UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

a*,<€=' S'4? 

# a\ OFFICE OF 

PREVENTION. PESTICIDES 

AND TOXIC SUBSTANCES 

@ '4n =I 

Ju ly3C!?~8f DP Barcode: 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 on previous chlorpyrifos labels and some risk reduction 

proposals such as: reductions in use rates, annual limitations on the number of applications, 

limits on lbs per acre per season, and most retreatment intervals set at 10 days. EFED's 

comments on the proposed label changes are presented 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 commentslconsensus coming out of our inter-divisional meeting with 

Marcia Mulkey on the subject on June 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 that 

Text Searchable File
use. 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 of use rates. Generally, they increased 

the minimum intervals between applications, deleted some application methods, substituted 

some safer application methods, reduced a few application rates, 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 

on which 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 adverse effects. 

Application Method 

Ground Boom 

Chemigation 

Orchard Airblast 

Aerial (fixed wing or helicopter) 

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 

50 feet 

150 feet 

Aerial Application: 

1. The distance of the outer most nozzles on the boom must not exceed 314 the length of the 

wingspan or rotor. 

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 10 feet 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 10 mph. 

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.] 

INFORMATION ON DROPLET SIZE 

The most effective way to reduce drift potential is to apply large droplets. The best 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 adverse effects 

from drift if applications are made improperly, or under unfavorable environmental conditions 

(See Wind, Temperature and Humidity, and Temperature Inversions). 

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 so that the spray is released parallel to the 

airstream produces 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 some use 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 10 feet 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, on the 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 - 10 mph. 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 low relative humidity, set up equipment to produce larger droplets 

to compensate for evaporation. Droplet evaporation is most severe when conditions are both 

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 can move in unpredictable directions due to the 

light variable winds common during inversions. Temperature inversions are characterized by 

increasing temperatures with altitude and are common on nights with limited cloud cover and 

light to no wind. They begin to form as the sun sets and often continue into the morning. 

Their presence can be 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. Smoke that layers and moves laterally in a concentrated cloud (under low wind 

conditions) indicates an inversion, while smoke that moves upward and rapidly dissipates 

indicates good vertical air mixing. 

SENSITIVE AREAS 

The pesticide should only be applied when the potential for drift to adjacent sensitive areas (e.g. 

residential areas, bodies of water, known habitat for threatened or endangered species, nontarget crops) is minimal (e.g. when wind is blowing away from the sensitive areas). 
Ground Boom Application: 

The following mandatory spray drift best management practices are required 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 10 mph. 

Orchard Airblast Application: 

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 10 mph 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 practices to 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 crop canopy. 

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 on the side of the sprayer away from the orchard. 

When treating smaller trees, vines or bushes, shut off nozzles to minimize over-thetop spray movement. 
Part 11. EFED Comments on Proposed Label Use Changes: 

SRRD has 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 on the 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. The use information from the old and new labels was entered into a table in Appendix I on 

a crop-by-crop basis. Comparison of the labels included: maximum use rates, the number of 

applications3 the 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 of the restriction limiting the use of other chlorpyrifos products has 

been noted for many crops. Some use 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 crop uses, 

such as cotton in AZ and CA, corn in FL and 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 can be used at a different use rates. 

Part 11. A. EFED recommends the following modifications on the 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 corn fodder 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 or dairy animals within 14 days 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 14 days. 

Page 29-30. Strawberries: Add the seasonal poundage limitation for chlorpyrifos. 

Page 36. Peaches / nectarines: The use rate (430 qtI100 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 1 to 2 lbs 

ai./A to 2 to 4 Ibs ai./A. Since increases in use rates are not permitted, the use rate 

should remain at a maximum of 1 to 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 150 feet, 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 on page 1 1 in the 

Chlorpyrifos Risk 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 application rate is specified. The phrase "may result" is too imprecise 

and appears to reflect uncertainty. Such a claim does not appear on the Lorsban*-4E 

label. 
Page 8. There appears to be an omission of use information for the flea beetle. The flea beetle 

is listed as a pest for corn, but there is no indication what application method 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 8 oz. (1.2 oz. ai.) per 

1,000 feet of row. Please designate the maximum poundage per season. 

Page 12. Soybeans: The restrictions allow one granular application at 8 oz. (1.2 oz. ai.) per 

1,000 feet 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 

Mint 

Preharvest 

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 

1.1 fl. 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 

11 or 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 

3 
Strawberries 

Preplant 

Foliar 

Sugar Beets 

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 (limited use 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 

100 gal. 

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 

100 gal. 

min. 0.75 

Ibs ai/A 

0.25- 0.51 

100gal. 

min.0.75 

Ibs ai1A 

Almonds 

Cherries (Sour) 

Filberts 

Pecans 

Walnuts 

NI A 

- 

- 

- 

- 

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 

100 gal. 

1.5 - 3.01 

100gal. 

1.5 - 3.01 

100gal. 

min. of 

0.75 Ibs 

ail A 

? ? ? ? 

3 

2 

2 
Nectarines1 

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) 

Old Proposed 

Maximum No. 

of Applications 

1 

- 

???? 

- 

Old Proposed 

Use Rates 

(Ibs ai1A) 

Old Proposed 

NI A 

2 

2 

2 

Proposed 

NI A 

- 

- 

- 

1.51 

100 

gal. 

10 

10 

10 

??? 4301 

100gal. 

8 

? ? ? ? 

8 

4 

4 

4 
Alfalfa 

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 

1.2 oz. ai 

1.2 oz. ai 

1.2 oz ai. 

0.525-1.2 

oz. ai 

0.75-0.98 

1 .O 

oz. ail 1000 

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. ail 1000 

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 

- 

1.2 oz. ai - 

1.2 oz. ai 

1 .O 

oz. ail 1000 

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 with 

Lorsbanf4E 

1 

or 3 with 

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 

1.2 oz.ai 

2.4 oz.ai 

or1.95 

3 

???? 

1.2 oz.ai 

1 

4 

2.25 oz. 

ai./1000 - 

???? 

3 Ib ai/A 

? ? ? ? 

4 

???? 

???? 4 

or 3 

in memo 

3 
Sunflowers 

A1 plant: 

T-Band 

Band 

Sweet Potato 

Pre-plant 

Broadcast 

Tobacco 

Pre-plant 

Broadcast 

Brassica crops 

At plant: 

T-Band 

Radishes 

At plant: 

In furrow 

oz. ail1000 

- 

1.2 oz 

2.0 

2.0 - 3.0 

oz. ail 1000 

0.69- 1.38 

oz. ail1000 

0.495 

oz. ai/1000 

1.2 02. 

- 

2.0 

2.0 

oz. ail 1000 

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 

Nl A 

N/A 

N/A 

10 

N/A 

N/ A 

N/ A 

Nl A 

???? 

???? 

3.0 

1.125 

40" row 

2.25 

22" row 

2.745 

???? 

???? 

2.0 

1.125 

40" row 

2.25 

22" row 

2.745 
Attachment 111. Evaluation of No-spray Buffer Zone Mitigation Proposals. 

The registrant, Dow-Agrosciences has proposed using the following no-spray buffer zones to 

reduce risks to aquatic organisms posed by chlorpyrifos spray applications. 

Background 

Application Method 

Ground Boom 

Chemigation 

Orchard Airblast 

Aerial (fixed-wing or helicopter) 

SRRD asked EFED to assess the potential mitigation of aquatic risks that could result from nospray buffer zones adjacent to aquatic areas. The procedures used in this assessment should be 

considered preliminary and are for the purpose of this exercise only. This assessment does not 

reflect EFED permanent policy or the input parameter guidance document. 

Required Setback (No-spray Zone) 

25 feet 

25 feet 

50 feet 

150 feet 

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 from the original 

RED (and EFED's input parameter guidance) has the effect of comparing results 

calculated at different percentiles. 

- 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. The problem of runoff is more complicated. For 
example, if runoff is channelized, the buffer zone would probably have little effect on 

the pesticide levels transported to the aquatic habitat. 

Risk Assessment Comparisons of No Buffer, Buffers, and No Drift Scenarios: 

Based on major chlorpyrifos crop uses 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. corn pre-plant and citrus), no use modifications were proposed in the use rates or manner 

of application, except the no-spray drift zones. In three scenarios, the registrant has proposed 

reductions in the use rate (i.e., aerial corn and tobacco) or reductions in the number of 

applications (i.e., cotton). These proposed reductions have been included in the following risk 

mitigation assessment. 

Chemical properties and fate parameters for chlorpyrifos remain the same as those used in the 

RED. To better 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). 

To estimate the spray drift amount, EFED used the PRZM input parameter, DRFT, to define the 

off-target spray drift to the standard fm pond. For the mitigation investigations related to 

buffer restriction, EFED used the AgDRTFT model (version 1.07) to predict the different DRFT 

values for different buffer restrictions. For purposes of comparison, tier 1 of the AgDRIFT 

model was used. 

The general parameters for tier 1 assessment are tabulated below. When using the AgDRIFT 

model, the user is prompted to choose tier (I, 11, or 111) and application method (aerial: ground: or 

orchard airblast). Once the tier and application method are chosen, the user then proceeds to 

toolbox function and chooses aquatic assessment to obtain the drift value. For the evaluation of 

buffer restriction, the blank for "Distance to water body from edge of field" needs to be entered. 

A "0" indicates no buffer restriction, and a numerical value (e.g., 50 ft) indicates the buffer 

restriction. The drift value, expressed as fraction of applied, is used as the "DRFT" parameter in 

the PRZM for drift loading to the EXAMS' standard farm pond. 

GENERAL PARAMETERS FOR TIER 1 ASSESSMENT 

Aerial 

Aircraft Description / Operation 

Ty pe Air Tractor AT-40 1 

Weight of Aircraft 26683 N (5998 Ib) 

Wing Semispan 7.48 m (24.5 ft) 
Flight Speed 53.6 m/s (120 mph) 

Release Height 3.05 m (10 ft) 

Nozzle Setup 

Number 42 

Vertical Offset -0.35 m (-14 in) 

Horizontal Offset -0.25 m (- 10 in) 

Boom Span *5.7 m (3~18.7 ft) 

Spacing (even) 0.28 m (1 1 in) 

Meteorology 

Wind Speed @ 2 m (6.28 ft) 4.47 m/s (10 mph) 

Wind Direction Perpendicular to Flight Path 

Surface Roughness 0.0075 m (0.005 m BCPC) 

Stability Neutral 

Relative Humidity 50 % 

Temperature 30 deg C (86 deg F) 

Test Substance 1 Application 

Specific Gravity 1 .O 

Nominal Application Rate 100 ngIcm2 (0.25 lblac) 

Swath Width 18.29 m (60 ft) 

Nonvolatile Fraction 0.03 

Number of Flight Lines 2 0 

CURVE SPECIFIC PARAMETERS 

Very Fine1 Fine1 Medium/ Coarse1 

Parameter Fine Medi um Coarse Very Coarse 

Swath Displacement 1 Swath % Swath 0 0 

DvO. l 54 mm 94 mm 164 mm 225 mm 

VMD (DvO.5) 119mm 216 mm 353 mm 463 mm 

Dv0.9 204 mm 369 mm 598 mm 789 mm 

Fraction < 141 mm 0.57 0.20 0.06 0.03 

The finelmedium droplet 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 of Buffer 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 Spray Drift 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 96 HOUR 21 DAY 60 DAY 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 96 HOUR 21 DAY 60 DAY 90DAY YEARLY 

1/10 5.694 4.770 2.634 1.488 1.128 .418 

Iowa Corn - 1 ground spray @ 3 Ib ai/A, 2" incorporation - No off-target sDrav drift 

PROB PEAK 96HOUR 21 DAY 60 DAY 90 DAY 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 @ 1.5 lb ai/A, 14-day interval - 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 @ 1.0 lb ai/A, 10-day interval - 150-ft buffer 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-day interval - No off-target spray drift 

PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY 

1/10 1.690 1.330 .8 18 .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-ft buffer 

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 60 DAY 90 DAY YEARLY 

1/10 26.433 22.213 16.837 9.383 7.245 2.608 

Mississippi Cotton - 3 aerial sprays @ 1.0 lb ai/A, 10-day interval - 150-ft buffer restrictions 

PROB PEAK 96 HOUR 21 DAY 60 DAY 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-day interval - 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 @ 5.0 lb 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-plant ground spray @ 2.0 Ib 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 

drift 

PROB PEAK 96 HOUR 21 DAY 60 DAY 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) 

(Aquatic EEC's Based on PRZM3.12-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 deep pond 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: Chlorpyrifos ground-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 freshwater fish with no spray drift. 

From the above risk 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 chronic risks 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 scenario clearly show that there 

is no level of reduction in spray drift, which will totally mitigate chlorpyrifos risks 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 or chronic risks to 

36 1 20 1 9.1 

15 1 9.3 1 4.1 

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

10.1 / 5.7 1 2.55 

sensitive aquatic animals. 

140 0.07 1 0.041 1 0.0082 
Scenario # 2. Foliar corn risk scenario with three maximum aerial applications; proposed 

use modifications include a rate reduction from 1.5 to 1 Ibs ai./A and a 10-day retreatment 

interval versus a previous 14-day interval. 

Risk Quotients for Corn in Pottawattamie Co., Iowa 

(Foliar, Aerial Spray; 3 Applications at 1.5 Ibs ai./A reduced to 1 Ib ai/A) 

(Aquatic EEC's Based on PRZM3.12-EXAMS Model) 

Exposures (pglL) Toxicity Risk Quotients 

No Buffer I Buffer 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 deep pond or estuarine water 

2 1 -Day EECs in 2-meter deep pond or estuarine water 

17.1 15.1 1 1.69 

17.1 15.1 1 1.69 

Estuarine Algae EC,, 

Risk Summary for 3 Aerial, Foliar Spray Applications to Corn at the 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 as three aerially, foliar spray applications at 1.5 and 1 Ib ai/A 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 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 70 percent. However, the risk quotients for the no-drift scenario clearly 

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/>370 
show that the use of no-spray buffer zones can not totally mitigate chlorpyrifos risks to aquatic 

animals. About 10 percent on 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 risks to sensitive 

aquatic animals. 

Scenario # 3. Two foliar airblast applications to Florida citrus with 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) 

(Aquatic EEC'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 I No Drift 

20.8 1 20.6 I 20.0' 

20.8 1 20.6 I 20.0' 

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 1 20.0 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 11 for acute 

74 174 1 71 

60 111 1 4.6 

0.035 590 I 590 I 570 
freshwater fish, which assumes no spray drift at all. From the above risk quotients, it is 

apparent that runoff alone from air-blast spray applications to 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 1 percent. 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 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 interception by 

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 to Mississippi cotton; with proposal to reduce use 

to three aerial applications and 10-day retreatment intervals. 

Risk Quotients for Cotton in Jackson Co., Mississippi 

(Foliar, Aerial Spray; 6 versus 3 Applications at 1 lb ai./A) 

(Aquatic EEC'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 > 1200 1>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 Spray Applications to 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 lb ai/A 

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 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 80 percent. 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 10 percent 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 0.19 I 0.038 I 0.019 
risks to sensitive aquatic animals. 

Scenario # 5. One Pre-plant Ground Application to North Carolina Tobacco; with proposal to 

reduce use rate to 2 Ibs ai./A from 5 Ibs ai./A and 2" soil incorporation versus 4". 

Risk Quotients for Tobacco in Wake Co., North Carolina 

(Pre-plant, Ground Spray; 5 Ibs ai./A & 4" incorportation versus 2 Ibs ai./A & 2" incorp.) 

(Aquatic EECts Based on PRZM3.12-EXAMS Model) 

Species 

11 Freshwater Fish Acute LC, 40.4 I 14.0 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 I Buffer 1 No 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 

. . ' 2 1-Day EECs in 2-meter deep pond or estuarine water 

400 1140 I 110 

0.04 

Risk Summary for 1 Pre-plant Ground Spray Application to Tobacco at Maximum Use Rate: 

1000 1350 1180 

410 1 140 1 110 

40.4 I 14.0 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" soil incorporation 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 acute freshwater 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 65 percent. 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 ~,ssn 
clearly show that the use of no-spray buffer zones can not totally mitigate chlorpyrifos risks to 

aquatic animals. About 27 percent 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 risks to 

sensitive aquatic animals. 

Conclusions: The no-spray zones proposed by Dow AgroSciences each reduce the risks to aquatic 

animals compared to the current use methods. However, none of the buffer zones totally mitigate the 

risks to aquatic animals. The no-spray drift assessment indicates that spray drift restrictions alone can 

not totally mitigate risks for even one aquatic group. According to the PRZM-EXAMS Model, the 

EECs from runoff of chlorpyrifos from treated fields, alone, are sufficiently high to pose risks to all 

aquatic animal categories: both acute and chronic.