Chlorsulfuron Focus Meeting Summary

December 6, 2012 

11:00am - 12:30pm

Attendees

E.I. DuPont de Nemours and Company (DuPont):  Aldos Barefoot, Dave W.
Saunders, Craig M. Alford, Cecilia Much Hirata, Richard J. Ambrose

Environmental Protection Agency (EPA or Agency): Kaitlin Keller (PRD),
Patricia Parrott (PRD), Monica Hawkins (HED), Sheila Piper (HED,
Christine Olinger (HED), Mary Clock-Rust (EFED), Ed Scollon (EFED),
Katrina White (EFED), Cynthia Doucoure (BEAD), Stephen Smearman(BEAD)

Objective

The purpose of the meeting was for members of the EPA’s Pesticide
Re-evaluation Division (PRD),  Environmental Fate and Effects Division
(EFED), Biological and Economic Analysis Division (BEAD), and Health
Effects Division (HED)  to meet with DuPont, a technical registrant for
chlorsulfuron, for the following reasons: 1) discuss European Union
studies on chlorsulfuron degradates that EPA requested be submitted for
review; 2) discuss annual usage information needed for the registration
review human health and ecological risk assessments; 3) discuss use of
chlorsulfuron on uncultivated areas and intermittently flooded areas as
well as potential label clarifications for these uses; 4) discuss label
language to reduce spray drift.  

Discussion

Degradate and Metabolite Information

On October 25, 2012, EPA provided DuPont with a list of degradate
studies submitted to the European Union (EU) to support European
registrations of chlorsulfuron and requested that DuPont submit these
studies for review.  On November 29, 2012, DuPont submitted six EU
studies on chlorsulfuron degradates as requested for the registration
review of chlorsulfuron.  DuPont provided an overview of the findings in
these studies in the meeting as well as an overview of the environmental
fate and physical chemistry properties of chlorsulfuron.  EPA indicated
it would be useful to have the foreign soil classifications on studies
submitted that were conducted on foreign soils using the guidance
available at:
http://www.epa.gov/oppfead1/international/naftatwg/projects/regulatory/s
oil-crosswalks.pdf.

Use/Usage Information

DuPont provided a list of active registrations for the EPA to
cross-check with those EPA believes are active registrations.  DuPont
also provided usage information in terms of amounts used in pounds per
year nationally and regionally by product and use category (in terms of
cereal products, range and pasture products, and vegetation management),
noting that this information can be broken down by state and will be
submitted to the Agency.  EPA agreed that a breakdown of the data by
state would be helpful.   DuPont also indicated that they are working
toward standardizing placement of application use information on all
DuPont chlorsulfuron labels and will provide EPA with a master
spreadsheet that tabulates all chlorsulfuron use information, such as
use sites, application timing, application methods, single maximum and
seasonal maximum uses rates and minimum retreatment intervals.

Label Clarifications

DuPont provided an overview of chlorsulfuron products used and the
intended use definition for uncultivated areas.  EPA and DuPont agreed
that DuPont products are not intended for use in residential settings. 
EPA explained that unless products specifically prohibit residential
use, EPA would conduct a residential assessment because certain
chlorsulfuron uses, such as ornamentals and various uncultivated area
sites, could be used by residential homeowners.  DuPont agreed to work
with EPA to develop appropriate language for labels that would prohibit
residential use prior to the risk assessment phase of registration
review.  

Additionally, DuPont further clarified the intermittently flooded areas
use of chlorsulfuron.  DuPont stated that the intended use is primarily
in the Western United States as a spot treatment in areas that would
flood during spring snow melt and runoff.  Moisture in these areas makes
them prone to noxious weeded which landowners are required by state
regulators to control.  Based on the intended use for flooded areas, EPA
and DuPont agreed that label language could be better defined.  EPA also
explained that more descriptive use sites could help reduce conservative
assumptions in ecological risk assessments.  Additionally, EPA requested
more information on the size of the spot treated for intermittently
flooded areas.  DuPont agreed to work with the Agency to develop label
language that more accurately defines this use and to provide
information on the size of a spot treatment for this use.  

Spray Drift

DuPont reviewed spray drift requirements and recommendations required by
the 2005 Reregistration Eligibility Decision (RED) and indicated that
most products do have all appropriate spray drift mitigation on the
labels.  Two products are missing the requirement for a maximum boom
height of 10 feet above target vegetation for aerial applications. 
However, DuPont noted that this is the default height in practice. 
DuPont committed to ensuring that the two product labels without this
language are updated prior to the registration review risk assessment
phase. 

Follow-up

DuPont will provide the foreign soil classification for studies
submitted that were conducted on foreign soils.

DuPont will provide EPA with overall annual chlorsulfuron usage by
product broken down by state and EPA Region.

DuPont will provide EPA with a master spreadsheet of all DuPont
chlorsulfuron product use information. 

DuPont will provide EPA with the size of a typical spot application of
chlorsulfuron on intermittently flooded areas.

DuPont will ensure that spray drift label language is updated on the two
DuPont products currently missing the 10 ft. aerial application maximum
boom height restriction.

EPA will work with DuPont to develop revised label language to clearly
prohibit residential use of chlorsulfuron and better define
intermittently flooded areas.

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