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www.wileyrein.com August 6, 2010

Via Electronic Mail and US Mail

Mr. Jeffrey L. Dawson U.S. EPA - Office of Pesticide Programs One Potomac Yard 2777 Crystal Drive Arlington, Virginia 22202

Re: Follow-up on Conference Call Di scussing Field Flux Studies

Dear Jeff:

This letter follows up on the July 6, 2010 conference we had with OPP staff regarding the Field Flux Studies submitted by the Methyl Bromide Industry Panel (MBIP). During the call EPA requested a dditional information from the MBIP in three areas: (1) the applicab ility of the California flux st udy data to other geographic regions; (2) the uptake of speci alized tarps in Florida; a nd (3) an update on VIF/TIF for broadcast applications of methyl brom ide. The requested information on these topic is provided below.

1. California Flux Data Repres entative of Other Regions:

The California flux study (Wasco, June 2009 MRID # 48006001) encompassed three fields addressing three variations of the shallow broadcast application method. Pursuant to our March 2009 flux study proposal, the MBIP also conducted a study in Florida in January 2010 (MRID # 48107601). The Florida study was designed to includ e the shallow broadcast method and was intended to serve as confirmatory data in support of the California study. It was also intended to show that emission rates from Florida conditions would be lower than the California study.

As you know, due to bad weather and equipment-related problems, the shallow broadcast portion of the Florida study was disqualified by the study director (Dr. H. Ajwa). Nonetheless, it would be scientifically appropriate and conservative to use the California data to calculate buffer zones for broadcast fumigation in Florida and other regions of the US.Mr. Jeffrey Dawson August 6, 2010 Page 2

As we explained on the conference call, the conditions under which the California study were conducted represent th e worst-case for conditions that may be encountered in all regions. Specificall y, the California study was conducted in the southern area of the San Joaquin Valley, during late-spring/early summer (relatively high ambient temperatures), on a light soil (s andy loam), and with the target soil moisture (~70% of field capacity) achieve d. By comparison, the Florida study was conducted in the winter and the data th at would have been generated for the broadcast application method would have b een from light soil with moisture level that exceeded 100%.

Flux data now available indicate that emission rates are directly impacted by higher soil moisture. Florida fields c onsistently have moisture capacities approaching or exceeding 100% due to their sandier soils. Because the California study involved soils with significantly less soil moisture, the emission levels generated in the California study for the br oadcast method are much higher than the levels that likely would have been docume nted in the Florida study if the broadcast portion had not been disqualified.

The chloropicrin flux studies listed in Table 1 show that fumigant emissions under Florida’s more moist cond itions are, at most, equal to, and typically less than emissions from California. The same would be true for methyl bromide. For the shallow broadcast tarp application method, th e peak chloropicrin emission rate was higher in California (2008) than in Fl orida (1995 and 2009) and Washington (1996); where polyethylene tarp was used in a ll studies. For the tarped bedded shank application method, the peak chloropicrin emission rate was higher in California (2008; polyethylene tarp) than in Flor ida (2009 and 2010; metalized, VIF or TIF tarps) and Georgia (2009; polyethylene ta rp). For both application methods, the chloropicrin emissions were highest in California.

This same trend would hold true fo r shallow broadcast applications of methyl bromide, as shown by the much lower methyl bromide emissions we recently obtained in Florida for the othe r application methods compared to the historical flux data (1990s) derived from the older Califor nia studies that EPA used to support the buffer zone calcu lations underlying the RED.Mr. Jeffrey Dawson August 6, 2010 Page 3

Table 1. Comparison of Chloropicri n Peak Emissions by Application Method Across Different States. Application Method MRID # (Year of Study) Location of Study Soil Sealing Test Substance Peak Chloropicrin Emission (μg/m 2 /sec) 1
47576901

(2008) California Polyethylene tarp Chloropicrin 37

44149201

(1995) Florida Polyethylene tarp Chloropicrin 29

44149201

(1996) Washington Polyethylene tarp Chloropicrin 12

48085701

(2009) Florida Polyethylene tarp; standard rig Pic-Clor 60 36.6 Shallow Broadcast Tarp

Polyethylene tarp;Chellemi lowdisturbance rig Pic-Clor 60 36.8

47576901

(2008) California Polyethylene tarp; strip 2 Chloropicrin 40

47813901

(2009) Florida Metalized tarp Chloropicrin 7.7

47813901

(2009) Florida VIF Chloropicrin 2.0

47813901

(2009) Florida Metalized tarp Chloropicrin 1.2

4782001

(2009) Georgia VIF Paladin 79/21 4 1.8

4782001

(2009) Georgia Polyethylene tarp with rototill Paladin 79/21 4 13.3

4782001

(2009) Georgia Polyethylene tarp without rototill Paladin 79/21 4 15.0 Tarped Bedded Shank

48107601 (2010) Florida TIF Tri-Con 50/50 5 10.5

1 Peak emission rate normalized to 175 lbs/acre for comparison purposes.
2 Pic-Clor 60 is contains approxi mately 60% chloropicrin and 40% 1,3- Dichloropropene.
3 Shallow strip (flat fume) is functionally equivalent to bedded shank.
4 Paladin 79/21 contains approximate ly 79% DMDS and 21% chloropicrin.Mr. Jeffrey Dawson August 6, 2010 Page 4

4 Tri-Con 50/50 contains approximately 50% methyl bromide and 50% chloropicrin.

2. The Use of Non-Polyethylene Row Mulch in Florida

You also asked us for informati on on the use of films in row mulch agriculture in Florida. Based on availabl e information, we understand that almost all growers in Florida (98%) have switc hed away from polyethylene films to VIF/TIF or metalized films as their choice for methyl bromide applications in row mulch use patterns. Of the 98%, approximately 70% of this uptake has been in the form of VIF, and 30% has been in the fo rm of metalized film. (In some specific instances, the VIFs are also metalized.) This particular row mulch use pattern is applicable to methyl bromide bedded shank applications only; where tarp preferences are becoming tailored to speci fic products. For example, Pic-Clor 60 applied via tarped bedded shank has a use pattern that is 70% polyethylene film, 20% VIF, and 10% metalized film.

3. Additional Information on Co mmercial Use of Broadcast TIF/VIF.

During our call, you also asked for additional information on the use of TIF/VIF in broadcast applications.

• Application Experience: Deployment trials, large demonstrations, and commercial use of broad cast (13-foot wide) VaporSafe TM (or any other low-permeability film) i ndicate that normal “maximum acres-per-day” applications can be maintained; where a typical rig can lay about 17-25 broadcast acres per day, depending on the field layout.

• Gluing: Seam failure has been one of the traditional primary problems with these low-permeability films. Several groups have been working on resolving the gluing issue for years, and various materials and/or methods have been developed and continue to be refined. Commercial viability has been achieved for some methods already, and more gluing methods/opti ons will likely be identified in time to meet the field-implemen tation of the 2011 RED labels.Mr. Jeffrey Dawson August 6, 2010 Page 5

• Commercial Example -- USDA-APHIS Pale Cyst Nematode Quarantine in Idaho: 13-foot VaporSafe TM (TIF) was used on 49 acres in Idaho in May 2010. All acr es were treated with 400 lbs/acre of MB 98/2. In this particular cas e, Trident Ag Products and TriCal, Inc. used the “band-aid” gluing sy stem developed by TriCal, Inc. to seam the broadcast film panels ( See Photo 1 and Photo 2 below). The band-aid system uses standard, solvent-based glue to adhere the panels of VaporSafe TM (or any other low-permeability film) together, while simultaneously applying a smaller roll (14-20” wide) of polyethylene film over the top of the seam. Because the solvent in the glue can readily volatilize thr ough polyethylene film, this upper seam-covering layer of polyethy lene film anchors the two VaporSafe TM seams together quickly; thereby providing more time for the glue between the VaporSafe TM panels to cure.

Photo 1 Photo 2Mr. Jeffrey Dawson August 6, 2010 Page 6

We trust that the foregoing addresses the Agency’s information requests. If you need additional information, please do not hesitate to contact me at the number or e-mail address listed above.

Sincerely,

/s/

Tracy Heinzman Counsel to MBIP, LLC

cc: Steve Weiss, OPP/PRD Sue Bartow, OPP/PRD MBIP Members