UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES,
AND
TOXIC
SUBSTANCES
PC
Code:
106901
DP
BARCODE:
D282962
MEMORANDUM
July
24,
2002
SUBJECT:
Asulam:
Response
to
Registrant
Comments
on
Drinking
Exposure
Estimates.

TO:
Demson
Fuller
Special
Review
and
Reregistration
Division
(
7508C)

FROM:
Norman
Birchfield,
Ph.
D.
Biologist
Environmental
Risk
Branch
4
Environmental
Fate
and
Effects
Division
(
7507C)

THRU:
Betsy
Behl,
Chief
Environmental
Risk
Branch
4
Environmental
Fate
and
Effects
Division
(
7507C)

Aventis
has
submitted
brief
comments
titled
 
Asulam:
Revised
Tier
1
Drinking
Water
EECs
for
use
in
the
Human
Health
Risk
[
Asessment] 
on
the
drinking
water
assessment
conducted
for
asulam
(
January
3,
2002,
D279761).
EFED
has
reviewed
the
Aventis
comments
a
determined
that
no
change
is
necessary
in
the
current
drinking
water
assessment.
EFED
has
identified
environmental
fate
studies
necessary
to
confirm
the
conclusions
of
the
drinking
water
assessment.

Aventis
disagrees
with
the
proposed
drinking
water
exposure
values
determined
by
EFED
through
analysis
of
groundwater
monitoring
data
and
FIRST
surface
water
modeling:

Groundwater:
Aventis
states
that
detections
of
asulam
in
groundwater
outside
the
application
area
were
a
result
of
contamination
from
applications
of
asulam
applied
around
the
wells
to
prevent
weeds
from
growing
up
around
the
wells
(
a
use
not
registered
for
asulam)
and
from
contamination
resulting
from
alleged
spills
at
mixer
loader
sites.
Neither
of
these
scenarios
proposed
to
result
in
the
groundwater
contamination
levels
described
in
the
January
3,
2002
drinking
water
assessment
were
documented
and
appear
to
be
speculation.

The
registrant
also
states
that
the
analytical
results
on
asulam
concentrations
in
groundwater
do
not
need
to
be
corrected
for
incomplete
recovery
but
fails
to
state
why.

EFED
maintains
that
the
groundwater
concentrations
presented
in
the
January
3,
2002
drinking
water
assessment
reflects
the
current
understanding
of
the
environmental
fate
and
behavior
of
asulam.

Surface
Water:
Aventis
states
that
the
surface
water
monitoring
study
conducted
in
Florida
and
Louisiana
provides
a
more
accurate
estimates
of
drinking
water
exposure
and
that
EFED s
FIRST
model
estimates
are
more
than
100­
times
higher
than
monitoring
results.

The
FIRST
model
is
intended
to
estimate
conservative
acute
and
chronic
drinking
water
concentrations.
FIRST
estimated
concentrations
are
unlikely
to
be
measured
in
a
small
scale
monitoring
study
because
they
would
not
occur
often
and
or
be
widespread.
Monitoring
studies
such
as
that
conducted
by
the
registrant
are
useful
for
characterizing
exposure,
however,
due
to
the
monthly
sampling
frequency,
small
number
of
sampling
locations,
and
short
study
duration,
these
studies
are
not
normally
adequate
to
provide
a
conservative
estimate
of
exposure
via
drinking
water.

EFED
maintains
that
the
FIRST
estimates
provided
in
the
January
3,
2002
drinking
water
assessment
are
presently
the
most
reliable
conservative
estimates
of
exposure
to
asulam
via
drinking
water
derived
from
surface
water.

In
reviewing
the
data
set
for
asulam,
a
number
of
deficiencies
were
noted.
The
following
studies
are
requested
to
confirm
fate
parameters
used
to
estimate
drinking
water
exposures:

162­
1
(
835.4100)
Aerobic
Soil
Metabolism
(
three
soils)
162­
2
(
835.4200)
Anaerobic
Soil
Metabolism
162­
3
(
835.4400)
Anaerobic
Aquatic
Metabolism
162­
4
(
835.4300)
Aerobic
Aquatic
Metabolism
Previously
conducted
studies
did
not
adequately
identify
major
asulam
degradates.

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