Page
1
of
4
Diuron
Summary
July
30,
2002
Uses
°
Diuron
is
an
herbicide,
mildewcide
and
algaecide
and
is
used
pre­
and
post­
emergent
herbicide
treatment
on
a
variety
of
both
crop
and
non­
crop
areas;
as
a
mildewcide
in
paints
and
stains,
and
as
an
algaecide
in
commercial
fish
production.
°
On
average,
approximately
nine
to
ten
million
pounds
of
active
ingredient
are
used
annually.
Approximately
two
thirds
are
used
on
agricultural
crops
and
the
remaining
one
third
on
non­
crop
areas.

Human
Health
Effects
°
Diuron
has
low
acute
toxicity
by
the
oral,
dermal
or
inhalation
exposure
routes.
Diuron
is
not
an
eye
or
skin
irritant
and
is
not
a
skin
sensitizer.
The
primary
organs
affected
by
chronic
diuron
are
the
hematopoietic
system
(
blood),
the
bladder,
and
renal
pelvis
(
kidney).
Available
data
do
not
reveal
any
developmental
or
reproductive
toxicity.
°
Diuron
is
classified
as
a"
known/
likely"
human
carcinogen
based
on
urinary
bladder
tumors.
°
A
metabolite
of
diuron,
MCPDMU,
has
been
assessed
for
cancer
by
analogy
to
a
structurally
similar
compound,
monuron,
and
represents
worst
case.
It
is
possible
that
MCPDMU
is
less
toxic
than
monuron;
it
is
unlikely
that
it
is
more
toxic.
The
estimated
risk
for
monuron
is
based
on
a
Q*
of
1.52
x
10­
2
(
mg/
kg/
day)­
1.

Risks
Dietary
Risk
°
Acute
dietary
risks
from
food
treated
with
diuron
are
not
of
concern
because
no
adverse
effects
attributed
to
a
single
exposure
were
identified
in
any
available
study.
°
Chronic
dietary
risks
from
food
treated
with
diuron
are
not
of
concern.
The
chronic
dietary
(
food
only)
risk
estimate
is
3%
of
the
chronic
population
adjusted
dose
(
cPAD)
for
the
U.
S.
population
and
7%
of
the
cPAD
for
children
1­
6
years,
the
most
sensitive
subpopulation.
°
Based
on
a
Q*
of
1.91
x
10
­
2
(
mg/
kg/
day)­
1,
the
dietary
cancer
risk
estimate
for
diuron
is
1.68
x
10
­
6
(
mg/
kg/
day)­
1,
slightly
over
the
Agency's
level
of
concern
[
1.0
x
10
­
6
(
mg/
kg/
day)­
1].
°
Dietary
exposure
is
based
on
field
trial
data
adjusted
for
the
percent
of
the
crop
treated
and
processing
data
for
sugarcane
refined
into
sugar
and
molasses.
In
addition,
Page
2
of
4
processing
data
for
apple,
citrus,
and
grapes
were
used
in
the
assessment.
°
Chronic/
cancer
dietary
risk
can
be
further
refined.
°
USDA
Pesticide
Data
Program
monitoring
data
show
no
detectable
residues
of
diuron,
when
monitoring
for
the
parent
compound
only.

Drinking
Water
°
For
diuron,
only
chronic
and
cancer
drinking
water
risks
are
potentially
of
concern
based
on
modeled
estimates.
For
chronic
risk,
only
exposure
from
surface
water
is
of
concern.
°
For
chronic
risk,
the
estimated
environmental
concentrations
(
EECs)
for
surface
water
from
PRZM/
EXAMS
(
42
ppb)
exceeds
the
drinking
water
level
of
comparison
(
DWLOC)
of
28
ppb
for
the
most
sensitive
population
subgroup
(
children
1
­
6),
in
the
Flatwood
area
of
Florida,
at
the
highest
application
rate.
°
Monitoring
data
from
the
Flatwood
area
of
Florida
show
levels
of
diuron
(
parent
compound
only)
ranging
from
0.2
­
0.4
µ
g/
L
for
surface
water
and
8.3
­
120
µ
g/
kg
for
sediment.
°
Residue
data
are
required
to
support
the
9.6
lbs
ai/
A
per
year
application
rate
for
citrus
in
Florida.

Residential
Risk
°
The
only
residential
risk
potentially
of
concern
is
for
cancer
risk
to
applicators
using
diuron
treated
paints
and
stains
applied
with
airless
paint
sprayer
or
paint
brush.
Depending
on
the
exposure
data
used,
application
method
employed,
and
the
amount
applied,
the
calculated
risk
to
applicators
range
from
3
x
10­
10
to
3.4x10­
6,
assuming
the
average
body
weight
of
the
adult
handler
is
70
kg,
15
gallons
of
diuron
treated
paint
for
an
airless
sprayer,
two
gallons
for
paintbrush
applying
paint
and,
five
gallons
for
paintbrush
applying
stain.
°
The
residential
cancer
risk
assessment
assumes
that
the
average
lifetime
is
70
years
with
an
exposure
duration
of
50
years.
For
paint
exposure,
it
is
assumed
that
the
homeowner
would
only
paint
two
days
per
year.
For
pond
use,
it
is
assumed
that
the
homeowner
would
apply
diuron
once
per
month
or
12
times
a
year.
°
Less
than
5%
of
all
paint
contains
diuron.
Therefore,
it
is
unlikely
that
a
homeowner
would
apply
from
two
to
five
gallons
of
diuron­
containing
paint
or
stain
two
times
per
year
for
50
years.
°
Post­
application
exposure
to
children
is
expected
to
be
minimal
as
indicated
in
modeled
estimates
of
inhaled
diuron
from
a
screening­
level
inhalation
assessment
combined
diuron's
low
vapor
pressure.

Aggregate
Risk
Page
3
of
4
°
The
aggregate
risk
assessment
for
diuron
examines
the
combined
risk
from
exposure
through
food,
drinking
water,
and
residential
use.
°
There
are
no
adverse
effects
expected
from
a
single
exposure
to
diuron;
therefore,
an
acute
risk
assessment
was
not
conducted.
Short­
term
aggregate
risks
from
food,
residential
inhalation,
and
drinking
water
are
not
of
concern.
°
Estimated
aggregate
chronic
risk
(
noncancer)
concentrations
of
diuron
and
its
metabolites
in
surface
water
slightly
exceed
the
chronic
DWLOC
in
the
Flatwood
area
of
Florida.
Because
field
trial
residue
levels
(
from
maximum
labeled
rates)
were
used
in
the
assessments,
dietary
risks
are
high
end
estimates
and
may
be
refined
further.
°
An
aggregate
cancer
estimate
has
not
been
calculated
since
conservative
assumptions
were
used
in
both
the
dietary
and
drinking
water
assessments.
Thus,
aggregation
of
these
assessments
would
result
in
an
even
more
conservative
expression
of
risk.
°
Dietary
risk
estimates
can
be
further
refined
with
processing
data
and
monitoring
data
that
accounts
for
diuron
and
its
metabolites.
°
Additional
targeted
drinking
water
monitoring
will
be
required
to
fully
characterize
drinking
water
risk
of
diuron
and
its
metabolites.
°
Because
of
the
low
percent
of
paint
containing
diuron,
exposure
to
home
applicators
is
not
likely
to
be
a
significant
contributor
to
aggregate
risk.

Occupational
Risks
°
The
Agency
has
identified
31
handler
scenarios
resulting
from
mixing/
loading
and
applying
diuron
for
crop
and
non­
crop
uses.
Of
the
31
scenarios,
all
short­
and
intermediate­
term
exposures
resulted
in
a
Margin
of
Exposure
(
MOE)
at
or
near
the
target
of
100
with
personal
protective
equipment
(
PPE)
and
engineering
controls
(
e.
g.,
closed
mixing
and
loading
systems),
as
appropriate.
°
For
the
cancer
assessment,
the
following
scenarios
are
potentially
of
concern:
applying
with
a
right­
of­
way
sprayer;
applying
in
an
industrial/
commercial
setting
with
a
highpressure
handwand;
mixing/
loading/
applying
wettable
powder
products
with
a
lowpressure
handwand;
loading
and
applying
with
a
gravity
feed
backpack
spreader;
and
loading
and
applying
with
a
belly
grinder.
°
For
the
occupational
paint
assessment,
the
following
scenarios
are
potentially
of
concern:
painters
using
airless
sprayers;
cancer
risk
for
primary
handlers
in
paint
manufacturing
facilities;
cancer
risk
for
commercial
painters
using
an
airless
sprayer;
and
cancer
risk
for
painters
using
a
brush.
°
For
commercial
catfish
ponds,
cancer
is
not
a
concern
if
closed
mixing
and
loading
systems
are
used.

Post
Application
Risks
°
Only
the
crops
that
can
receive
foliar
applications
(
oats,
wheat,
birdsfoot
trefoil,
grass
Page
4
of
4
grown
for
seed,
alfalfa,
asparagus,
pineapple,
and
sugarcane)
are
assessed
for
post
application
risks.
°
For
field
and
row
crops
and
sugarcane,
medium
exposure
activities
such
as
moving
irrigation
equipment
and
scouting
mature
plants
are
potentially
of
concern
for
cancer
at
the
typical
application
rate
and
current
12­
hour
restricted
entry
interval
(
REI).
°
For
asparagus
and
pineapple,
all
activities
assessed
are
potentially
of
concern
at
typical
application
rates.

Environmental
Fate
and
Effects
Risks
Avian
°
Diuron
is
slightly
toxic
to
bobwhite
quail
and
practically
non­
toxic
to
the
mallard
duck
on
an
acute
oral
basis.
It
is
practically
non­
toxic
to
bobwhite
quail
and
slightly
toxic
to
mallard
duck
on
a
subacute
dietary
basis.
°
The
risk
quotients
(
RQs)
for
avian
species
range
from
0.01
­
1.66.

Aquatic
Species
°
Diuron
is
moderately
toxic
to
the
majority
of
aquatic
animals
tested
(
including
rainbow
trout,
bluegill
sunfish,
water
flea,
striped
mullet,
sheepshead
minnow,
Eastern
oyster,
and
brown
shrimp).
°
Diuron
is
highly
toxic
to
cutthroat
trout
and
scuds
and
slightly
toxic
to
fathead
minnow.
°
The
RQs
for
aquatic
species
range
from
0.01
­
9.
°
The
Agency
has
asked
the
registrant
to
submit
data
on
the
environmental
fate
of
diuron
and
its
degradate
MCPDMU.

Mammalian
°
There
is
potential
chronic
risk
to
small
mammals
feeding
on
short
grass
or
broad
leaf
plants.
°
The
RQs
for
mammalian
species
range
from
<
0.01
­
9.22.

Non­
target
Plants
°
There
are
risks
to
non­
target
terrestrial
and
aquatic
plants.
°
The
RQs
for
non­
target
plant
species
range
from
1.25
­
172.
