Document ID: EPA-HQ-OPP-2006-0239-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-03-28T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.  C.  20460

				OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

	Chemical:  Fomesafen

	PC Code:  123802

DP Barcode: 302766, 314014, 314112 

MEMORANDUM

DATE:		January 30, 2006

SUBJECT: 	Ecological Risk Assessment for New Uses of Fomesafen on Cotton
(DP 302766), Snap Beans (DP 314014), and Dry Beans (DP 314112)

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

		James Hetrick, Ph.D., Senior Chemist				

Nader Elkassabany, Acting Branch Chief

		Environmental Risk Branch 1

Environmental Fate and Effects Division (7507C)

PEER REVIEWERS:	Edward Odenkirchen, Ph.D., Senior Scientist		

	Environmental Risk Branch 1

	Kevin Costello, Fate Scientist

			Environmental Fate and Effects Division (7507C)

TO:		Joanne Miller, Product Manager, Herbicide Branch (23)

		Barbara Madden, Risk Integration, Minor Use, 

			Emergency Response Branch

		Registration Division (7507C)

Attached please find the Environmental Fate and Effects Divisions’s
(EFED) environmental risk assessment for the proposed use of fomesafen
(PC 123802) on cotton, snap beans, and dry beans.  Fomesafen is proposed
as a pre-plant, and pre- or post-emergent herbicide.   It is currently
registered for use on soybeans, and has been the subject of a number of
Section 18 actions.  Methods of application assessed include aerial
spray (0.375 lb ai/A) and ground spray (0.50 lb ai/A).  An alternative
ground spray application rate (0.2 lb ai/A) was also considered.  

Sufficient fate and toxicity data were available to conduct a screening
level assessment.  The majority of the studies used were submitted to
the Agency in the 1980’s, when fomesafen was initially registered. 
Existing fate studies were re-reviewed to establish half-lives, and new
data evaluation reviews (DERs) were generated.  Revised fate DERs will
be transmitted under separate cover.  In some cases, aquatic toxicity
tests were conducted on formulations, rather than the active ingredient.
 If necessary, concentrations were corrected for percent active
ingredient, and endpoints re-calculated.  Details of the toxicity
corrections are contained in the ecological effects data appendix.  In
support of the registration action, EFED requested and the registrant
submitted seven aquatic and terrestrial plant toxicity studies (MRIDs
46673801-46673807).  Based on initial review, these studies have
provisionally been classified supplemental, and the data from them has
been used in the risk assessment.  These studies are currently
undergoing the full review process, and the classification of the
studies may be modified.  DERs for these studies will be provided to RD
at a later date, under DP 323262.  Existing avian reproduction studies
did not establish a lowest observable adverse effect concentration
(LOAEC), so there is significant uncertainty associated with the chronic
bird component of the assessment.

Key findings of this assessment include:

(	The greatest acute risk associated with fomesafen use was for
non-target terrestrial plants.  Due to the high toxicity of the compound
to terrestrial plants and proposed high application rates, spray drift
buffers will likely have a minimal impact on reducing risk to non-target
plants unless they are extremely wide (>900 ft for aerial applications,
>350 ft for ground applications).

(	Degradation of plant communities (hedgerows, wetlands, riparian
corridors) surrounding the treated fields could have effects on the
wildlife residing in or dependent on them.  

(	A significant concern is the persistence and mobility of fomesafen in
both soil and aquatic environments. 

(	Accumulation in the soil of a field repeatedly treated with fomesafen
may adversely affect crops subsequently planted in the field.  Effects
from a single treatment may persist for 3-18 months.

(	Concentrations of fomesafen in shallow groundwater used for irrigation
purposes may be high enough to adversely affect crops subsequently
planted in the field.

(	Fomesafen is practically non-toxic to slightly toxic to aquatic
animals, both freshwater and estuarine/marine.  No adverse effects to
aquatic animals are anticipated based on proposed rates.

(	Fomesafen does exert toxic effects on aquatic plants but risk
quotients (RQs) for the scenarios modeled were below the level of
concern (LOC).

(	Fomesafen is practically non-toxic to slightly toxic to birds and
mammals on an acute basis.  Chronic reproductive effects were noted in
rats.  A chronic LOAEC for birds was not established.  No acute risk
LOCs were exceeded, but acute endangered species LOCs were exceeded for
small mammals at application rates of 0.5 and 0.375 lb ai/A, but not at
0.2 lb ai/A.  Some chronic RQs for both birds and mammals exceeded the
LOC at all application rates.  The meaning of the exceedence for birds
is uncertain, as the guideline study submitted did not determine a
LOAEC.  Better data may significantly affect the chronic risk picture
for birds.

Endangered Species

(	Based on LOC exceedences, the following taxa of endangered species
were identified as potentially being at risk from fomesafen use:
amphibians (terrestrial phase), birds, dicotyledon plants, mammals,
monocotyledon plants, and reptiles.  A LOCATES search (Ver 2.2.11)
showed 807 unique endangered species are known to occur in counties
growing cotton, snap beans, and dry beans.  Of these species, 627 (78%)
are plants.  A significant number of these plants are endemic to Hawaii
and California.

(	Fomesafen is likely to affect plants near the treated areas, with
potential effects extending to >900 ft away from the treatment source in
the case of aerial application.  Direct effects (reduction of growth,
survival, or fecundity) may occur for endangered plants in the drift
zone.  Effects on non-endangered plants in the drift zone may constitute
indirect effects (reduction of food or cover) on endangered animals.

(	Based on an analysis of food habits and size, only 5 species of listed
mammals appear to be in the direct acute risk category, at the maximum
application rate (0.5 lb ai/A).  Reduction of the application rate to
0.375 lb ai/A reduces exposure sufficiently that RQs for these organisms
drop below the LOC.

(	Based on an analysis of food habits and size, 13 species of mammals
appear to be in the chronic risk category.  RQ values for birds are used
to estimate risk for reptiles and amphibians.  Based on current chronic
bird data, there may be chronic risk for birds, reptiles and amphibians
at the proposed application rates of 0.5 lb ai/A and 0.375 lb ai/A. 
Reduction of the application rate to 0.2 lb ai/A reduces exposure
sufficiently that RQs for all animals except 2 reptiles drop below the
LOC.

Data Requirements

In general, providing updated fate and/or toxicity studies to the Agency
may reduce uncertainty in the risk assessment.  Specific studies that
may affect risk conclusions include:

(	Avian Reproduction Study (71-4).  The study the Agency currently has
does not establish an LOAEC, only an NOAEC of approximately 50 ppm for
both bobwhite quail and mallard duck.  This NOAEC is based on the
highest dose tested, and the actual no-effects may be higher.

  

 PAGE   

 PAGE   1