			

May 15, 2008

Peter Caulkins 

Associate Director 

Special Review and Reregistration Division 

Office of Pesticide Programs

U.S. Environmental Protection Agency  

Ariel Rios Building 

1200 Pennsylvania Avenue N. W. 

Mail Code: 7508P 

Washington, DC 20460

Dear Peter:

Thank you for your memorandum of April 8, 2008, regarding the USDA
Agricultural Research Service (ARS) research related to permeability of
plastic films used for soil fumigation.  

Nearly all the permeability data that ARS has collected specific to
individual brands of films has come from two area-wide projects that ARS
has funded, one in Florida and other southeastern states and the other
in California, Oregon, and Washington.  Most of these large-scale,
on-farm tests have been through 1 year of testing, although some are
starting new this year.  The tests are designed to test the efficacy of
methyl bromide alternatives under actual farming conditions and to
transfer methyl bromide alternatives to farmers.  ARS expects to
continue funding these projects for a total of 5 years.  As part of
these tests and to better understand results of tests with different
alternative fumigants and different films, ARS is conducting ongoing
tests to determine the permeability of the films being used in field
trials.  ARS has resources to test only those specific films that will
be used in experiments as part of the area wide project and has no plans
to do extensive testing of all brands or all types of films within any
specific brand.  A conservative estimate is that ARS will test only
about 10 percent of existing films, and new films are constantly being
developed.

Given that the ARS research projects are just getting under way, that
considerable time is necessary for replication over location and time,
and that at least several months are needed for the review that occurs
as a part of the publication process, it doesn’t seem likely that the
limited data ARS is collecting would be available within a time frame
useful for EPA to use in its regulatory setting process.  And as alluded
to above, the usefulness of ARS data would be minimal because of the
limited nature of tests relative to the number and types of films
included in our field trials; that films are not tested over a range of
environmental conditions that might affect their fumigant permeability
and that the experimental designs were specifically written to test the
efficacy of alternative fumigants and other methyl bromide alternatives,
not films.

ARS understands that the new EPA fumigant regulations currently being
written are of great importance to our customers, the farmers.  In the
spirit of the close cooperation that has existed between ARS and EPA for
many years with respect to the methyl bromide issues and to help
facilitate adoption of alternatives by farmers, I can assure you of
ARS’ willingness to assist EPA in any way we can, consistent with our
mission and resources.  As an example of the type of assistance that
might be useful to you, ARS might provide samples of film taken from our
experiments for you to test in your laboratories or by contractors.  An
advantage of this collaboration would be that the film would have been
installed using regular farming practices and exposed to existing
environmental factors just as would happen during normal farming
activity.  ARS would be happy to discuss sampling and weathering
parameters with EPA scientists if that would be useful and would collect
the samples however EPA specified.  

ARS permeability testing is being conducted in the laboratory of Dr.
Scott Yates at the ARS laboratory in Riverside, California, using a
method he published.  As you know, there are other methods available to
conduct permeability tests.  If EPA chose to use Scott’s method, Scott
would be happy to provide technical assistance to EPA scientists or
contractors, if requested by EPA, to allow EPA to get up to speed
quickly.

Please call me if you have questions or comments or if you would like to
discuss further how ARS might assist you in obtaining the information
you require.

Sincerely,

/s/

Kenneth W. Vick

Senior National Program Leader

Post Harvest Entomology 

	

United States Department of Agriculture

Research, Education, and Economics

 National Program Staff

George Washington Carver Center ( 5601 Sunnyside Avenue

Beltsville, MD.  20705-5148

An Equal Opportunity Employer

 

 

