the issues in the following order: Part 1.Recommended "spray drift" guidance for all agricultural labels employing spray applications. Part 2
. EFED comments on the proposed changes to Lorsban* -4E, Lock-On* and Lorsban* 15G labels. 

### Part 1.EFED has some comments on the label addressing spray drift: There appears to be a reversal of the wind speed limitations for aerial and ground applications. It is unclear why restrictions for ground applications are more stringent than for aerial applications. Some areas of concern have been found in the precautionary label. EFED recommends the following label language. 1. Substitute "no-spray buffer zone" where the term "buffer zone" appears. 

### 2. All references about wind direction with respect to the no-spray buffer zone need to be deleted. 3. EFED recommends adding the appropriate "no-spray buffer zone" requirement(s) to the "Restrictions" at the end of each crop. EFED recently reviewed the label guidance statements proposed by Dow on a new formulation, Lorsban* 75WG. A part of that label proposal was a section on no-spray buffer zones to reduce spray drift levels which would help protect fish and other aquatic organisms in aquatic habitats. EFED recommended a few modifications in the wording of the Lorsban* 75WG label. EFED recommends that the following spray drift management guidance be placed on the labels of Lorsban* 4E and Lock-On* which were provided for review.SPRAY 

### DRIFT 

### MANAGEMENT Do not allow spray drift to contact people or their living or working places, nontarget property onwhich structures are located, animals, recreation sites, areas where children play, nature preserves, wildlife refuges, parks, lakes, reservoirs, rivers, streams, non-irrigation canals, ponds, estuaries, wetlands, intertidal areas, forests, woodlands, pastures, rangeland, grasslands, nontarget crops, or ecologically significant sites. Avoiding spray drift at the application site is the responsibility of the applicator. The interaction of many 

### equipment-and-weather-related factors determine the potential for spray drift. The applicator is responsible for considering all these factors when making the decision to apply this product. Observe the following precautions when spraying Lorsban 75WG adjacent to permanent bodies of water such as rivers, natural ponds, lakes, streams, reservoirs, marshes, estuaries, and commercial fish ponds. The following treatment setbacks or no-spray zones must be utilized for all applications from the above listed aquatic areas with the following equipment:

Making applications when wind is blowing away from sensitive areas is the most effective way to reduce the potential for adverseeffects.

Application Method Ground Boom Chemigation Orchard Airblast Aerial (fixed wing orhelicopter)

The following mandatory spray drift 

### best management practices are required to reduce the likelihood of off-target drift movement from applications. Required Setback (No-spray Zone) 25 feet 25 feet 50feet 150feet



### Aerial Application: 1. Thedistance of the outer most nozzles ontheboom must not exceed 314 the length of the wingspan orrotor. 2. Nozzles must always point backward parallel with the air stream and never be pointed downwards more than 45 degrees. 3. Nozzles must produce a medium or coarser droplet size (255-340 microns volume median diameter), per ASAE Standard 572 under application conditions. Airspeed, pressure, and nozzle angle can all affect droplet size. See manufacturer's catalog or USDAINAAA Applicator's Guide for spray size quality ratings. 4. Applications must not be made at a height greater than 10feet above the top of the target plants unless a greater height is required for aircraft safety. Making applications at the lowest height that is safe reduces exposure of droplets to evaporation and wind.5. Do not apply product when wind speed exceeds 

### 10mph. 

### 6. Where states have more stringent regulations, they must be observed. The applicator should be familiar with and take into account the information covered in the Aerial Drift Reduction Advisory. Aerial Drift Reduction Advisory [This section is advisory in nature and does not supercede the mandatory label requirements.] INFORMATIONONDROPLET SIZE Themost effective way to reduce driftpotential is to apply large droplets. Thebest drift management strategy is to apply the largest droplets that provide sufficient coverage and control. Applying larger droplets reduces drift potential, but will not prevent adverseeffects from drift if applications are made improperly, orunder unfavorable environmental conditions (See Wind, Temperature and Humidity, and TemperatureInversions). CONTROLLING DROPLET SIZE 

### o Volume - Use high flow rate nozzles to apply the highest practical spray volume. Nozzles with higher rated flows produce larger droplets.
o Pressure - Do not exceed the nozzle manufacturer's recommended pressures. For many nozzle types lower pressure produces larger droplets. When higher flow rates are needed, use higher flow rate nozzles instead of increasing pressure. o Number of nozzles - Use the minimum number of nozzles that provide uniform coverage. 

### o Nozzle Orientation - Orienting nozzles sothat the spray is released parallel to the airstreamproduces larger droplets than other orientations and is the recommended practice. Significant deflection from horizontal will reduce droplet size and increase drift potential. o Nozzle Type - Use a nozzle type that is designed for the intended application. With most nozzle types, narrower spray angles produce larger droplets. Consider using lowdrift nozzles. Solid stream nozzles oriented straight back produce the largest droplets and the lowest drift. BOOM LENGTH For someuse patterns, reducing the effective boom length to less than 314 of the wingspan or rotor length may further reduce drift without reducing swath width.

### APPLICATION HEIGHT Applications should not be made at a height greater than 

### 10feet above the top of the target plants unless a greater height is required for aircraft safety. Making applications at the lowest height that is safe reduces exposure of droplets to evaporation and wind. 

### SWATH ADJUSTMENT When applications are made with a crosswind, the swath will be displaced downwind. Therefore, onthe up and downwind edges of the field, the applicator should compensate for this displacement by adjusting the path of the aircraft upwind. Swath adjustment distance should increase, with increasing drift potential (higher wind, smaller drops, etc.). 

### WIND Drift potential is lowest between winds speeds of 

### 2 - 

### 10mph. However, many factors, including droplet size and equipment type determine drift potential at any given speed. Application should be avoided below 2 mph due to variable wind direction and high inversion potential. NOTE: Local terrain can influence wind patterns. Every applicator should be familiar with local wind patterns and how they affect spray drift. 

### TEMPERATURE AND HUMIDITY When making applications in lowrelative humidity, set up equipment to produce larger droplets to compensate for evaporation. Droplet evaporation is most severe when conditions areboth hot and dry. 

### TEMPERATURE INVERSIONS Applications should not occur during a temperature inversion because drift potential is high. Temperature inversions restrict vertical air mixing, which causes small suspended droplets to remain in a concentrated cloud. This cloud canmove inunpredictable directions due to the light variable winds common during inversions. Temperature inversions arecharacterized by increasing temperatures with altitude and are common onnights with limited cloud cover and light to no wind. They begin to form asthe sun sets and often continue into the morning. Their presence canbe indicated by ground fog;however, if fog is not present, inversions can also be identified by the movement of smoke from a ground source or an aircraft smoke generator. Smokethat layers and moves laterally in a concentrated cloud (under low wind conditions) indicates aninversion, while smokethat moves upward and rapidly dissipates indicates good vertical air mixing. 

### SENSITIVEAREAS Thepesticide should only be applied when the potential for drift to adjacent sensitive areas (e.g. residential areas,bodies of water, known habitat for threatened orendangered species, nontarget crops) is minimal (e.g. when wind is blowing away fromthe sensitive areas).

### Ground Boom Application: The following mandatory spray drift 

### best management practices arerequired to reduce the likelihood of off-target drift movement from ground applications. 1. Choose only nozzles and pressures that produce a medium or coarse droplet size (255-400 microns volume median diameter), per ASAE Standard 572. See manufacturer's catalog or USDAINAAA Applicator's Guide for spray size quality ratings. 

### 2. Make applications with nozzle tips no more than 2 feet above the ground or crop canopy. Making applications at the lowest height reduces exposure of droplets to evaporation and wind. 3. Do not apply product when wind speed exceeds 10mph. 

### Orchard AirblastApplication: The following mandatory spray drift 

### best management practices are required to reduce the likelihood of off-target drift movement from airblast applications. 1. Nozzles must be directed so spray is not projected above the canopies. 2. Do not apply product when wind speed exceeds 10mph for aerial and ground applications. 3. Outward pointing nozzles must be shut off when turning corners at row ends. The applicator should take into account the following 

### best management practicesto reduce off-site spray drift. [This section is advisory and does not supercede mandatory label requirements.] 1. Number of nozzles, nozzle orientation and spray volume, air speed and wind direction are key factors in adjusting airblast spray delivery to match the height and density of the crop canopy. Airblast equipment should be adjusted to provide uniform coverage while minimizing the amount of spray movement over-the-top or completely through the crop canopy. High air volumes deliver spray more efficiently than air at high speed. Reducing forward travel speed decreases the air speed necessary to deliver the spray to the top of the cropcanopy. Use air guides along with the number and orientation of spray nozzles to achieve the desired spray coverage and directional control. 

### 2. The following steps should be taken to minimize drift and the amount of non-target spray: Orient nozzles and adjust air speedlvolumeldirection to minimize spray movement over-the-top and avoid forcing the spray completely through the crop canopy. Shut off spray delivery when passing gaps in crop canopy within rows. Spray the outside rows or orchards from in, directing the spray into the orchard and shutting off nozzles onthe side of the sprayer away from the orchard. When treating smaller trees, vines orbushes, shut off nozzles to minimize over-thetop spray movement.

### Part 11. EFEDComments onProposed Label Use Changes: SRRDhas indicated their desire that in no case, should the revised label include new uses or increase the use rates, number of applications, or the maximum poundage per acre per season for existing uses onthe Lorsban labels. In part, the label revisions are an effort to reduce risks to fish and wildlife with buffer zones around aquatic areas, reductions in use rates, number of applications and maximal seasonal use rates, as well as an increase in the minimum intervals for retreatment. EFED has reviewed the proposed label revisions for Lorsban* -4E, Lock-On*, and Lorsban* 15G. Theuse information fromthe old and new labels was entered into a table in Appendix I on a crop-by-cropbasis. Comparison of the labels included: maximum use rates, the number of applications3the minimum interval between applications, and the total poundage allowed per season. EFED found the new labels easier to understand and found them to be more complete, especially with respect to the minimum interval between applications and maximum seasonal poundage. The addition ofthe restriction limiting the use of other chlorpyrifosproducts has been noted for many crops. Someuse patterns have been changed which may reduce exposures to terrestrial wildlife. For example, the new Lorsban* 15G label replaced band treatments with T-band applications. While chlorpyrifos exposures have not been eliminated, the number of granules on the soil surface available to birds as grit are reduced. Several regional cropuses, such as cotton in AZ and CA, corn in FLand GA, and tobacco in NC, SC, and VA, with particularly high application rates have had their use rates sharply reduced. Seasonal limits have been reduced for several crops including: citrus orchard floors, corn, cotton, sugar beets, sunflowers, etc. All these changes are modifications in the direction of reducing risks to terrestrial and aquatic organisms. In some cases, missing use information should be added to the new labels for clarity. For example, the seasonal poundage limitations may not be obvious, if other chlorpyrifos formulations canbe used at a different use rates. Part 11. 

### A. EFED recommends the following modifications onthe new Lorsban* -4E label: Page 15. Alfalfa: Add the seasonal poundage limitation for chlorpyrifos. Page 16. Asparagus: Add the seasonal poundage limitation for chlorpyrifos. Page 17. Christmas trees: Add the seasonal poundage limitation for chlorpyrifos. Page 20. Corn: The following restrictions for feeding livestock appear to be inconsistent. Do not feed treated cornfodder to meat or dairy animals within35 

### days after last treatment. Do not allow livestock to graze in treated areas nor harvest treated corn silage as feed for meat ordairy animals within

## 14days after last treatment. Page 24-25. Cranberries: Add the seasonal poundage limitation for chlorpyrifos. Page 26. Onions (Dry Bulb): Add the seasonal poundage limitation for chlorpyrifos.Page 29. Soybeans: The old Lorsban*

### 4E has a minimum of 14 days between treatments. Please change the number back to 14days. Page 29-30. Strawberries: Add the seasonal poundage limitation for chlorpyrifos. Page 36. Peaches / nectarines: Theuse rate (430qtI100 gal.) is a misprint. The rate should be "3.0 qt/100 gal." Page 37. Cherries: Add the seasonal poundage limitation for chlorpyrifos use for trunk treatments. Page 37. Pecans: The use rate for ants on the pecan orchard floor was increased from 1to 2 lbs ai./Ato 2 to 4 Ibs ai./A. Since increases in use rates are not permitted, the use rate should remain at a maximum of 1to 2 lbs ai./A. Page 39. Brussel Sprouts: Add the seasonal poundage limitation for chlorpyrifos. Page 39. Wheat: Wheat was not previously listed on the Lorsban*-4E label. The no-spray buffer zone proposed for wheat is greater than those proposed for other chlorpyrifos uses (i.e.,30 feet for ground application and 300 feet for aerial application versus 25 and 150feet, respectively). The reason for the larger no-spray zone is that the prairie pothole region is an important waterfowl breeding area which is dependent on aquatic invertebrates to feed the young birds and needs more protection than other crop areas. Page 40. Wheat: Add the seasonal poundage limitation for chlorpyrifos. Part 11. 

### B. EFED comments on the proposed Lock-On* label changes. Page 

### 8. Wind speeds are inverted for ground and aerial spray applications. The "spray drift" guidance text cited in Part 

### I should also replace the section on the Lock-On* label. Page 9. Alfalfa: Under "Restrictions" the reference to "Do not make more than 4 applications per year 

### .. .,appears to be inconsistent with the changes cited onpage 1 1in the ChlorpyrifosRisk Mitigation memo by Jachetta et al.,Aug. 28, 2000. The old rate was 4 applications; 3 applications would be an improvement. Add the seasonal poundage limitation for chlorpyrifos on alfalfa. Part 

### 11. C. EFED comments on the proposed Lorsban* 15G label changes. Page 7-8. Corn: Pesticidal statement about ccsuppression of certain soil-borne pathogens that may result in physiological and agronomic advantages . .." should specify what specific soil-borne pathogens data exist. On the Lorsban labels references are made to pest species that are suppressed and in all cases but in this case, the pathogen(s) should specified and a applicationrate is specified. Thephrase "may result" is too imprecise and appears to reflect uncertainty. Such a claim does not appear onthe Lorsban*-4E label.Page 

### 8. There appears to be an omission ofuse information for the flea beetle. The flea beetle is listed as a pest for corn, but there is no indication what applicationmethod is appropriate and what use rate should be used to control it. Page 

### 9. There appears to be inconsistency in the "Restrictions" for the feeding of treated corn silage to livestock (i.e., 14 days or 

### 35 days after last treatment). Page 10. SorghumIMilo: The restrictions allow only one application at 

### 8oz. (1.2 oz. ai.)per 1,000feet of row. Please designate the maximum poundage per season. Page 12. Soybeans: Therestrictions allow one granular application at 

### 8oz. (1.2 oz. ai.)per 1,000feet of row and 2 foliar applications. Please designate the maximum poundage per season for soybeans. Page 13. Add the maximum poundage per season for all chlorpyrifos uses on sunflowers.Attachment 11. Comparison of use information on the old and the proposed labels. Lorsban*4E: Registered Crop Uses Alfalfa Asparagus Christmas trees Foliar Trunk Citrus Fruits Foliar Floor Corn Preplant Incorp. Preplant Cons. T-Band at Plant Foliar FL & GA Cotton CA & AZ Cranberries Figs (CA only) Grapes MintPreharvest Postharvest Onions Peanuts Preplant Postplant Sorghum Soybeans Lorsban*

### 4E: Old label (dated 09/27/00) Use (Ibs Old 0.25 - 0.5 0.5 - 1.0 1.O 1.O 3/100gal.

1.0 - 6.0 0.75-1.0
1.0 - 3.0 0.5 - 1.0 2.4 fl. oz. 0.25- 1.5 0.5 - 1.0 0.19- 1.0 0.5 - 1.0 1.5 2.0 2.0115 ft' 1.0- 2.0 1.1 fl. oz. 2.0 0.25- 1.O 0.5 - 1.0 Old label Rates ai/A) Proposed 0.25 - 0.5 0.5 - 1.0 1 .O 1 .O 31100gal.

1.0 - 6.0 0.75-1.0
1.0- 3.0 0.5 - 1.0 2.4 fl. oz. 0.25- 1.0 N/A 0.19- 1.0 0.5 - 1.O 1.5 2.0 2.0115 ft' 1.0 - 2.0 1.1fl. oz. 2.0 0.25- 1.0 0.5 - 1.0 (dated 09/27/00) versus New label Maximum of Old

4 llcutting 3

-
2 as needed 1 or or 3 11or 22 6 2 1 1 1 1 1 1 or

-

- versus No. Applications Proposed 4 l/cutting 3 3
2 3
1 or or 2 or 3 N/A

3 2 1 1 1 1 1 1 or 3 3 New label (08/15/00) Min.

interval Old

-

- 7-10

30 as needed

N/A NIA N/A

- as needed

-

- N/A N/A N/A N/A > 21

- 14 (08/15/00) Max. Limitation

Old ??? ? ???? ? ???

7.5 10 7.5

11 6 3 2 ???? ????
????

4
1.5 3 Retreatment (days) Proposed 10 10 7
30 10

10
10 10 NIA N/A N/A N/A > 21

10 10 (cont.) Seasonal (lbs ai/A) Proposed

???? ???? ????

7.5 3 3.O

N/A

3 3 2 ???? ????
????

4

1.5 3Strawberries Preplant

Foliar SugarBeets

Preplant band Foliar broadcast

Foliar band Sunflowers Preplant Foliar Sweet Potatoes Tobacco NC, SC, VA 2.0 1.O 0.5 0.25- 1.0 0.33- 1.0
1.0 - 2.0 0.5- 1.5 2.0 2.0 - 3.0 5.O Tree Fruits: Dormant: Apples, pears, plums, prunes, almonds (limiteduse areas in CA), peaches, nectarines 2.0 1.O 0.5 0.25- 1.0 0.33- 1.0
1.0- 2.0 0.5 - 1.0 2.0 2.0 - Fruit trees

(listed above)
Sour Cherries Dormant Trunk 1 2 4

3 1 2 1 1 1
0.25-0.51

100gal. min. 0.75 Ibs ai/A 0.25-0.51

100gal.
Tree Fruits and Tree Nuts: Foliar (Not on apples) 1 2 3

3

1 1 - 0.25-0.51

100gal. min. 0.75 Ibs ai/A 0.25- 0.51

100gal. min.0.75 Ibs ai1A
Almonds Cherries (Sour) Filberts Pecans

Walnuts NIA -

- - -
NIA 7 - 10 NIA NIA NIA
1

3 1 2or3

-

- 7 - 10 10- 14

- 2.0 ??? ? 1.5 - 2.0 0.5 - 2.0

2.0 Tree Fruits and Tree Nuts: Trunk Spray N/A 10 - 14

10

10

NIA NIA

-
1

1

-

10 10 10 10

10 2.0 1.0- 1.5 1.5- 2.0 0.25- 2.0

2.O 4
4

4.5

2 3

NIA

NIA

???? 6
???? 6 5

4



### Lorsban*

### 4E: Old label (dated 09/27/00) versus New label (08/15/00) (cont.) 14 4
3

3

2 2 -

4 4 4 4

4 3

5

2

???? ? ??? 3 10

N/A

3 3 3 3

2

???? Almonds Cherries (Sour) 3.01 100gal. 1.5- 3.01 100gal. 1.5 - 3.01 100gal. min. of 0.75 Ibs

ailA
????

3 2

2Nectarines1 Peaches Orchard Floors: Almonds, pecan and walnut 1.51 100gal.

Almonds Pecans Walnuts



### Lock-On*: Old label (dated 12/97)

### versus New label (08/15/00) ??? 4301 100gal.

2.0 - 4.0 1.0 - 2.0 2.0 - 4.0

Max. Seasonal Limitation (Ibs ailA) 1

2.0 - 4.0 2.0 - 4.0 2.0 - 4.0

Registered Crop Uses Old Min. Retreatment

Interval (days) Proposed Old Maximum No. of Applications 1

- ????

-

Proposed Old Use Rates (Ibs ai1A) Proposed Old NIA

2 2 2

Proposed NIA

-

-

- 1.51 100 gal.
10 10 10 ??? 4301 100gal.

8 ????

8 4 4 4Alfalfa AZ & CA

Cotton AZ & CA 0.75- 1.0

1.O 

### Lorsban* 15G: Registered Crop Uses Corn

Preplant:

Broadcast At plant:

T-band Band In-furrow Postplant:

Band Foliar:

Broadcast Citrus Floor Sorghum/Milo T-Band Band Onions At plant:

In-furrow Peanuts

At plant: Postplant Broadcast Soybeans

At plant:

T-Band Band Postplant Sugar Beets

At plant: T-Band Band Postplant 0.75- 1.0

1.0 4 l/cutting

Retreat 

### Old label (dated Use Rates (lbs Old
1.0 - 2.0 1.2oz. ai 1.2oz. ai 1.2oz ai. 0.525-1.2

oz. ai 0.75-0.98 1.O oz. ail1000

0.6 - 1.8 0.6 - 1.8

oz. ai/1000 0.555 oz.ai/lOOO 1.125-2.25 1.125-2.25

1.5- 2.0

Ib/A oz. ail1000 1.2 1.2 1.2 oz. ai/1000
- 0.675-1.35 0.975-1.35 4 or 3 (8/28/00 memo) 1 /cutting 3

ai/A) Proposed

- 1.2oz. ai - 1.2oz. ai

1.O oz. ail1000

0.6 - 1.2

oz. ai/1000 0.555 oz.ai/lOOO 1.125-2.25 1.125-2.25 - oz.ai/1000 1.2 - 1.2 oz. ai/1000 0.675-1.35 - 0.975-1.35 

### 01/06/00) versus New Maximum No. of Old

1 1 or or or 1 2 ????

1 or or 1 lor2 1 1 ????

1

1 ????

as needed
Applications Proposed

- 1 or - or 0.525-1.2

oz. ai 0.75-0.98 3 1
1 1 or2

1 1 - 1 or 2 withLorsbanf4E

1 or 3with Lorsban*- 4E 

### label (08/15/00) Min. Retreatment

Interval Old
N/A N/A N/A N/A N/A ??? as needed

N/A N/A N/A
???? ????

N/A N/A N/A N/A Max. Seasonal 10

10

(days) Proposed

N/A N/A N/A N/A

10 10 N/A
N/A

10

N/A

10

10 Limitation Old
2 or 2.4 oz.ai

2.4 oz.ai or1.95
10 ????

1 4 2.25 oz. ai/1000

or 2 lb/A
???? 1.2
2 Ib ai/A (Ibs ai/A) Proposed 3 1.2oz.ai

2.4 oz.ai or1.95
3 ???? 1.2oz.ai 1 4 2.25 oz. ai./1000 -

????
3 Ib ai/A ????

4

???? ???? 4 or 3 in memo
3Sunflowers A1 plant: T-Band Band Sweet Potato

Pre-plant

Broadcast Tobacco

Pre-plant

Broadcast Brassicacrops

At plant:

T-Band Radishes

At plant:

In furrow oz. ail1000

- 1.2oz
2.0
2.0 - 3.0 oz. ail1000 0.69- 1.38

oz. ail1000 0.495 oz. ai/1000 1.202. -
2.0
2.0 oz. ail1000 0.69- 1.38

oz. ail1000 0.495 1

1
1
1

1 1 or 3 with 4E spray 1
1
1

1 N/A

N/A
NlA
N/A

N/A 10

N/A
N/A
N/A

NlA ????

????
3.0
1.125 40" row

2.25 22" row

2.745 ????

????
2.0
1.125 40" row

2.25 22" row 2.745Attachment 111. EvaluationofNo-spray Buffer Zone Mitigation Proposals. Theregistrant, Dow-Agrosciences hasproposed using the followingno-spray buffer zones to reduce risks to aquatic organismsposed by chlorpyrifosspray applications.



### Background

Application Method Ground Boom Chemigation Orchard Airblast Aerial (fixed-wing orhelicopter)
SRRD asked EFED to assess the potential mitigation of aquatic risks that could result from nospray buffer zones adjacent to aquatic areas. Theproceduresused in this assessment shouldbe considered preliminary and are forthe purpose ofthis exerciseonly. Thisassessment doesnot reflect EFEDpermanent policy orthe input parameter guidance document. Required Setback (No-spray Zone) 25feet 25feet 50feet 

### 150feet

Several factors should be kept in mind concerning the reassessment of chlorpyrifos risks with the no-spray buffer zones proposed by the registrant:

- Only five scenarios were evaluated for this exercise, and those were evaluated using the PRZM-EXAMS model. Most of the original risk scenarios in the Chlorpyrifos RED were assessed using the screening-level GENEEC model. The GENEEC model in its current form cannot calculate the potential reduction in exposure gained from no-spray zones.

- Where the PRZM-EXAMS model was used in the original assessment, the spray drift factors (expressed as a fraction of the application rate) were 1% for ground boom applications and 5%for airblast and aerial applications. These are median values taken from open literature papers. In this analysis the AgDRIFT model was used, which assumes deposition of the 

### 90th percentile drift value from the model. Drift loadings to the water body were evaluated with and without the no-spray buffer. Because the drift fractions in the original RED differ from those employed in AgDRIFT, it would not be appropriate to consider the original default spray drift values in this comparison. Using AgDRIFT for the no-spray zone and the standard drift loading values fromtheoriginal RED (and EFED's input parameter guidance) has theeffect of comparing results calculated atdifferentpercentiles.

- This procedure considers only the reduction in spray drift to the body of water. The buffer's possible impact on reducing runoff is not considered because PRZM-EXAMS does not have this capability. Theproblem of runoff is more complicated. Forexample, if runoff is channelized, the buffer zone would probably have little effect on the pesticide levels transported to the aquatic habitat. 

### Risk Assessment ComparisonsofNo Buffer, Buffers, and No Drift Scenarios: Based onmajor chlorpyrifos cropuses and differences in spray application methods, five use scenarios were selected to assess the level of mitigation obtained using the proposed no-spray buffer zones. The scenarios include the major spray application methods (i.e.,ground, airblast and aerial spray applications) and the proposed changes in use rates. In two scenarios (i.e.cornpre-plant and citrus), no use modifications were proposed in the use rates or manner of application, exceptthe no-spray drift zones. Inthree scenarios, the registrant has proposed reductions in the use rate (i.e.,aerial corn and tobacco) orreductions in the number of applications (i.e.,cotton). Theseproposed reductions have been included in the following risk mitigation assessment. Chemical properties and fate parameters for chlorpyrifosremain the same as those used in the 

### RED. Tobetter understand the sources of risk and risk mitigation, the PRZM-EXAMS model was used to recalculate all aquatic EECs including no buffer, the proposed no-spray buffer zone and assuming that there is no spray drift at all (i.e.,only runoff into the aquatic habitat). Toestimate the spray drift amount,EFEDused the PRZM input parameter, DRFT,to define the off-target spray drift to the standard fm pond. Forthe mitigation investigationsrelated to buffer restriction, EFEDused theAgDRTFTmodel (version 1.07) topredict the differentDRFT values for differentbuffer restrictions. For purposes ofcomparison,tier 1 ofthe AgDRIFT model was used. The general parameters fortier 1 assessment aretabulated below. When using theAgDRIFT model,theuser isprompted to choosetier (I, 11,or 111)and applicationmethod (aerial: ground: or orchard airblast). Once thetier and applicationmethod are chosen, theuser then proceeds to toolbox function and chooses aquatic assessment to obtain the drift value. Forthe evaluationof bufferrestriction, theblank for "Distance to water body from edge offield" needs to be entered. A "0" indicatesnobuffer restriction, and a numerical value (e.g., 50 ft)indicates thebuffer restriction. Thedrift value, expressed asfraction ofapplied, isused asthe "DRFT" parameter in the PRZM fordrift loading to the EXAMS' standard farm pond. 

### GENERAL PARAMETERS FOR TIER 1ASSESSMENT Aerial Aircraft Description/ Operation Type Air TractorAT-401 Weight ofAircraft 26683N (5998 Ib) Wing Semispan 7.48m (24.5 ft)Flight Speed 53.6m/s (120mph) Release Height 3.05 m (10ft) Nozzle Setup Number 42 Vertical Offset -0.35m (-14in) Horizontal Offset -0.25m (-10in) Boom Span *5.7 m (3~18.7 ft) Spacing (even) 0.28m (11 in) Meteorology Wind Speed 

### @2 m (6.28ft) 4.47m/s (10mph) Wind Direction Perpendicular to Flight Path Surface Roughness 0.0075

### m (0.005m BCPC) Stability Neutral Relative Humidity 50% Temperature 30deg C (86degF) Test Substance 1Application Specific Gravity 1.O Nominal Application Rate 100ngIcm2 (0.25lblac) Swath Width 18.29m (60 ft) Nonvolatile Fraction 0.03 Number ofFlight Lines 2 0 CURVE SPECIFIC PARAMETERS Very Fine1 Fine1 Medium/ Coarse1 Parameter Fine Medium Coarse Very Coarse Swath Displacement 1 Swath % Swath 0 0 DvO.l 54mm 94mm 164mm 225 mm VMD (DvO.5) 119mm 216mm 353mm 463 mm Dv0.9 204 mm 369mm 598mm 789mm Fraction < 141mm 0.57 0.20 0.06 0.03 The finelmediumdroplet size category (the default value) was used in the aerial assessment. Ground Boom There are two ground sprayer application scenarios: low boom and high boom. The high boom scenario was used for this assessment.Orchard There are three orchard airblast application scenarios: Normal (Stone & Pome Fruit, Vineyard), Dense (Citrus, Tall Trees) and Sparse (Young, Dormant). The curve for Dense canopies was used for this assessment. 

### Mitigation Summary ofBuffer Zones (based on AgDRIFT results to PRZMIEXAMS) The drift reduction calculations based on AgDRIFT model for ground boom, orchard airblast, and aerial spray are tabulated below:

Three scenarios were compared for each case: (1) old use pattern, (2) new proposed pattern with buffer restrictions, and 

### (3) new proposed patterns assuming no spray drift at all. EECs are expressed in ug1L. The results are shown below. 

### Off-Target SprayDrift Estimations Based on AgDRIFT (version 1.07)



### Case #1: Application Method Ground Boom Aerial Spray Orchard Airblast



### Iowa Corn

### - 1 ground spray @

### 3 lb aiIA, 2"incorporation - No buffer restrictions PROB PEAK 96HOUR 21 DAY 60DAY 90 DAY YEARLY 1/10 10.096 8.038 4.279 2.255 1.692 .590 

### Iowa Corn

### - 1 ground spray @

### 3 Ib ai/A, 2"incorporation - 25-ft buffer restrictions PROB PEAK 96HOUR 21 DAY 60DAY 90DAY YEARLY 1/10 5.694 4.770 2.634 1.488 1.128 .418 

### Iowa Corn

### - 1ground spray @

### 3 

### Ib ai/A, 2"incorporation - No off-target sDrav drift PROB PEAK 96HOUR 21 DAY 60DAY 90DAY YEARLY 1/10 2.550 2.009 1.153 .580 ,462 .I98 Drift Amount (No Buffer) 6.05%

15% 1.85%



### Case #2: Drift Amount (Buffer Restriction) 3.37% (25-ft) 5.27% (150-ft) 0.89%(50-ft)

### Iowa Corn

### - 3 aerial sprays @ 

### 1.5lb ai/A, 14-dayinterval - No buffer restrictions PROB PEAK 96 HOUR 21 DAY 60 DAY 

### 90DAY YEARLY 1/10 17.041 13.778 9.285 6.600 5.052 1.717 

### Iowa Corn - 

### 3 aerial sprays @ 

### 1.0lb ai/A, 10-dayinterval - 150-ftbuffer restrictions PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 1/10 5.091 4.261 2.939 1.824 1.406 .496 

### Iowa Corn 

### - 3 aerial sprays @ 

### 1.0 lb ai/A, 10-dayinterval - No off-target spray drift PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 1/10 1.690 1.330 .818 .460 .385 .I51


### Case#3: Florida Citrus

### - 2 

### airblast applications @3.5 lb ai/A, with 30-day interval - No buffer restrictions PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 1/10 20.808 16.691 9.612 6.596 5.241 2.086 

### Florida Citrus 

### - 2 airblast applications @3.5 lb ai/A, with 30-day interval - 50-ftbuffer restrictions PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 1/10 20.571 16.233 9.321 6.451 5.041 1.938 

### Florida Citrus 

### - 2 airblast applications 

### @3.5 lb ai/A, with 30-day interval - No off-target sDrav drift PROB PEAK 96 HOUR 21 DAY 60 DAY 90DAY YEARLY 1/10 20.046 15.661 9.119 6.266 4.924 1.799



### Case#4: hlississippi Cotton 

### - 6 aerial sprays @ 

### 1.0 lb ai/A, 3-day interval - No buffer restrictions PROB PEAK 96 HOUR 21 DAY 60DAY 90 DAY YEARLY 1/10 26.433 22.213 16.837 9.383 7.245 2.608 

### MississippiCotton 

### - 3 aerial sprays @ 

### 1.0 lb ai/A, 10-dayinterval 

### - 150-ftbuffer restrictions PROB PEAK 96 HOUR 21 DAY 60DAY 90 DAY YEARLY 1/10 5.348 4.240 3.063 1.961 1.619 .652 

### hlississippi Cotton 

### - 3 aerial sprays @ 

### 1.0 lb ai/A, 10-dayinterval 

### - No off-target sprav drift PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 1/10 2.640 2.113 1.283 .800 .659 .316

### Case #5: North Carolina Tobacco

### - 1 

### pre-plant ground spray @ 

### 5.0lb ai/A, 4"

### incorporation

### -No buffer PROB PEAK 96 HOUR 21 DAY 60 DAY 90DAY YEARLY 1/10 40.371 31.720 16.393 9.076 6.916 2.197 

### North Carolina Tobacco - 1

### pre-plantground spray @

### 2.0Ib ai/A, 2"incorporation -Lft buffer PROB PEAK 96 HOUR 21 DAY 60 DAY 90DAY YEARLY 1/10 14.048 11.006 5.475 3.115 2.386 .758 

### North Carolina Tobacco

### - 1 

### pre-plant ground spray @ 

### 2.0 Ib ai/A, 2"incorporation

### -No 

## driftPROB PEAK 96 HOUR 21 DAY 60DAY 90 DAY YEARLY 1/10 11.106 8.697 4.376 2.521 1.935 .607

### Scenario # 

### 1. Pre-plant corn risk scenario with the maximum proposed use rate: Risk Quotients for Corn in Pottawattamie Co., Iowa (Pre-plant Ground Spray; 1 Application at 3 Ibs ai/A;2-inch Soil Incorporation) (AquaticEEC'sBased onPRZM3.12-EXAMS Model) Species

Freshwater Fish Acute LC,, Fish Reproduction NOAEC Aquatic Invertebrate Acute LC,, Exposures (pg/L) No Buffer I Buffer I No Drift
10.1 1 5.7 I 2.5S1 10.1 1 5.7 1 2.5~~

Freshwater Invert. Reproduction NOAEC 10.1 1 5.7 1 2.55 

# I 11 Estuarine lnverlebrate Acute LC,,, 

### I 10.1 / 5.7 1 2.55 

### 1 0.035 

### 1 290 1110 1 73 I I

Toxicity

(pg1L) 1.8 0.57

10.1 1 5.7 1 2.55 4.2 / 2.6 / 1.15
Estuarine Fish Reproduction NOAEC 

# II Estuarine Invert. Reproduction NOAEC 

# I 10.1 1 5.7 / 2.55 > 2200 I > 1200 / > 550 4.2 1 2.6 1 1.15 

# I < 0'W46 

# 1 > 910 1 > 570 1 > 250 Risk Quotients No Buffer I Buffer I No Drift
5.6 1 3.2 I 1.4 18 1 10 1 4.5 0.10

Estuarine Fish Acute LCn 100 1 57 1 26 0.04

10.1 1 5.7 1 2.55 4.2 1 2.6 1 1.15



### ' 21-Day EECs in 2-meter deeppond or estuarine water 250 1 140 1 64 100 1 65 1 29 I I I 10.1 1 5.7 1 2.55 

### 1 0.96

Estuarine Algae EC,,


### Risk Summary for Maximum Preplant Spray to Corn: Chlorpyrifosground-sprayed as a preplant application at 3 Ibs ai/A and soil incorporated to 2 inches yields risk quotients which 

### exceed both acute (RQ

## >0.5) 

### and chronic (RQ

## > 1) levels of concern for all aquatic animal groups, except algae. Omitting risks to algae, 

### the lowest risk quotient posed by chlorpyrifos use on pre-plant corn is 1.4

### for acute freshwaterfish with no spray drift. From the aboverisk quotients, it is apparent that runoff alone from corn fields treated with 

### 3 Ibs 11 1 5.9 1 2.7 0.28

ai./A poses both acute and chronicrisks to aquatic organisms in all of the above groupings. In this ground spray application scenario, the 25-foot no-spray buffer zone reduces the EECs and risks by 44 percent. However, the risk quotients for the no-drift scenarioclearly show that there is no level of reduction in spray drift, which will totally mitigate chlorpyrifosrisks to aquatic animals. The no-spray buffer is a clear improvement over current application methods, but the data also show that a no-spray buffer zone alone can not eliminate acute orchronic risks to 36 1 20 1 9.1 15 1 9.3 1 4.1

I Peak EECs in ?-meter deeppond or estuarine water 10.1 / 5.7 1 2.55

sensitive aquatic animals. 140 0.07 1 0.041 1 0.0082Scenario# 2. Foliar corn risk scenario with three maximum aerial applications; proposed use modifications include a rate reduction from 1.5to 1Ibs ai./A and a 10-dayretreatment interval versus a previous 14-dayinterval. Risk Quotients for Corn in Pottawattamie Co., Iowa (Foliar, Aerial Spray; 3 Applications at 1.5 Ibs ai./A reduced to 1Ib ai/A) (Aquatic EEC's Based on PRZM3.12-EXAMS Model) Exposures (pglL) Toxicity Risk Quotients No Buffer IBuffer I No Drift

# I (pg/L) 

# 1 No Buffer I Buffer I No Drift
Freshwater Fish Acute LC,, Fish Reproduction NOAEC Aquatic Invertebrate Acute LC,, Freshwater Invert. Reproduction NOAEC 17.1 1 5.1 1 1.69' 17.1 1 5.1 1 1.69'

Estuarine Fish Acute LC,, Estuarine Fish Reproduction NOAEC Estuarine Invertebrate Acute LC,, Estuarine Invert. Re~roduction NOAEC

I Peak EECs in 2-meter deeppond or estuarine water

21-Day EECs in 2-meter deeppond orestuarine water 17.1 15.1 1 1.69 17.1 15.1 1 1.69

Estuarine Algae EC,,
Risk Summary for 

### 3Aerial, Foliar Spray Applicationsto Corn atthe Maximum Use Rate: 1.8 0.57

17.1 15.1 1 1.69 17.1 15.1 1 1.69 9.3 I 2.9 I 0.82 17.1 15.1 11.69 17.1 1 5.1 1 1.69

Chlorpyrifos applied asthree aerially, foliar spray applications at 1.5 and 

### 1Ib ai/Ayields risk quotients which exceed both the acute (RQ

# >0.5) and chronic (RQ

# > 1)levelsof concern for all aquatic animal groups, except algae. Omitting the risk quotients for algae, the lowestrisk quotient posed by three aerial applications on corn is 0.94 for acute freshwater fish, which assumes no spray drift at all. From the above risk quotients, it is apparent that runoff alone from corn fields aerially sprayed three times poses both acute and chronic risks to aquatic organisms in all of the above groupings. In this aerial spray scenario, the 150-foot no-spray buffer zone reduced the EECs and risks by 70percent. However, the risk quotients for the no-drift scenarioclearly 9.5 1 2.8 I 0.94 30 1 8.9 1 3.0 0.10 0.04

17.1 15.1 11.69 170 1 51 1 17 430 1 130 1 42 0.96 0.28 0.035 <0.0046 140 0.12 I 0.036 I 0.012 18 1 5.3 I 1.8 61 118 1 6.0 33 1 10 I 2.9 490 1 150 1 48 >3700 1>1100/>370show that the use of no-spray buffer zones can not totally mitigate chlorpyrifos risks to aquatic animals. About 10percent onthe exposure from the application without buffer zones occurs as runoff. The no-spray buffer is a clear improvement over current application methods, but the data also show that a no-spray buffer zone alone can not eliminate acute orchronic risks to sensitive aquatic animals. Scenario # 3. Two foliar airblast applications to Florida citruswith 30-day retreatment intervals (no changes in use rate, number of applications, or retreatment interval. Risk Quotients for Citrus in Osceola Co., Florida (Foliar, Airblast Spray; 2 Applications at 3.5 Ibs ai./A; 30-day Interval) (AquaticEEC's Based on PRZM3.12-EXAMS Model)


# 11 Aquatic Invertebrate Acute LC, 20.8 1 20.6 120.0 

## I 0.10 210 I 210 I 200 I I I Species

Freshwater Fish Acute LC,, Fish Reproduction NOAEC Exposures (pg/L) No Buffer I Buffer INo Drift
20.8 1 20.6 I20.0' 20.8 1 20.6 I20.0'
Freshwater Invert. Reproduction NOAEC Estuarine Fish Acute LC,, Toxicity (pglL)
1.8 0.57

20.8 1 20.6 120.0

9.62 I 9.32 I 9.12
Estuarine Fish Reproduction NOAEC 

## 11 Estuarine Invert. Reproduction NOAEC 

## 1 20.8 1 20.6 120.0 

## 1 <0.0046 

## 1 > 4500 1 >4500 1>4300 Risk Quotients No Buffer I Buffer I No Drift
12 1 11 I 11 36 I 36 1 35

I I I 20.8 1 20.6 120.0

Estuarine Invertebrate Acute LC, 0.04

20.8 1 20.6 120.0

9.62 1 9.32 1 9.12



### ' Peak EECs in 2-meter deep pond or estuarine water 

## ' 21-Day EECs in 2-meter deep pond or estuarine water 520 I 520 I 500 240 1230 I 230 0.96

20.8 1 20.6 120.0
Estuarine Algae EC,,
Risk Summary for 2 Foliar Air-blast Spray Applications to Citrus at Maximum Use Rate: 22 122 I 21 0.28

20.8 1 20.6 I 20.0 

# 1 140 0.151 0.151 0.14

Chlorpyrifos applied as two foliar air-blast spray applications at 3.5 Ibs ailA yields risk quotients which exceed both the acute (RQ

# >0.5) and chronic (RQ

## > 1)levels of concern for all aquatic animal groups, except algae. Omitting the risk quotients for algae, the lowest risk quotient posed by the foliar air-blast spray applications on Florida citrus is 

### 11for acute 74 174 1 71 60 111 1 4.6 0.035 590 I 590 I 570

### freshwater fish, which assumes no spray driftat all. From the above risk quotients, it is apparent that runoff alone from air-blast spray applicationsto citrus orchards poses both acute and chronic risks to aquatic organisms in all of the above groupings. In this aerial spray scenario, the 50-foot no-spray buffer zone only slightly reduced the EECs and risks by 1percent. The risk quotients for the no-drift scenario clearly show that the use of no-spray buffer zones can not totally mitigate chlorpyrifosrisks to aquatic animals. About 

### 96 percent of the exposure from the application without buffer zones occurs as runoff. The no-spray buffer for air-blast applications of citrus trees is not much improvement over current application methods. Foliar interceptionby the trees in the orchard reduces spray drift to a very minimum. Runoff alone from the orchard poses nearly all the risk for both acute or chronic risks to sensitive aquatic animals.

### Scenario # 4. 

### Six aerial spray applications toMississippi cotton; with proposal to reduce use to three aerial applications and 10-dayretreatment intervals. Risk Quotients for Cotton in Jackson Co., Mississippi (Foliar, Aerial Spray; 

### 6 versus 

### 3Applications at 1

### lb ai./A) (AquaticEEC's Based on PRZM3.12-EXAMS Model) Species Exposures (pg/L) No Buffer I Buffer I No Drift 

## 11 Fish Reproduction NOAEC 

## 1 26.4 15.35 1 2.64' 

## 1 0.57 

## 1 46 I 9.4 I 4.6

Freshwater Fish Acute LC,, Toxicity (pglL) Risk Quotients No Buffer I Buffer I No Drift

I I I 26.4 15.35 1 2.64'
Aquatic Invertebrate Acute LC,, Freshwater Invert. Reproduction NOAEC 1.8

26.4 15.35 I 2.64

Estuarine Fish Acute LC,, Estuarine Fish Reproduction NOAEC 

# 11 Estuarine Invert. Reproduction NOAEC 

# 1 26.4 15.35 I 2.64 

# 1 <0.0046 

# 1 > 5700 I > 12001>570 15 1 3.0 1 1.5

26.4 15.35 I 2.64 16.8 13.06 I 1.28

Estuarine Invertebrate Acute LC,, 26.4 / 5.35 I 2.64 0.10

26.4 15.35 I 2.64 26.4 15.35 I 2.64

I Peak EECs in 2-meter deep pond or estuarine water

21-Day EECs in 2-meter deep pond or estuarine water 260 I 54 I 26 0.04

I I 0.035
Estuarine Algae EC,,


### Risk Summary for Aerial, Foliar SprayApplicationsto Cotton at the Maximum Use Rate: 660 I 130 I 66 420 I 76 1 32 0.96 0.28 754 I 153 I 75

Chlorpyrifos applied as six and reduced to three aerial, foliar spray applications at 

### 1.0 lbai/A yields risk quotientswhich exceed both the acute (RQ

# >0.5) and chronic (RQ> 1)

### levels of concern for all aquatic animal groups, except algae. Omitting the risk quotients for algae, 

### the lowest risk quotient posed by three aerial applications on cotton is 1.5 for acute freshwater fish, which assumes no spray drift at all. From the above risk quotients, it is apparent that runoff alone from cotton fields aerially sprayed three times poses both acute and chronic risks to aquatic organisms in all of the above groupings. In this aerial spray scenario, the 50-foot no-spray buffer zone reduced the EECs and risks by 80percent. However, the risk quotients for the no-drift scenario clearly show that the use of no-spray buffer zones can not totally mitigate chlorpyrifos risks to aquatic animals. About 10percent of the exposure from the application without buffer zones occurs as runoff. The no-spray buffer is a clear improvement over current application methods, but the data also show that a no-spray buffer zone alone can not eliminate acute or chronic 28 I 5.6 I 2.8 94 1 11 I 9.4

26.4 15.35 I 2.64 140 0.19I 0.038 I 0.019risks to sensitive aquatic animals. Scenario # 5. OnePre-plant Ground Application toNorth Carolina Tobacco; with proposal to reduce use rateto 

### 2 Ibs ai./A from 5 Ibs ai./A and 

### 2" soil incorporation versus 4". Risk Quotients forTobacco in Wake Co., North Carolina (Pre-plant, Ground Spray; 5Ibs ai./A & 4" incorportation versus 2 Ibs ai./A & 2" incorp.) (AquaticEECtsBased on PRZM3.12-EXAMS Model) Species 

# 11 Freshwater Fish Acute LC, 40.4 I14.0 1 11.1' 1.8 2.2 1 7.8 1 6.2 Exposures (pg/L) No Buffer I Buffer I No Drift Toxicity (j~glL)

Fish Reproduction NOAEC Risk Quotients No Buffer IBuffer 1No Drift

Aquatic Invertebrate Acute LC,, 

# 11 Es~uarine Fish Acute LC, 40.4 1 14.0 1 11.1 

## 1 0.96 42 1 15 I 12 I I I 40.4 1 14.0 1 11.1' 16.4 15.48 I 4.38' Freshwater Invert. Reproduction NOAEC 

## 11 Estuarine Fish Reproduction NOAEC 

## 1 40.4 1 14.0 1 11.1 

## 1 0.28 

## 1 140 1 18 1 40 I I 1 40.4 1 14.0 1 11.1 0.57

40.4 1 14.0 1 11.1 16.4 15.48 1 4.38



## I Estuarine Algae EC,, 40.4 114.0 1 11.1 

### 1 140 

## I 0.29 1 0.10 1 0.079 I Peak EECs in 2-meter deer, pond or estuarine water 71 I 25 I 19 29 1 9.6 1 7.7 0.10

Estuarine Invertebrate Acute LC,, Estuarine Invert. Reproduction NOAEC

. . 

### ' 21-Day EECs in 2-meter deep pond orestuarine water 400 1140 I 110 0.04

Risk Summary for 1Pre-plant Ground Spray Application to Tobacco atMaximum Use Rate: 1000 1350 1180 410 1 140 1 110

40.4 I14.0 I 11.1 40.4 1 14.0 1 11.1 164 1548 1 418

Chlorpyrifos applied as a single pre-plant ground spray application at 5 Ibs ai/A with 

### 4" soil incorporation reduced to 

### 2 lbs ai/A with 

### 2" soilincorporation yields risk quotients which exceed both the acute (RQ

### 2 0.5) and chronic (RQ

# > 1)levels of concern for all aquatic animal groups, except algae. Omitting the risk quotients for algae, the lowest risk quotient posed by the pre-plant ground spray application on tobacco is 

### 6.2 for acutefreshwater fish, which assumes no spray drift at all. From the above risk quotients, it is apparent that runoff alone from tobacco fields ground sprayed poses both acute and chronic risks to aquatic organisms in all of the above groupings. In this aerial spray scenario, the 25-foot no-spray buffer zone reduced the EECs and risks by 

### 65percent. However, the risk quotients for the no-drift scenario 0.035 <0.0046 1200 1400 I 320 > 8800 I>3000 I >2400 36~ 1~1x-m ~,ssnclearly show that the use of no-spray buffer zones can not totally mitigate chlorpyrifos risks to aquatic animals. About 27 percent of the exposure fromthe application without buffer zones occurs as runoff. The no-spray buffer is a clear improvement over current application methods, but the data also show that a no-spray buffer zone alone can not eliminate acute or chronic risks to sensitive aquatic animals. Conclusions: Theno-spray zonesproposed by DowAgroScienceseach reduce the risks to aquatic animals compared to the currentuse methods. However, none of thebuffer zonestotally mitigate the risksto aquatic animals. Theno-spray drift assessment indicatesthat spray drift restrictions alonecan not totally mitigaterisks for even one aquatic group. According to the PRZM-EXAMS Model, the EECs fromrunoff ofchlorpyrifos fromtreated fields, alone, are sufficiently high topose risksto all aquatic animal categories: both acute and chronic.