Document ID: EPA-HQ-OPP-2005-0227-0023
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-03-29T05:00Z

United
States
Prevention,
Pesticides
EPA
738­
R­
00­
009
Environmental
Protection
and
Toxic
Substances
March
2006
Agency
(
7508C)

Report
of
the
Food
Quality
Protection
Act
(
FQPA)
Tolerance
Reassessment
Progress
and
Risk
Management
Decision
(
TRED)
for
Acetochlor
Report
of
the
Food
Quality
Protection
Act
(
FQPA)
Tolerance
Reassessment
Progress
and
Risk
Management
Decision
(
TRED)
for
Acetochlor
Approved
By:

___________________________
Debra
Edwards,
Ph.
D.
Director,
Special
Review
and
Reregistration
Division
___________________________
Date
1
of
9
I.
Regulatory
Determination
The
Federal
Food,
Drug
and
Cosmetic
Act
(
FFDCA),
as
amended
by
FQPA,
requires
EPA
to
reassess
all
the
tolerances
for
registered
chemicals
in
effect
on
the
day
before
enactment
of
the
FQPA
on
August
3,
1996.
In
reassessing
these
tolerances,
the
Agency
must
consider,
among
other
things,
aggregate
risks
from
non­
occupational
sources
of
pesticide
exposure,
whether
there
is
increased
susceptibility
to
infants
and
children,
and
the
cumulative
effects
of
pesticides
with
a
common
mechanism
of
toxicity.
When
a
safety
finding
has
been
made
that
aggregate
risks
are
not
of
concern,
the
tolerances
are
considered
reassessed.
Existing
tolerances
associated
with
acetochlor
must
be
reassessed
in
accordance
with
FFDCA,
as
amended
by
FQPA.
Ecological
and
occupational
assessments
were
originally
conducted
when
acetochlor
was
first
registered
in
1994.
Therefore,
no
further
ecological
or
occupational
assessments
were
conducted
as
part
of
this
Report
of
the
FQPA
Tolerance
Reassessment
Progress
and
Risk
Management
Decision
for
Acetochlor
(
also
referred
to
as
a
TRED).

Acetochlor,
2­
chloro­
N­(
ethoxymethyl)­
N­(
2­
ethyl­
6­
methylphenyl)
acetamide,
is
a
chloroacetanilide
herbicide
used
for
preemergence
control
of
weeds.
It
is
registered
for
use
on
field
corn
and
popcorn,
although
no
tolerances
currently
exist
for
popcorn.
Corn
fields
treated
with
acetochlor
may
later
be
rotated
to
grain
sorghum
(
milo),
soybeans,
wheat,
and
tobacco,
according
to
the
currently
registered
use
pattern.
Residues
in/
on
corn,
popcorn
and
the
rotational
crops
listed
above
were
considered
in
the
acetochlor
dietary
risk
assessment
supporting
the
acetochlor
tolerance
reassessment.

The
Agency's
human
health
and
drinking
water
findings
for
the
pesticide
acetochlor
are
summarized
in
the
following
risk
assessments:
Acetochlor.
Revised
HED
Chapter
of
the
Tolerance
Reassessment
Eligibility
Decision
(
TRED)
Document
dated
March
1,
2006,
and
Drinking
Water
Exposure
Assessment
for
Acetochlor
dated
February
16,
2006.
For
further
details,
please
refer
to
these
risk
assessments
and
other
technical
documents
pertaining
to
the
acetochlor
TRED,
which
are
available
on
the
internet
at
http://
www.
regulations.
gov
and
in
the
public
docket.

EPA
has
determined
that
acetochlor
is
a
member
of
the
chloroacetanilides
group
and
that
the
chloroacetanilides
share
a
common
mechanism
of
toxicity
due
to
their
ability
to
cause
nasal
turbinate
tumors.
The
chloroacetanilides
group
also
includes
alachlor
and
butachlor;
however,
butachlor
was
not
incorporated
into
the
cumulative
assessment
because
there
are
no
U.
S.
registrations
or
established
tolerances.
A
chloroacetanilide
cumulative
assessment
was,
therefore,
conducted
for
acetochlor
and
alachlor
exposures
based
on
a
common
mechanism
of
toxicity.
The
Agency
concludes
in
the
assessment
that
chloroacetanilide
cumulative
risks
are
below
the
Agency's
level
of
concern.
For
more
information
please
refer
to
the
document:
Cumulative
Risk
from
Chloroacetanilide
Pesticides
dated
March
8,
2006,
which
is
also
available
on
the
internet
at
http://
www.
regulations.
gov
and
in
the
public
docket.

The
Agency
has
evaluated
the
human
health
risks
associated
with
all
currently
registered
uses
of
acetochlor
and
has
determined
that
there
is
a
reasonable
certainty
that
no
harm
will
result
from
aggregate
non­
occupational
exposure
to
the
pesticide
chemical
residue.
In
making
this
2
of
9
determination,
EPA
has
considered
dietary
exposure
from
food
and
drinking
water
and
all
other
non­
occupational
sources
of
pesticide
exposure
for
which
there
is
reliable
information.
In
addition,
the
Agency
has
concluded
that
the
cumulative
risks
associated
with
chloroacetanilide
pesticides,
including
acetochlor,
are
below
the
Agency's
level
of
concern.
Therefore,
the
twelve
(
12)
tolerances
established
for
residues
of
acetochlor
in/
on
raw
agricultural
commodities
are
now
considered
reassessed
as
safe
under
section
408(
q)
of
FFDCA,
as
amended
by
FQPA.

The
Agency
is
issuing
this
TRED
document
for
acetochlor
as
announced
in
a
Notice
of
Availability
published
in
the
Federal
Register.
The
Agency
previously
released
the
EPA's
human
health
risk
assessment
and
related
documents
for
acetochlor
for
public
comment
on
November
23,
2005.
The
Agency
considered
all
submitted
comments
in
preparing
this
TRED.
Responses
to
these
comments
are
also
available
on
the
internet
at
http://
www.
regulations.
gov
and
in
the
public
docket.

II.
Tolerance
Reassessment
A.
FQPA
Assessment
Supporting
Tolerance
Reassessment
Decision
The
Agency
has
conducted
risk
assessments
to
ensure
that
the
acetochlor
tolerances
meet
the
safety
standards
established
by
FFDCA,
as
amended
by
FQPA.
These
recent
risk
assessments
for
acetochlor
include
evaluation
of
potential
susceptibility
to
infants
and
children;
and
dietary,
drinking
water,
and
aggregate
risk
from
these
various
exposure
pathways.
EPA
also
considered
potential
cumulative
risks
for
acetochlor
and
other
substances
sharing
a
common
mechanism
of
toxicity.
See
also
Section
II.
B
of
this
document.

EPA
has
determined
that
risk
from
exposure
to
acetochlor,
as
well
as
cumulative
risk
from
total
exposure
to
chloroacetanilides
pesticides,
are
within
their
own
applicable
"
risk
cups".
In
other
words,
EPA
is
able
to
conclude
that
the
tolerances
for
acetochlor
meet
the
FQPA
safety
standards.
In
reaching
this
determination,
the
Agency
has
considered
the
available
information
on
the
potential
sensitivity
of
infants
and
children,
as
well
as
the
chronic
and
acute
food
exposure.
There
are
no
residential
uses
of
acetochlor
nor
are
there
residential
post
application
exposures
expected
from
currently
registered
uses.
Therefore,
an
aggregate
assessment
was
conducted
for
exposures
through
food
and
drinking
water
only.
Results
of
this
aggregate
risk
assessment
indicate
that
the
human
health
risks
from
these
combined
exposures
are
within
acceptable
levels;
that
is,
combined
risks
from
all
exposures
to
acetochlor
"
fit"
within
the
individual
risk
cup
for
this
chemical.
In
addition,
the
Agency
has
concluded
that
the
cumulative
risks
associated
with
chloroacetanilide
pesticides,
including
acetochlor,
are
below
the
Agency's
level
of
concern.
The
Agency's
risk
assessment
conclusions
are
summarized
below.

FQPA
Safety
Factor
Considerations.
The
FFDCA,
as
amended
by
the
FQPA,
directs
the
Agency
to
use
an
additional
tenfold
(
10X)
safety
factor
to
take
into
account
potential
pre­
and
post­
natal
toxicity
and
completeness
of
the
data
with
respect
to
exposure
and
toxicity
to
infants
and
children.
FFDCA
authorizes
the
Agency
to
modify
the
tenfold
safety
factor
only
if
reliable
data
demonstrate
that
the
resulting
level
of
exposure
would
be
safe
for
infants
and
children.
3
of
9
Available
developmental
toxicity
studies
in
two
species
and
three
two­
generation
reproductive
toxicity
studies
in
the
rat
did
not
show
evidence
of
increased
susceptibility
of
the
offspring.
There
are
low
concerns
and
no
residual
uncertainties
with
regard
to
pre­
and/
or
postnatal
toxicity.
However
based
on
evidence
of
neurotoxicity,
which
was
observed
in
studies
in
the
dog
and
in
the
rat
including
frank
neuropathology
in
a
chronic
dog
study,
the
Agency
is
requiring
that
a
developmental
neurotoxicity
(
DNT)
study
be
submitted
by
the
registrant.
Pending
submission
and
Agency
review
of
this
study,
an
FQPA
safety
factor
of
10X
was
retained
for
deriving
the
acute
dietary
reference
dose
for
acetochlor
to
account
for
the
absence
of
the
DNT
study.
A
10X
FQPA
safety
factor
was
not
used
in
calculation
of
the
chronic
dietary
reference
dose
because
the
results
of
the
DNT
are
not
expected
to
affect
this
risk
assessment.

Dietary
Risks
from
Food
and
Drinking
Water.
Acute,
chronic,
and
cancer
dietary
(
food
and
drinking
water)
risk
assessments
were
conducted
that
considered
all
registered
acetochlor
uses
(
corn
and
rotational
crops)
using
the
Dietary
Exposure
Evaluation
Model
software
with
the
Food
Commodity
Intake
Database
(
DEEM­
FCID),
which
uses
food
consumption
data
from
the
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII)
from
1994­
1996
and
1998.
Although
there
is
no
existing
tolerance
for
popcorn,
a
dietary
risk
assessment
that
included
popcorn
was
completed
since
it
is
a
registered
use.
Field
corn
field
trial
data
were
translated
to
popcorn
for
this
assessment.
The
acute,
chronic,
and
cancer
dietary
(
food)
exposure
assessment
incorporated
tolerance
or
proposed
tolerance
level
residues
for
all
crops
and
percent
crop
treated
data
provided
by
the
Acetochlor
Registration
Partnership
(
ARP).
Processing
data
were
available
for
numerous
commodities
and
incorporated
into
the
assessment.
See
also
Acetochlor.
Acute,
Chronic,
and
Cancer
Dietary
Exposure
Assessments
for
the
Tolerance
Reassessment
Eligibility
Decision
(
TRED)
Document
dated
June
30,
2005
for
detailed
information.

The
dietary
risk
assessment
included
residues
of
the
parent,
acetochlor,
and
the
metabolites
2­
ethyl­
6­
methylaniline
(
EMA)
and
2­
hydroxyethyl­
6­
methylaniline
(
HEMA)
in/
on
the
primary
crops,
corn
and
popcorn.
In
addition
to
EMA
and
HEMA,
the
dietary
risk
assessment
also
included
residues
of
the
metabolite
hydroxymethyl
ethyl
aniline
(
HMEA)
in/
on
rotational
crops
(
i.
e.,
crops
grown
in
fields
previously
treated
with
acetochlor).
These
metabolites,
EMA,
HEMA,
HMEA,
are
only
found
in
plants,
thus,
they
were
not
included
in
the
drinking
water
assessment.
Refer
to
the
Environmental
Degradates
section
below
for
additional
information
about
metabolites
found
in
drinking
water.

EPA
obtained
drinking
water
residues
from
the
Acetochlor
Registration
Partnership
(
ARP)
acetochlor
water
monitoring
program.
The
ARP
monitored
a
total
of
175
Community
Water
Supplies
(
CWSs)
in
nine
mid­
western
and
three
Mid­
Atlantic
States
for
the
acetochlor
surface
water
monitoring
program.
The
selection
process
was
designed
to
include
a
wide
array
of
CWSs
with
watersheds
in
areas
of
corn
production,
with
an
emphasis
on
including
worst­
case
watersheds
i.
e.,
smaller
watersheds
(
not
on
the
Great
Lakes
and
continental
rivers)
in
areas
of
high
corn
production.
Residues
of
acetochlor
from
this
monitoring
program
were
incorporated
directly
into
the
DEEM­
FCID
model.
EPA
considers
both
acute
(
one
day)
and
chronic
(
lifetime)
drinking
water
risks
and
exposure
to
pesticides
through
contamination
of
surface
and
ground
4
of
9
water
sources.
The
acetochlor
risk
estimates
for
acute,
chronic,
and
cancer
dietary
exposure
reflect
combined
food
and
drinking
water
exposure.
For
detailed
information
see
the
document
titled,
Revised
Drinking
Water
Exposure
Assessment
for
Acetochlor
dated
February
16,
2006.

The
population
adjusted
dose
(
PAD)
is
the
dose
predicted
to
result
in
no
unreasonable
adverse
effects
to
any
human
subpopulation,
including
sensitive
members
of
such
subpopulation.
Estimated
dietary
risks
less
than
100%
of
the
PAD
are
not
of
concern
to
the
Agency.
The
acute
dietary
risk
assessment
showed
that
for
all
registered
commodities,
the
acute
dietary
risk
estimates
(
food
and
drinking
water)
do
not
exceed
the
Agency's
level
of
concern
at
the
99.9th
percentile
of
exposure
for
all
populations.
The
general
U.
S.
population
comprises
2%
of
the
acute
population
adjusted
dose
(
aPAD),
with
the
highest
exposed
population
subgroup
being
infants
less
than
1
year
old
at
6%
of
the
aPAD.
The
aPAD
is
the
dose
at
which
a
person
could
be
exposed
on
any
given
day
with
no
adverse
health
effects,
and
was
derived
from
an
acute
rat
neurotoxicity
study
in
which
decreased
motor
activity
in
females
was
observed.

EPA's
chronic
dietary
risk
assessment
indicates
that
dietary
risk
from
acetochlor
residues
in
food
and
drinking
water
are
low
and
also
not
of
concern.
The
resulting
chronic
dietary
exposure
estimates
using
the
DEEM­
FCID
model
were
less
than
1%
of
the
chronic
population
adjusted
(
cPAD)
for
the
U.
S.
general
population
and
all
population
subgroups
including
the
most
highly
exposed
population
subgroup,
all
infants
(<
1
years
old).
The
cPAD
is
the
dose
at
which
a
person
could
be
exposed
over
the
course
of
a
lifetime
with
no
adverse
health
effects,
and
was
derived
from
a
chronic
oral
toxicity
study
in
beagle
dogs
in
which
increased
salivation
and
histopathology
in
the
testes,
kidney
and
liver
were
observed.

The
Agency
classified
acetochlor
as
"
likely
to
be
carcinogenic
to
humans"
based
on
increased
incidence
of
lung
tumors
in
male
and
female
mice,
histiocytic
sarcoma
in
female
mice
and
nasal
epithelial
tumors,
and
thyroid
follicular
cell
adenomas
in
male
and
female
rats.
A
nonmutagenic
(
with
threshold)
mode
of
action
was
established
for
the
nasal
and
thyroid
tumors;
however,
no
mode
of
action
was
established
for
the
other
observed
tumors.
In
the
absence
of
supporting
mechanistic
data
for
the
formation
of
lung
tumors
and
histiocytic
sarcomas
in
mice,
a
linear
low­
dose
extrapolation
was
used
to
estimate
cancer
risk
for
those
tumors.
The
cancer
dietary
exposure
assessment
incorporated
tolerance
or
proposed
tolerance
level
residues
for
all
crops
and
percent
crop
treated
data
provided
by
the
ARP,
assuming
consumption
of
those
foods
over
a
70
year
lifetime.
Processing
data
were
available
for
all
commodities
and
incorporated
into
the
assessment.
The
assessment
also
included
the
overall
multi­
year
time
weighted
annualized
mean
surface
water
concentration
generated
from
the
ARP
acetochlor
water
monitoring
program.
The
chronic
exposure
value
was
multiplied
by
a
linear
low­
dose
response
factor
(
Q1*)
of
3.27
x
10­
2
based
on
animal
studies
to
determine
the
lifetime
cancer
risk
estimate.
The
estimated
dietary
(
food
and
drinking
water)
cancer
risk
for
the
general
U.
S.
population
was
8.40
x
10­
7,
and
was
below
the
Agency's
level
of
concern
(
1
x
10­
6).
Therefore,
no
mitigation
measures
are
necessary
to
address
dietary
risks
from
food
and
drinking
water.
5
of
9
Residential
Risks.
Currently
there
are
no
registered
residential
uses
nor
potential
residential
post­
application
exposures
for
acetochlor,
thus
no
residential
exposure
assessment
was
conducted.

Aggregate
Risk.
In
examining
aggregate
exposure,
EPA
takes
into
account
the
available
and
reliable
information
concerning
exposures
from
pesticide
residues
in
food
and
other
exposures
including
drinking
water
and
non­
occupational
exposures,
e.
g.,
exposure
to
pesticides
used
in
and
around
the
home
(
residential).
Risk
assessments
for
aggregate
exposure
consider
short­,
intermediate­
and
long­
term
(
chronic)
exposure
scenarios
considering
the
toxic
effects
which
would
likely
be
associated
with
each
exposure
duration.
Since
there
are
no
residential
uses
of
acetochlor,
the
considerations
for
aggregate
exposure
are
those
from
food
and
drinking
water
only.
As
discussed
above,
the
results
of
the
acute,
chronic
and
cancer
aggregate
assessments
indicate
that
the
combined
exposure
to
acetochlor
from
food
and
drinking
water
is
below
the
Agency's
level
of
concern.
Therefore,
no
mitigation
measures
are
necessary
to
address
aggregate
risks.

Environmental
Degradates.
The
drinking
water
assessment
was
conducted
using
the
parent
acetochlor
as
the
residue
of
concern.
However,
there
are
two
degradates
of
acetochlor
which
may
be
found
in
drinking
water.
These
degradates,
acetochlor
sulfonic
acid
(
ESA)
and
acetochlor
oxanilic
acid
(
OXA),
were
not
included
in
the
water
risk
assessment
based
on
comparison
of
the
available
toxicity
data
for
acetochlor
and
the
ESA
and
OXA
degradates
and
structure­
activity
relationships
which
showed
that
neither
ESA
nor
OXA
degradates
are
likely
to
be
carcinogenic
and
that
both
are
significantly
less
toxic
than
the
parent
acetochlor.

However,
extensive
surface
and
ground
water
monitoring
data
for
acetochlor
and
its
two
degradates
have
been
collected
as
required
by
the
Agency
under
the
conditional
registration
of
acetochlor.
These
monitoring
studies
showed
that
both
the
ESA
and
OXA
degradates
have
been
detected
in
water
samples
(
both
groundwater
and
surface
water).
Concentrations
of
the
degradates
in
surface
water
were
in
the
same
order
of
magnitude
as
acetochlor
while
groundwater
concentrations
of
the
degradates
were
significantly
higher
than
those
of
the
parent.
Given
the
potential
for
relatively
high
levels
of
degradates
in
drinking
water,
worst­
case
margin­
of­
exposure
(
MOE)
calculations
were
conducted
to
estimate
potential
drinking
water
risks
for
the
two
degradates.
MOEs
ranged
from
>
21,000
to
122,000
for
ESA
and
45,000
to
264,000
for
OXA
and,
therefore,
were
below
the
Agency's
level
of
concern.

B.
Cumulative
Assessment
As
previously
stated,
acetochlor
is
a
member
of
the
chloroacetanilides
group
which
shares
a
common
mechanism
of
toxicity
due
to
the
members'
ability
to
cause
nasal
turbinate
tumors.
The
chloroacetanilide
group
also
includes
the
chemicals
alachlor
and
butachlor.
This
determination
can
be
found
in
the
chloroacetanilides
common
mechanism
group
(
CMG)
decision
document
published
in
2001
entitled
"
The
Grouping
of
a
Series
of
Chloroacetanilide
Pesticides
Based
on
a
Common
Mechanism
of
Toxicity"
(
http://
www.
epa.
gov/
oppfod01/
cb/
csb_
page/
updates/
commechs.
htm).
Butachlor,
however,
has
no
registered
uses
or
tolerances
and
has
been
excluded
from
the
risk
6
of
9
assessment.
Thus,
the
Common
Assessment
Group
(
CAG),
on
which
the
risk
assessment
was
conducted,
consists
of
acetochlor
and
alachlor
only.

Development
of
nasal
olfactory
epithelium
tumors
in
rats
has
been
attributed
to
a
non­
linear,
non­
mutagenic
mode
of
action.
Thus,
as
per
the
2005
EPA
Cancer
Guidelines,
the
Agency
used
a
margin­
of­
exposure
(
MOE)
calculation
for
the
cumulative
risk
assessment
as
one
would
do
for
a
threshold
noncancer
toxicity
risk
assessment.
Because
the
threshold
approach
was
used
for
assessing
the
risks,
uncertainty
factors
(
UFs)
of
10x
(
interspecies)
and
10x
(
intraspecies)
were
used.
Further,
since
there
is
no
evidence
of
potential
pre­
and
post­
natal
susceptibility,
the
FQPA
safety
factor
was
reduced
to
1x.
Therefore,
MOEs
above
100
were
considered
to
be
below
the
Agency's
level
of
concern
(
LOC).

The
chloroacetanilide
cumulative
risk
assessment
involved
only
two
pathways
of
exposure
(
food
and
drinking
water)
via
the
oral
route
of
exposure.
Because
the
nasal
olfactory
epithelium
tumors
are
a
systemic
chronic
endpoint,
only
a
chronic
dietary
analysis
was
conducted
using
the
Dietary
Exposure
Evaluation
Model
software
with
the
Food
Commodity
Intake
Database
(
DEEM­
FCIDTM,
Version
2.03).
Results
of
the
DEEM­
FCIDTM
analysis
produced
cumulated
MOEs
greater
than
13,000
for
all
populations.
Therefore,
the
cumulated
MOE
values
estimated
for
the
subject
CAG
are
below
the
Agency's
level
of
concern.
Because
these
cumulative
MOE
values
were
obtained
using
high­
end
exposures,
they
are
considered
to
be
protective.
More
detailed
information
related
to
the
chloroacetanilide
cumulative
risk
assessment
can
be
found
in
the
document:
Cumulative
Risks
from
Chloroacetanilide
Pesticides
dated
March
8,
2006,
which
is
available
on
the
internet
at
http://
www.
regulations.
gov
and
in
the
public
docket.

C.
Endocrine
Disruptor
Effects
EPA
is
required
under
the
FFDCA,
as
amended
by
FQPA,
to
develop
a
screening
program
to
determine
whether
certain
substances
(
including
all
pesticide
active
and
other
ingredients)
"
may
have
an
effect
in
humans
that
is
similar
to
an
effect
produced
by
a
naturally
occurring
estrogen,
or
other
such
endocrine
effects
as
the
Administrator
may
designate."
Following
recommendations
of
its
Endocrine
Disruptor
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
a
scientific
basis
for
including,
as
part
of
the
program,
the
androgen
and
thyroid
hormone
systems,
in
addition
to
the
estrogen
hormone
system.
EPA
also
adopted
EDSTAC's
recommendation
that
the
Program
include
evaluations
of
potential
effects
in
wildlife.
For
pesticide
chemicals,
EPA
will
use
FIFRA
and,
to
the
extent
that
effects
in
wildlife
may
help
determine
whether
a
substance
may
have
an
effect
in
humans,
FFDCA
authority
to
require
the
wildlife
evaluations.
As
the
science
develops
and
resources
allow,
screening
of
additional
hormone
systems
may
be
added
to
the
Endocrine
Disruptor
Screening
Program
(
EDSP).

Studies
in
the
rat
evaluating
thyroid
and
liver
effects
following
dietary
administration
of
acetochlor
at
various
dose
levels
indicate
that
acetochlor
may
disrupt
thyroid­
pituitary
homeostasis
via
increased
hepatic
UDPGH­
mediated
increased
clearance
of
the
thyroid
hormone
thyroxine
(
T4).
Slightly
increased
incidence
of
thyroid
follicular
cell
tumors
have
been
observed
in
rat
two­
year
bioassay
studies
at
higher
dose
levels.
Although
thyroid
follicular
cell
tumors
were
considered
to
be
related
to
treatment,
they
were
not
considered
as
part
of
the
cancer
7
of
9
quantification,
due
to
relatively
low
incidence
and
evidence
for
disruption
of
thyroid
hormonal
homeostasis
as
the
mode
of
action.
Structure­
activity
relationship
data
on
the
related
chloroacetanilide
herbicides
alachlor
and
butachlor
support
this
conclusion.
The
available
data
do
not
indicate
that
acetochlor
disrupts
androgen
or
estrogen
hormone
systems.

When
additional
appropriate
screening
and/
or
testing
protocols
being
considered
under
the
Agency's
EDSP
have
been
developed,
acetochlor
may
be
subjected
to
further
screening
and/
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.

D.
Tolerance
Summary
The
current
tolerance
expression
for
residues
of
acetochlor
resulting
from
direct
application
to
primary
crops
is
adequate.
The
Agency
has
determined
that
the
tolerance
expression
for
residues
in/
on
corn,
popcorn,
and
rotational
crop
commodities
should
include
only
acetochlor
and
its
metabolites
containing
the
2­
ethyl­
6­
methylaniline
(
EMA)
and
2­
hydroxyethyl­
6­
methylaniline
(
HEMA)
moiety,
expressed
in
acetochlor
equivalents.
A
summary
of
acetochlor
tolerance
reassessments
is
presented
in
Table
1.

Tolerances
Listed
Under
40
CFR
§
180.470:

Adequate
residue
data
have
been
submitted
to
reassess
the
established
tolerances
for
corn
commodities.
The
available
field
trial
data
indicate
that
the
current
tolerances
on
corn
grain
and
stover
are
adequate,
but
the
tolerance
on
corn
forage
should
be
increased
to
3.0
ppm
based
on
data
from
the
early
postemergence
use.
Adequate
field
rotational
crop
trials
are
also
available
to
support
the
currently
established
tolerances
on
commodities
of
rotational
sorghum,
and
wheat.
The
tolerance
on
soybean
grain
should
be
increased
to
0.1
ppm
based
on
the
submitted
rotational
crop
data.

As
the
tolerances
on
field
corn
commodities
are
for
the
direct
application
to
a
primary
crop,
these
general
tolerances
on
corn
will
be
reassigned
to
40
CFR
§
180.470(
a).
Likewise,
tolerances
on
sorghum,
soybeans,
and
wheat
commodities
are
for
inadvertent
residues
on
rotational
crops;
therefore,
these
tolerances
will
be
reassigned
to
40
CFR
§
180.470(
d).

The
40CFR
§
180.470
should
be
revised
and
separated
into
subparts
(
a)
through
(
d).
Subpart
(
a)
should
contain
tolerances
resulting
from
the
direct
application
of
acetochlor
to
a
primary
crop;
(
b)
Section
18
emergency
exemptions,
(
c)
tolerances
with
regional
registrations,
and
(
d)
tolerances
resulting
from
indirect
or
inadvertent
residues.

Based
on
the
residue
data
for
currently
registered
uses
and
rotational
crops,
tolerances
for
livestock
commodities
are
not
required
at
the
present
time.
8
of
9
Tolerances
Needed
Under
40
CFR
§
180.470(
a):

Acetochlor
is
registered
for
use
on
popcorn;
however,
there
are
no
existing
tolerances
associated
with
this
use.
Adequate
data
submitted
by
the
ARP
are
available
and
a
dietary
assessment
was
conducted
which
included
the
use
of
acetochlor
on
popcorn.
Information
is
being
reviewed
to
determine
whether
the
tolerance
can
be
established,
and
the
Agency
will
address
this
issue
when
it
considers
pending
new
use
petitions.

Tolerances
Needed
Under
40
CFR
§
180.470(
d):

The
available
rotational
crop
field
trial
data
on
wheat
forage
and
straw
indicate
that
residues
are
also
likely
to
occur
on
wheat
hay.
A
tolerance
for
wheat
hay
can
be
set
using
the
residue
data
for
wheat
forage
and
adjusting
for
the
differences
in
dry
weight
between
the
two
commodities.
Based
on
maximum
residues
of
0.457
ppm
in/
on
wheat
forage
(
25%
dry
wt.),
maximum
expected
residues
in/
on
wheat
hay
(
88%
dry
wt.)
would
be
1.61
ppm.
Therefore,
a
permanent
tolerance
of
2.0
ppm
needs
to
be
established
for
wheat
hay.
The
addition
of
this
tolerance
will
not
change
the
current
calculated
maximum
dietary
burden
for
cattle.

Table
1.
Tolerance
Reassessment
Summary
for
Acetochlor
Commodity
Current
Tolerance
(
ppm)
Range
of
Residues
(
ppm)
Tolerance
Reassessment
(
ppm)
Comment/[
Correct
Commodity
Definition]

Tolerances
Listed
Under
40
CFR
§
180.470
Corn,
field,
forage
1.0
<
0.05­
2.52
3.0
Corn,
field,
grain
0.05
<
0.05
0.05
Corn,
field,
stover
1.5
<
0.05­
1.08
1.5
Tolerances
on
corn
commodities
should
be
reassigned
to
§
180.470(
a)
as
these
tolerances
are
for
the
direct
use
on
corn.

Sorghum,
forage
0.1
<
0.02­
0.093
0.1
Sorghum,
grain
0.02
<
0.02
0.02
Sorghum,
grain,
stover
0.1
<
0.02­
0.068
0.1
Soybean,
forage
0.7
<
0.2­
0.648
0.7
Soybean,
grain
0.02
<
0.02­
0.101
0.1
Soybean,
hay
1.0
<
0.024­
1.064
1.0
Wheat,
forage
0.5
<
0.02­
0.457
0.5
Wheat,
grain
0.02
<
0.02
0.02
Wheat,
straw
0.1
<
0.02­
0.104
0.1
Tolerances
on
sorghum,
soybean,
and
wheat
commodities
should
be
reassigned
to
§
180.470(
d)
as
these
are
tolerances
for
inadvertent
residues
in/
on
rotational
crops.

The
correct
commodity
definition
for
Sorghum,
grain
is
Sorghum,
grain,
grain
and
for
Soybean,
grain
is
Soybean,
seed.

Tolerances
Needed
under
40
CFR
§
180.470(
a)

Corn,
pop,
grain
0.5
<
0.05
0.05
A
permanent
tolerance
should
be
set
at
0.05
ppm
based
on
maximum
residues
in
field
corn
grain.

1.5
<
0.05­
1.08
1.5
A
permanent
tolerance
should
be
set
9
of
9
Table
1.
Tolerance
Reassessment
Summary
for
Acetochlor
Commodity
Current
Tolerance
(
ppm)
Range
of
Residues
(
ppm)
Tolerance
Reassessment
(
ppm)
Comment/[
Correct
Commodity
Definition]

Corn,
pop,
stover
at
0.05
ppm
based
on
maximum
residues
in
field
corn
stover.

Tolerances
Needed
under
40
CFR
§
180.470(
d)

Wheat,
hay
None
1.611
2.0
A
permanent
tolerance
should
be
set
at
2.0
ppm
based
on
maximum
residues
in
wheat
forage
corrected
for
moisture
content.

1.
Maximum
expected
residues
in
wheat
hay
(
88%
dry
wt.),
based
on
maximum
residues
of
0.457
ppm
in
wheat
forage
(
25%
dry
wt.).

III.
Data
Requirements
There
are
data
that
must
be
submitted
to
support
the
continuing
registration
of
acetochlor.
These
data
are
not
expected
to
change
the
regulatory
conclusions
for
acetochlor
described
in
this
document.
A
generic
data
call­
in
(
DCI)
will
be
issued
and
will
require
development
and
submission
of
these
listed
data:

Toxicology
870.6300
A
developmental
neurotoxicity
study
is
required.

870.6200
Validation
studies
(
positive
controls)
are
required
for
the
rat
neurotoxicity
studies.