Document ID: EPA-HQ-OPP-2006-0239-0031
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-04-22T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.  C.  20460

				OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

Chemical:  123802

DP Barcode: 337939

MEMORANDUM

DATE:		February 12, 2009

SUBJECT: 	Transmittal of Environmental Fate, Ecological Risk and
Endangered Species Assessment in Support of the Registration Review of
Fomesafen Sodium (PC123802)

FROM:	Paige Doelling, Ph.D., Fisheries Biologist

		Steve Wente, Biologist

Nancy Andrews, Ph.D, Branch Chief

		Environmental Risk Branch 1

Environmental Fate and Effects Division 

TO:		Wilhelmena Livingston, Chemical Review Manager

		Special Review and Registration Division

Attached is the Environmental Fate, Ecological Risk and Endangered
Species Assessment in Support of the Registration Review of Fomesafen
Sodium (PC123802) and supporting appendices.  Key findings of the
assessment are summarized below.

Fomesafen is an herbicide, applied as a foliar spray (both pre-emergent
and post-emergent) for control of broad-leaved weeds, grasses, and
sedges.  Currently it is registered for use on soybeans, cotton, dry
beans and snap beans under FIFRA Section 3. Mode of action is via
cellular membrane disruption.  It is persistent in soil and surface
waters, and has the potential to leach to ground water.  Based on
physical properties, bioaccumulation and long-range transport are not
expected to be of concern.  It is extremely toxic to terrestrial plants,
but of fairly low acute toxicity to fish and wildlife.  Some chronic
reproductive effects have been noted in mammals, and may also occur in
birds. No major degradates of toxicological concern have been
identified.

Ecologically, the organisms most at risk from fomesafen are terrestrial
plants, especially dicots.  Because terrestrial plants are important
both ecologically (they provide a critical part of both the structure
and function that defines “habitat”) and economically (nearby
non-target, non-treated crop plants may be affected), these potential
impacts are an important consideration.  No LOCs were exceeded for
aquatic endpoints except the listed species LOC for freshwater
non-vascular plants.  At the time of this assessment, there were no
listed non-vascular freshwater plants, and no listed species had been
identified as having an obligate relationship with freshwater
non-vascular plants.  For terrestrial organisms, chronic LOCs were
exceeded for birds (and by extension, reptiles and amphibians) at all
but the lowest application rate.  Chronic LOCs were exceeded for mammals
only for small herbivorous mammals at the highest application rate. 
Chronic LOC exceedences apply to both listed and non-listed species.  

For terrestrial plants, using drift estimates based on the more
sensitive dicots, effects should be anticipated as far as 850 ft for
ground applications, and 1,000 ft for aerial applications.  An analysis
of the impact of modifying droplet size spectrum and the differences in
aerial versus ground application methods has been included in the risk
description.  Based on spray drift estimations, clearance distances for
chronic exceedences are well within the clearance distances for
terrestrial plants, thus if terrestrial plants are protected, then by
virtue of sensitivity, other vulnerable organisms should be protected as
well.  Clearance distances for chronic effects on birds, reptiles,
amphibians, and mammals are 10 ft from the application source for ground
applications (based on low boom estimates) and 100 ft for aerial
applications (based on application parameters used in AgDrift Tier I
estimates).  

For listed animals, both aquatic and terrestrial, the primary risk posed
by use of fomesafen as currently registered under Section 3 is due to
potential degradation of plant communities providing food, shelter, or
protection from predators.  On the basis of these indirect effects and
the anticipated magnitude of such effect, an overall determination of
may affect, likely to adversely affect applies to all listed species
located with 850 ft of the application location.  The action area, based
on the furthest extent at which an LOC is exceeded (dicots), is 1,000 ft
away from agricultural land in geographic areas where fomesafen is
registered for use.  No direct effects are anticipated for aquatic
organisms, constituting a no effect determination for these organisms on
the basis of direct effects.  Based on available data, there is a
chronic risk to birds, reptiles, and terrestrial-phase amphibians.  The
Agency is unable to evaluate the potential magnitude of these chronic
effects, thus the overall determination for these taxa is may affect,
likely to adversely affect.

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