TXR
NO.
0050454
February
5,
2002
MEMORANDUM
SUBJECT:
ASULAM­
Report
of
the
FQPA
Safety
Factor
Committee
FROM:
Carol
Christensen,
Acting
Executive
Secretary
FQPA
Safety
Factor
Committee
Health
Effects
Division
(
7509C)

THROUGH:
Ed
Zager,
Chair
FQPA
Safety
Factor
Committee
Health
Effects
Division
(
7509C)

TO:
Jose
Morales
Reregistration
Branch
III
Health
Effects
Division
(
7509C)

PC
Code:
106901;
106902
The
FQPA
Safety
Factor
Committee
evaluated
the
available
hazard
and
exposure
data
for
asulam
on
December
10th
,
2001
and
made
the
recommendation
for
the
FQPA
safety
factor
to
be
used
in
human
health
risk
assessments
(
as
required
by
Food
Quality
Protection
Act
of
August
3,
1996).
The
committee
concluded
that
the
FQPA
safety
factor
be
retained
(
10x)
in
assessing
the
risk
posed
by
this
chemical.
I.
HAZARD
ASSESSMENT
(
Memorandum:
J.
Morales
to
C.
Christensen
dated
December
3rd
,
2001)

A.
Adequacy
of
the
Toxicology
Database
The
toxicology
data
base
for
asulam
is
complete
for
FQPA
assessment.
The
toxicology
database
for
asulam
was
reviewed
by
the
Hazard
Identification
Assessment
Review
Committee
(
HIARC)
on
November
13th
,
2001.
Asulam
was
also
reviewed
by
the
Mechanism
of
Toxicity
Assessment
Review
Committee
(
MTARC)
on
September
27,
2001
to
consider
the
mechanism
of
thyroid
toxicity.
Prenatal
developmental
toxicity
studies
in
the
rat
and
rabbit
and
a
two­
generation
reproduction
study
are
available
with
asulam.
The
HIARC
determined
that
a
developmental
neurotoxicity
(
DNT)
study
is
not
required.
However,
HIARC
recommended
the
requirement
for
a
comparative
thyroid
rat
assay
in
adults
and
offspring.
(
See
HIARC
Report
TXR­
0050324)

B.
Determination
of
Susceptibility
No
quantitative
or
qualitative
evidence
of
increased
susceptibility
was
demonstrated
in
either
the
prenatal
developmental
toxicity
study
in
rats
or
in
the
prenatal
developmental
toxicity
study
in
rabbits.
There
was
evidence
of
quantitative
susceptibility
in
a
two­
generation
reproduction
study
in
the
rat.

II.
EXPOSURE
ASSESSMENTS
A.
Dietary
Food
Exposure
Considerations
(
Memorandum:
J.
Morales
to
C.
Christensen
on
December
3rd,
2001)

Asulam
(
methyl­
4­
sulfanilylcarbamate)
is
a
postemergent
systemic
carbamate
herbicide
marketed
under
the
trade
name
ASULOX
®
Herbicide
by
Aventis
CropScience.
Asulam
is
primarily
used
in
agriculture
with
key
markets
in
Florida
and
Louisiana.
ASULOX
®
contains
the
sodium
salt
of
asulam
and
is
registered
for
use
on
sugarcane
as
a
3.34
lb/
gal
soluble
concentrate/
liquid
(
SC/
L)
formulation.
This
formulation
may
be
applied
postemergence
as
a
band
or
broadcast
application
using
ground
or
aerial
equipment
or
as
a
spot
treatment.
The
asulam
use
rate,
for
sugarcane,
ranges
from
2.5
to
3.34
lbs
a.
i./
A
and
can
applied
up
to
two
times
per
year.
Tolerances
are
listed
at
40
CFR
180.360
and
range
from
0.05­
30
ppm.
Apart
from
its
food
use
on
sugarcane,
asulam
is
used
on
Christmas
tree
plantations,
ornamentals,
turf
(
sod
farms
only)
and
non­
cropland
uses.

The
qualitative
nature
of
the
residue
in
plants
is
adequately
understood
based
on
sugarcane
metabolism
studies.
The
terminal
residues
of
concern
are
free
and
conjugated
asulam,
sulfanilamide,
N4
­
acetylasulam,
and
N4
­
acetylsulfanilamide
determined
as
a
common
moiety.
Hydroquinone/
quinone
remains
a
chemical
of
toxicological
concern.
However,
hydroquinones
are
naturally
occurring
in
plants.
Relative
to
naturally
occurring
hydroquinones,
hydroquinones
residues
from
asulam
use
on
sugar
is
2
insignificant
and
does
not
increase
risk.
No
new
metabolism
studies
are
needed
on
asulam
on
sugar
to
address
the
hydroquinone
issue
unless
the
registrant
requests
a
new
use
for
asulam.
Monitoring
data
are
not
available
for
this
crop
use.
Therefore,
anticipated
residues
will
be
generated
using
field
trial
data
and
percent
crop
treated
information
from
BEAD.
A
DEEM
Tier
II
dietary
exposure
analysis
will
be
performed.

The
Committee
recognizes
that
further
refinement
to
the
dietary
food
exposure
analyses
may
be
required
as
the
risk
assessment
is
developed.
Therefore,
provided
the
final
dietary
food
exposure
assessment
includes
the
metabolites
of
toxicological
concern
and
does
not
underestimate
the
potential
risk
for
infants
and
children,
the
safety
factor
recommendations
of
this
Committee
stand.

B.
Dietary
Drinking
Water
Exposure
Considerations
(
Correspondence:
J.
Morales
to
C.
Christensen
on
December
3rd,
2001)

The
fate
and
mobility
studies
are
generally
adequate
for
asulam.
Available
fate
data
suggests
the
chemical
is
moderately
persistent
and
mobile.
Degradates
of
toxicological
concern
include
sulfanilamide
and
sulfanilic
acid.
The
magnitude
of
individual
degradates
in
many
fate
studies
cannot
be
determined
from
available
data,
however,
from
an
aged
leaching
column
study,
the
sulfanilamide
degradate
appears
to
be
less
mobile
than
the
parent
asulam.
The
chemical
structures
of
sulfanilamide
and
sulfanilic
acid
are
similar
to
the
structure
of
the
parent
compound.
Runoff
to
surface
water
and
leaching
to
ground
water
are
expected
to
occur
at
relatively
high
levels
from
both
the
parent
and
degradates
of
concern.

The
Environmental
Fate
and
Effects
Division
(
EFED)
has
expressed
some
concerns
for
the
presence
of
asulam
and
its
metabolites
in
surface
and
ground
water.
EFED
assumed
immediate
conversion
of
asulam
upon
application
to
these
degradates
in
their
screening­
level
modeling
with
FIRST
(
surface
water)
and
Sci­
Grow
(
groundwater).
Their
modeling
exercise
further
assumed
these
compounds
to
be
very
persistent
and
very
mobile
in
water.
Therefore,
the
estimated
environmental
concentrations
(
EECs)
for
residues
of
asulam
reported
from
EFED
for
surface
and
ground
water
represent
upper
bound
concentrations
for
residues
of
asulam,
sulfanilamide
and
sulfanilic
acid
in
water.
Because
monitoring
data
exceeded
groundwater
model
estimates,
monitoring
data
were
used
for
ground
water
drinking
water
concentrations.

The
FQPA
Safety
Factor
Committee
recognizes
that
further
refinement
to
the
dietary
water
exposure
analyses
may
be
required
as
the
risk
assessment
is
developed.
Therefore,
provided
the
final
dietary
water
exposure
assessment
includes
all
metabolites
of
toxicological
concern
and
does
not
underestimate
the
potential
risk
for
infants
and
children,
the
safety
factor
recommendations
of
this
Committee
stand.

3
C.
Residential
Exposure
Considerations
There
are
no
residential
uses
registered
for
this
chemical.

SAFETY
FACTOR
RECOMMENDATION
AND
RATIONALE
A.
Recommendation
of
the
Factor
The
Committee
recommended
that
the
FQPA
safety
factor
be
retained
(
10x).

B.
Rationale
for
Retaining
the
FQPA
Safety
Factor
The
Committee
concluded
that
the
safety
factor
is
necessary
when
assessing
the
risk
posed
by
asulam
because:

1.
There
was
evidence
of
quantitative
susceptibility
in
a
two­
generation
reproduction
study
in
the
rat;
and,
2.
HIARC
recommended
the
requirement
for
a
comparative
thyroid
rat
assay
in
adults
and
offspring
and
this
is
considered
a
data
gap
for
asulam.

C.
Application
of
the
Safety
Factor
­
Population
Subgroups:

The
safety
factor
is
required
for
all
population
subgroups
when
assessing
chronic
dietary
exposure
since
the
evidence
for
increase
susceptibility
was
seen
in
the
two­
generation
study,
and
the
results
from
the
comparative
thyroid
assay
may
provide
an
endpoint
for
chronic
risk
assessment.

4
