1
Trifluralin
Risk
Assessment
Overview
(
August
30,
2004)

Introduction
This
document
summarizes
EPA's
human
health
and
environmental
fate
risk
finding
for
the
preemergence
herbicide
trifluralin.
These
findings
are
presented
fully
in
the
HED
human
health
risk
assessment
document
"
Trifluralin:
Human
Health
Risk
Assessment"
dated
May
7,
2004;
and
the
EFED
water
assessment
document
"
Trifluralin
­
Drinking
Water
Assessment
for
Tolerance
Reassessment
Eligibility
Decision",
dated
December
3,
2003.

The
purpose
of
this
overview
is
to
assist
the
reader
in
understanding
the
conclusions
reached
in
the
risk
assessments
by
identifying
the
key
features
and
findings
of
each.

Use
Profile
$
Herbicide:
Trifluralin
is
a
selective,
pre­
emergence,
dinitroaniline
herbicide
primarily
used
in
soybeans
and
cotton.
Additionally,
trifluralin
is
used
on
residential
lawns,
landscape
ornamentals,
trees,
and
vegetable
gardens
and
is
also
marketed
for
use
by
professional
applicators
on
residential
turf,
on
golf
courses,
other
turf
such
as
recreational/
commercial
areas,
and
on
ornamental
plantings.
Important
markets
for
trifluralin
usage
include:
soybeans,
cotton,
wheat,
alfalfa,
sunflowers,
and
dry
beans/
peas.
However,
use
of
this
chemical
is
also
important
for
minor
crops
such
as
peas,
okra,
sunflower,
asparagus,
peanuts,
vegetables,
tomatoes
and
beans.

$
Targeted
Pest:
Registered
products
containing
trifluralin
are
intended
for
the
control
of
annual
grasses
and
certain
broadleaf
weeds.

$
Formulations:
Trifluralin
is
formulated
as
a
dust,
emulsifiable
concentrate,
granular,
emulsifiable
concentrate/
liquid,
and
soluble
concentrate.
Trifluralin
end­
use
products
for
food
and
feed
crops
include
emulsifiable
concentrates
(
EC,
36.4,
50.8%
ai)
and
a
granular
formulation,
(
G,
10%),(
EC,
43%
ai).
For
residential
and
other
non­
agricultural
uses,
trifluralin
is
formulated
as
a
granular
(
G,
0.17
­
2.0%
ai),
which
is
the
only
formulation
used
on
turf
for
this
usage,
and
an
emulsifiable
concentrate
liquid
(
EC,
43%
ai).
2
$
Method
of
Application:
Currently,
trifluralin
may
be
applied:
dormant,
semi­
dormant,
preplant
pre­
transplant,
pre­
emergence,
post­
emergence,
lay­
by
or
post­
harvest
(
as
a
soil
incorporated
treatment),
liquid
sprays
of
water
or
liquid
fertilizer,
or
impregnated
on
dry
bulk
fertilizer
or
clay
granules.
Trifluralin
is
generally
applied
once
per
growing
season
on
all
registered
crops
and
sites.
However,
there
are
exceptions
for
sugarcane
and
cotton.
Additionally,
trifluralin
is
soil
incorporated
into
the
top
2­
3
inches
of
soil
within
24
hours
of
application
and
can
be
applied
via
chemigation
on:
alfalfa,
field
corn,
cotton,
grain
sorghum
(
milo),
potatoes,
tree
and
vine
crops,
and
soybeans.
The
maximum
amount
of
trifluralin
per
acre
per
year
that
can
be
applied
depends
on
the
site
of
use.
For
homeowner
use,
trifluralin
may
be
in
a
granular
or
liquid
form,
and
applied
via
belly
grinder,
push­
type
spreader,
shaker
can
(
by
hand),
hose­
end
sprayer,
low
pressure
handwand,
backpack
sprayer,
and
impregnated
fabric
squares
to
soil
at
various
rates
from
3
lbs
ai/
A
on
turf,
to
20
lbs
ai/
A
on
ornamental
beds.

$
Use
Summary:
The
top
six
uses
of
trifluralin
include
soybeans,
cotton
(
75%
of
the
volume
is
applied
to
soybeans
and
cotton),
wheat,
alfalfa,
sunflowers,
and
dry
beans/
peas,
and
accounts
for
93%
of
total
trifluralin
ai
applied
in
the
US.
However,
turf
uses
predominate
with
approximately
75%
of
use
on
turf
occurring
in
the
North,
20%
in
the
South,
and
5%
used
elsewhere.
Based
on
1997­
2001
data,
the
Agency
estimates
that
approximately
18
million
pounds
of
trifluralin
ai
is
used
per
year
for
agricultural
production
in
the
United
States.
The
majority
of
the
agriculture
use
is
in
the
Midwest,
High
Plains,
Mid­
South
and
Central
Valley
regions.
Additionally,
more
than
50%
of
the
acreage
planted
in
tomatoes
and
carrots
is
treated
with
trifluralin.

The
label
rate
for
agricultural
uses
is
1
to
2
lbs
ai/
acre,
with
a
maximum
rate
of
4
lbs
ai/
acre
on
sugarcane,
whereby
the
registrant
reports
a
typical
use
rate
of
1lb
ai/
acre,
or
less.

$
Technical
Registrant:
Dow
AgroSciences
EPA
does
not
have,
at
this
time,
available
data
to
determine
whether
trifluralin
has
a
common
mechanism
of
toxicity
with
other
substances.
Unlike
other
pesticides
for
which
EPA
has
followed
a
cumulative
risk
approach
based
on
a
common
mechanism
of
toxicity,
EPA
has
not
made
a
common
mechanism
of
toxicity
finding
as
to
trifluralin
and
any
other
substances.
For
purposes
of
this
tolerance
action,
therefore,
EPA
has
not
assumed
that
trifluralin
has
a
common
mechanism
of
toxicity
with
other
substances.

Hazard
Characterization
The
Trifluralin
toxicology
database
is
sufficient
for
tolerance
reassessment
and
adequate
for
Food
Quality
Protection
Act
(
FQPA)
consideration.
The
Agency
determined
that
since
the
dose
3
response
was
well
characterized,
the
developmental
effects
were
only
seen
in
the
presence
of
maternal
toxicity,
and
clear
No
Observable
Adverse
Effect
Levels
(
NOAELs)
were
established
for
developmental
and
maternal
toxicities,
thus
the
concern
for
increased
susceptibility
for
children
was
low.

The
FQPA
Safety
Factor
recommendation
by
the
Hazard
Identification
Assessment
and
Review
Committee
(
HIARC)
assumed
that
the
exposure
databases
(
food,
drinking
water,
and
residential)
are
complete
and
the
risk
assessment
for
each
exposure
scenario
includes
all
metabolites
and/
or
degradates
of
concern,
and
the
assessment
does
not
underestimate
the
potential
risk
for
infants
and
children.
Upon
review
of
the
trifluralin
toxicity
data,
the
HIARC
selected
the
appropriate
studies,
endpoints,
and
dose
levels
for
human
health
risk
assessment
(
see
Table
1
below).

Table
1:
SUMMARY
OF
TOXICOLOGY
ENDPOINT
SELECTION
Summary
of
Toxicological
Dose
and
Endpoints
for
Trifluralin
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
FQPA
SF*
Target
MOE
Study
and
Toxicological
Effects
Acute
Dietary
(
Females
13­
50
years
of
age)
NOAEL
=
100
mg/
kg/
day
UF
=
100
Acute
RfD
=
1.0
mg/
kg/
day
FQPA
SF
=
1
aPAD
=
1.0
mg/
kg/
day
Developmental
Toxicity
Study
­
Rat
LOAEL
=
500
mg/
kg/
day
based
on
increased
total
litter
resorptions.

Acute
Dietary
(
All
populations)
No
appropriate
single
dose
endpoint
was
selected
for
all
populations
except
Females
13­
50.

Chronic
Dietary
(
All
populations)
NOAEL=
2.4
mg/
kg/
day
UF
=
100
Chronic
RfD
=
0.024
mg/
kg/
day
FQPA
SF
=
1
cPAD
=
0.024
mg/
kg/
day
Chronic
Toxicity
(
capsule)
­
Dog
LOAEL
=
40
mg/
kg/
day
Short­
Term
Incidental
Oral
(
1­
30
days)
NOAEL=
10
mg/
kg/
day
MOE
=
100
Two­
generation
Reproduction
Study
­
Rat
LOAEL
=
32.5
mg/
kg/
day
based
on
decreased
pup
weights
in
both
generations
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
FQPA
SF*
Target
MOE
Study
and
Toxicological
Effects
4
Intermediate­
Term
Incidental
Oral,
Dermal
and
Inhalation
(
1­
6
months)
NOAEL=
10
mg/
kg/
day
(
Dermal
absorption
rate
=
3
%

(
Inhalation
absorption
rate
=
100
%)
MOE
=
100
Special
Urinalysis
Study
­
Rat
LOAEL
=
40
mg/
kg/
day
Short­
Term
Dermal
(
1
to
30
days)
No
quantification
required
since
there
was
no
systemic
toxicity
at
the
limit
dose
in
the
dermal
toxicity
study.
There
are
no
developmental
toxicity
concerns.

Long­
Term
Dermal
(>
6
months)
Oral
study
NOAEL=
2.4
mg/
kg/
day
(
dermal
absorption
rate
=
3
%
when
appropriate)

(
Inhalation
absorption
rate
=
100
%)
Residential
MOE
=
100
Chronic
Toxicity
(
capsule)
­
Dog
LOAEL
=
40
mg/
kg/
day
Short­
Term
Inhalation
(
1
to
30
days)
Inhalation
study
NOAEL=
81
mg/
kg/
day
Residential
MOE
=
100
30­
Day
Inhalation
Study
­
Rat
LOAEL
=
270
mg/
kg/
day
Cancer
(
oral,
dermal,
inhalation)
Q1*
=
5.8
X
10­
3
(
mg/
kg/
day)­
1
Group
C
("
Possible"
Human
Carcinogen)

UF
=
uncertainty
factor,
FQPA
SF
=
FQPA
safety
factor,
NOAL
=
no
observed
adverse
effect
level,
LOAEL
=
lowest
observed
adverse
effect
level,
PAD
=
population
adjusted
dose
(
a
=
acute,
c
=
chronic)
RfD
=
reference
dose,
MOE
=
margin
of
exposure,
NA
=
Not
Applicable
NOTE:
Since
a
toxicological
endpoint,
based
on
dermal
exposure,
was
not
selected
for
trifluralin,
only
post­
application
incidental
oral
ingestion
(
i.
e.,
soil,
granule,
and
hand­
to­
mouth
ingestion)
exposures
to
children
were
calculated.

The
Agency
concluded
that
the
FQPA
Safety
Factor
should
be
removed
(
equivalent
to
a
1x
Safety
Factor)
based
on
a
conclusion
of
no
concern
for
qualitative
susceptibility
seen
for
pre­
and
postnatal
toxicities.
However,
the
Agency
remains
concerned
about
dermal
sensitization
reactions
to
adults
and
children
who
are
exposed
to
trifluralin
in
residential
settings
and
recommends
for
labeling
to
this
effect,
on
all
products.
5
Human
Health
Risk
Assessment
Acute
Dietary
(
Food)
Risk
Acute
dietary
risk
is
calculated
considering
the
toxicity
of
a
chemical,
what
is
eaten
by
individuals
in
one
day
and
residue
values
for
various
foods.
A
risk
estimate
that
is
less
than
100%
of
the
acute
Population
Adjusted
Dose
(
aPAD)
(
the
dose
at
which
an
individual
could
be
exposed
on
any
given
day
and
no
adverse
health
effects
would
be
expected)
does
not
exceed
the
Agency's
risk
concern.

An
acute
Population
Adjusted
Dose
(
aPAD)
of
1.0
mg/
kg/
day
was
established
for
females
of
child­
bearing
age
based
on
the
No
Observable
Adverse
Effect
Level
(
NOAEL)
of
100
mg/
kg/
day
observed
in
the
rat
developmental
study.
The
Dietary
Exposure
Evaluation
Model
(
DEEM
 
)
analysis
evaluated
the
individual
food
consumption
as
reported
by
respondents
in
the
USDA
1994­
1996
and
1998
Nationwide
Continuing
Surveys
of
Food
Intake
by
Individuals
(
CSFII)
and
accumulated
exposure
to
the
chemical
for
each
commodity.
Additionally,
acute
risks
were
also
estimated
using
the
Lifeline
model
(
version
2.0).
Lifeline
converts
the
raw
agricultural
commodity
(
RAC)
residues
into
food
residues
by
randomly
selecting
a
RAC
residue
value
from
the
user
defined
residue
distribution
(
created
from
the
residue,
percent
crop
treated,
and
processing
factors
data),
and
calculating
a
net
residue
for
that
food
based
on
the
ingredient's
mass
contribution
to
that
food
item.
The
Lifeline
model
estimated
acute
exposure
based
on
the
acute
1­
day
dietary
dose
drawn
randomly
from
an
age­
specific
seasonal
exposure
profile
of
1000
individuals.

An
acute
dietary
assessment
was
not
conducted
for
the
general
U.
S.
population
or
infants
and
children
because
there
was
no
appropriate
single
dose
endpoint
for
this
population
sub­
group.
The
acute
dietary
risk
estimates
are
below
the
Agency's
level
of
concern
(<
100%
aPAD)
at
the
99.9th
exposure
percentile
for
the
females
13
­
49
years
of
age
(<
1%
aPAD),
the
population
subgroup
of
concern.
Results
of
the
Lifeline
analysis
are
fully
consistent
with
DEEM­
FCID
results
(
See
Table
2
below).

Table
2.
Results
of
Acute
Dietary
Exposure
Analysis
Using
both
DEEM
FCID
and
Lifeline
Softwares
Population
Subgroup
aPAD
(
mg/
kg/
day)
Model
99.9th
Percentile
Exposure
(
mg/
kg/
day)
%
aPAD
Females
13­
49
yrs
1
DEEM­
FCID
0.000262
0.03
Lifeline
0.000311
0.03
6
Chronic
and
Cancer
Dietary
(
Food
and
Water)
Risk
Trifluralin
is
classified
as
a
Group
C
possible
human
carcinogen
with
carcinogenic
risk
quantified
by
the
Q
1*
approach.
Carcinogenic
dietary
risk
is
based
on
the
chronic
exposure
estimate
for
the
general
U.
S.
population
derived
from
the
same
residue,
percent
use,
and
averaged
consumption
data.
Chronic
dietary
risk
is
calculated
by
using
the
average
consumption
value
for
food
and
average
residue
values
on
those
foods
over
a
70­
year
lifetime.
A
risk
estimate
that
is
less
than
100%
of
the
chronic
RfD
(
the
dose
at
which
an
individual
could
be
exposed
over
the
course
of
a
lifetime
and
no
adverse
health
effects
would
be
expected)
does
not
exceed
the
Agency's
risk
concern.
Estimated
chronic
dietary
risk
is
below
the
Agency's
level
of
concern
for
all
populations
(<
1%
of
cPAD;
0.005
mg/
kg/
day).
The
estimated
exposure
of
the
general
U.
S.
population
to
trifluralin
is
0.000028
mg/
kg/
day
for
both
dietary
risk
assessment
models.
Applying
the
Q
1*
of
5.8
x
10­
3
(
mg/
kg/
day)­
1
to
the
exposure
value
results
in
a
cancer
risk
estimate
of
1.64
x
10­
7
(
DEEM­
FCID)
and
1.13
x
10­
7
(
Lifeline),
which
is
also
below
the
Agency's
level
of
concern.

Drinking
Water
Dietary
Risk
Drinking
water
exposure
to
pesticides
can
occur
through
groundwater
and
surface
water
contamination.
EPA
considers
both
acute
(
one
day)
and
chronic
(
multiple
year)
drinking
water
risks,
and
uses
either
modeling
or
actual
monitoring
data,
if
available,
to
estimate
those
risks.
Modeling
is
designed
to
provide
a
high­
end
estimate
of
exposure.
The
Agency
lacks
sufficient
data
to
accurately
determine
dietary
exposure
from
drinking
water.
Therefore,
residues
for
trifluralin
in
drinking
water
are
refined
by
PRZM­
EXAMS
modeling.
The
drinking
water
assessment
is
based
on
modeling
and
monitoring
data.
Modeling
was
completed
for
parent
as
well
as
combined
trifluralin
residues
observed
in
fate
studies.

Since
trifluralin
is
registered
on
several
crops,
Tier
II
modeling
crop
scenarios
were
selected
to
reflect
crops
with
the
highest
uses
of
trifluralin
(
soybeans
and
cotton),
the
maximum
application
rate
(
sugarcane),
and
availability
of
scenarios.
The
maximum
daily
peak
concentration
of
trifluralin
from
PRZM/
EXAMS
simulation
(
38.1
ppb)
is
greater
than
the
highest
concentration
in
the
USGS/
National
Water
Quality
Assessment
(
NAWQA)
monitoring
database
(
1.74
ppb)
for
surface
water.
However,
the
maximum
annual
average
trifluralin
concentration
in
surface
water
(
1.9
ppb)
is
comparable
to
time
weighted
annual
means
(
TWAM)
concentrations
in
USGS
monitoring
studies
(
0.618
ppb).
Additionally,
the
maximum
trifluralin
concentration
in
shallow
ground
water
(
0.035
ppb),
as
predicted
through
SCI­
GROW,
is
lower
than
the
99.8
percentile
concentration
in
the
NAWQA
ground
water
monitoring
database
(
0.012
ppb).

Residential
Risk
Residential
risk
assessment
considers
potential
pesticide
exposure,
other
than
dietary
and
occupational
exposure.
Exposure
may
occur
during
and
after
application
at
homes;
or
after
applications
at
golf
courses,
parks,
schools,
etc.
Each
route
of
exposure
(
oral,
dermal,
inhalation)
is
assessed,
where
appropriate,
and
risk
is
expressed
as
a
Margin
of
Exposure
(
MOE),
which
is
7
the
ratio
of
estimated
exposure
to
an
appropriate
No­
Observed­
Adverse­
Effect­
Level
(
NOAEL)
dose.
Based
on
its
uses,
trifluralin
is
assessed
for
the
residential
applicator
(
or
"
handler"),
for
children's
post­
application
oral
exposure
that
may
occur
from
turf
contact,
and
for
postapplication
dermal
contact.
Additionally,
carcinogenic
risk
is
also
estimated
by
the
Q
1*
approach.

Residential
exposure
scenarios
were
developed
for
trifluralin
and
based
on
the
use
sites,
formulations,
application
rates,
and
the
various
equipment
that
could
be
used
during
applications.
Residential
risk
estimates
are
also
based
on
estimates
(
and
assumptions)
regarding
the
body
weight
of
a
typical
homeowner/
applicator,
the
area
treated
per
application,
and
the
seasonal
duration
(
in
days)
of
exposure.
Note
also
that
residential
applicators
are
assumed
to
complete
all
elements
of
an
application
(
mix/
load/
apply)
without
use
of
protective
equipment
(
assessments
are
based
on
an
assumption
that
individuals
will
be
wearing
short­
sleeved
shirts
and
short
pants).

Short­
term
inhalation
risks
to
residential
handlers
and
dermal
and
inhalation
cancer
risks
to
residential
handlers
were
calculated
using
surrogate
data.
For
short­
term
non­
cancer
risks
to
residential
handlers,
a
margin
of
exposure
(
MOE)
of
less
than
100
exceeds
the
Agency's
level
of
concern.
For
residential
handlers,
the
calculations
of
short­
term
inhalation
non­
cancer
risk
indicate
that
the
MOEs
are
greater
than
100
for
all
residential
handler
scenarios.

For
residential
handler
scenarios,
cancer
risks
greater
than
1x10­
6
are
considered
to
be
of
concern.
The
calculations
of
residential
handler
cancer
risk
indicate
that
all
scenarios
have
a
cancer
risk
of
less
than
1x10­
6.

Post­
Application
Risk
Estimates
Exposure
to
trifluralin
occurs
in
the
residential
environment
following
applications
by
professionals,
or
non­
professionals,
to
lawns
and
ornamentals.
Exposure
to
trifluralin
also
occurs
following
applications
by
professionals
to
private
or
public
areas
such
as
golf
courses,
parkland,
etc.
For
this
assessment,
children
are
the
population
group
of
concern.
Since
systemic
toxicity
was
not
observed
in
a
dermal
toxicity
study,
up
to
a
dose
level
of
1,000
mg/
kg/
day,
the
only
risk
scenario
addressed
in
this
assessment
is
the
possible
oral
exposure
of
small
children
from
treated
turf,
or
from
treated
soil
(
i.
e.,
soil
ingestion,
granule
ingestion,
and
hand­/
object­
to­
mouth).
A
Margin
of
Exposure
of
100
(
or
more)
is
considered
adequately
protective
for
this
assessment.

For
non­
cancer
post­
application
risks,
since
there
is
no
short­
term
dermal
toxicological
endpoint
of
concern
for
trifluralin
and
no
intermediate­
term
dermal
exposure
is
anticipated,
the
only
assessment
is
for
incidental
ingestion
by
toddlers
by
hand­
to­
mouth
and
object­
to­
mouth
exposure
scenarios.
These
scenarios
produce
MOEs
greater
than
100,
therefore
risks
are
not
of
concern
to
the
Agency.
8
Since
there
was
no
dermal
endpoint
identified,
short­
term
post­
application
risks
are
based
on
incidental
oral
exposures.
For
residential
post­
application,
the
calculations
of
non­
cancer
risk
based
on
the
incidental
oral
NOAEL
endpoint
indicate
that
the
MOEs
were
more
than
100
for
residential
post­
application
scenarios.

In
addition,
the
Agency
determined
that
in
order
to
complete
the
residential
non­
cancer
postapplication
risk
assessment
a
combined
risk
assessment
would
be
required.
In
doing
so,
the
Agency
combines
risk
values
resulting
from
separate
post­
application
exposure
scenarios,
when
it
is
likely
that
they
can
occur
simultaneously
based
on
the
use
pattern
and
the
behavior
associated
with
the
exposed
population.
For
trifluralin,
the
Agency
combined
risk
values
for
post­
application
exposures
to
toddlers
associated
with
turf
applications
by
combining
risks
from
oral
exposures
via
transfer
of
residues
from
hands­
to­
mouth,
object­
to­
mouth,
and
incidental
soil
ingestion.
The
combined
MOE
for
these
scenarios
is
greater
than
100
and
is
not
considered
a
risk
concern.

Carcinogenic
risk
estimates
are
based,
in
part,
on
estimates
of
days
per
year
that
persons
are
exposed
to
treated
areas
following
trifluralin
use.
Based
on
the
transferable
residue
study,
postapplication
exposure
to
residential
turfgrass
and
golf
course
turfgrass
will
occur
on
the
day
of
application
(
day
zero)
following
two
applications,
each
year.
As
with
residential
applicators,
the
assessment
is
based
on
50
years
of
trifluralin
use
and
exposure.
Cancer
risks
are
5
x
10­
10
and
are
therefore,
not
of
concern.

Exposure
estimates
are
also
based
on
data
that
measured
the
transfer
of
residue
(
any
chemical)
from
the
surface
of
treated
turf
to
persons
while
doing
specific
activities.
As
in
the
postapplication
oral
assessment,
the
transferable
residue
estimate
(
0.0033
ug/
cm2)
is
taken
from
the
trifluralin­
specific
study
and
is
the
average
transferable
residues
at
day
0
(
after
day
0,
no
residues
were
detectable)
and
accounts
for
the
3lb
ai/
A
application
rate
used
on
turf.
These
estimates
form
the
basis
for
the
"
Lifetime
Average
Daily
Dermal
Dose",
or
LADD,
used
with
the
Q
1*
to
estimate
(
lifetime)
carcinogenic
risk
for
trifluralin
users.

The
Agency
has
determined
that
there
are
potential
post­
application
cancer
risks
for
adults
in
residential
areas
treated
with
trifluralin.
The
following
scenarios
were
assessed:
(
1)
dermal
exposure
to
residue
on
lawns,
(
2)
dermal
exposure
to
golf
course
turfgrass,
and
(
3)
dermal
exposure
to
residue
on
home
gardens.
For
residential
post­
application
scenarios,
cancer
risks
greater
than
1x10­
6
are
considered
to
be
of
concern.
The
calculation
of
residential
post­
application
cancer
risk
indicate
that
all
scenarios
have
a
cancer
risk
of
less
than
1
x10­
10
and
are
not
considered
a
risk
concern.

For
the
residential
turfgrass
scenario,
the
Agency
combined
the
cancer
risks
for
residential
handlers
applying
granular
formulation
to
lawns
with
post­
application
cancer
risks
to
adults
from
exercising
on
just­
treated
lawns.
The
combined
handler
plus
post­
application
cancer
risk
associated
with
applications
to
residential
turfgrass
is
5.4
x
10­
7.
This
is
below
EPA's
level
of
concern
for
cancer.
(
Note:
combining
short­
term
risks
was
not
done,
since
there
are
no
shortterm
post­
application
risks
because
there
is
no
short­
term
dermal
endpoint
of
concern.)
9
Aggregate
Risk
Aggregate
exposure
assessment
is
based,
in
part,
on
the
same
assumption
that
there
is
a
predictable
level
of
chronic
pesticide
exposure,
attributable
to
food
and
drinking
water,
and
this
level
is
estimated
on
a
per
day
basis
(
mg/
kg/
day)
by
using
averaged
estimates
of
residue,
use,
and
consumption.
For
trifluralin,
homeowner
use
is
highly
seasonal
(
mostly
early
Spring)
and
this
exposure
will
likely
be
acute
(
one
day
of
golf)
or
short­
term
(
multiple
residential
applications).
The
route
of
exposure
may
be
oral
(
children
on
turf),
dermal
(
at
application
or
post­
application),
or
by
inhalation
(
at
application).

Aggregate
Short­
Term
Risk:
The
aggregate
(
3
specific
exposure
scenarios)
incidental
oral
exposure
estimate
for
children
on
turf
is
0.00009
mg/
kg/
day.
When
combined
with
the
estimated
chronic
dietary
exposure
(
0.000051
mg/
kg/
day)
for
children
1­
2
years
old,
the
sum
is
0.00014
mg/
kg/
day.
Compared
to
the
appropriate
dose
(
10
mg/
kg/
day)
for
short­
term
incidental
oral
risk
assessment,
this
aggregate
exposure
estimate
is
much
greater
than
the
target
MOE
of
100,
and
a
conclusion
of
safety
can
be
made.

Aggregate
Carcinogenic
Risk:
When
using
the
Q
1*
approach
to
assess
a
pesticide,
the
Agency
considers
all
exposure
to
be
additive
to
aggregate
carcinogenic
risk,
regardless
of
exposure
route
or
exposure
duration
(
per
season).
For
trifluralin,
this
means
that
the
chronic
exposure
from
foods
(
0.000022
mg/
kg/
day)
is
added
to
chronic
exposure
due
to
drinking
water
(
0.000008
mg/
kg/
day),
which
is
added
to
exposure
estimated
for
residential
use.
Based
on
this
assumption,
carcinogenic
risk
estimates
are
made
for
those
applying
trifluralin
themselves,
each
season,
throughout
adulthood
(
50
years).

As
previously
noted,
the
exposure
and
carcinogenic
risk
estimates
for
residential
applicators
varies
significantly
depending
on
the
application
method,
even
if
other
inputs
(
rate
and
area
treated)
remain
the
same.
Since
carcinogenic
risk
assessment
attempts
to
reflect
long­
term
exposure,
the
most
appropriate
exposure
estimate
would
be
based
on
the
most
common
application
method;
the
push­
type
spreader.
The
Lifetime
Average
Daily
Dose
estimated
for
this
application
method
is
negligible
(
0.0000006
mg/
kg/
day),
and
when
added
to
the
chronic
dietary
(
food
and
water)
exposure
the
aggregate
carcinogenic
risk
estimate
is
2x10­
7.

Recommendations
In
addition
to
being
classified
as
a
possible
human
carcinogen
trifluralin
is
also
classified
as
a
skin
sensitizer.
EPA
has
no
method
of
quantifying
risk
due
to
skin
sensitization
and
remains
concerned
about
dermal
sensitization
reactions
to
adults
and
children
who
are
exposed
to
trifluralin
in
residential
settings.
Therefore,
it
is
recommended
that
all
products
containing
trifluralin
be
labeled
as
"
SENSITIZER"
and
state
that
"
skin
contact
should
be
avoided".
10
Tolerance
Reassessment
Currently,
there
are
35
tolerances
(
majority
at
0.05
ppm)
established
for
residues
of
trifluralin
in
or
on
raw
agricultural
commodities.
However,
there
is
no
tolerance
for
trifluralin
in
or
on
raw
agricultural
commodities
for
mint
oil.
Available
data
show
that
residues
of
trifluralin
in
foods
prepared
with
mint
oil
will
not
exceed
the
existing
raw
agricultural
commodity
tolerance.
As
a
result,
the
Agency
has
made
a
safety
finding
that
trifluralin
is
safe
as
currently
used
in
pesticide
products.
Therefore,
the
Agency
will
be
proposing,
via
a
Federal
Register
(
FR)
notice,
to
establish
a
permanent
tolerance
of
2.0
ppm
for
mint
oil.
Additionally,
existing
tolerances
for
residues
of
trifluralin
do
not
exceed
the
Agency's
risk
concern
and
will
be
considered
reassessed
under
section
408(
q)
of
the
FFDCA.
