Oxadiazon
Summary
Uses
°
Oxadiazon
is
registered
for
commercial
use
on
turf
grown
on
golf
courses
(~
77%
of
total
use)
and
in
apartment/
condominium
complexes,
parks,
athletic
fields,
playgrounds,
and
cemeteries
(~
12%
of
total
use).
In
addition,
oxadiazon
is
used
on
sod
farms
and
on
conifer
nurseries
and
landscapes
(
i.
e.
industrial
sites,
ornamental,
roadside
plantings,
woody,
ornamental
shrubs,
vines
and
trees,
and
herbaceous
ornamentals)

$
Oxadiazon
is
a
pre­
emergent
or
early
post­
emergent
oxadiazole
herbicide
used
to
control
grassy
weeds
(
e.
g.
goosegrass
and
crabgrass)
and
broadleaf
weeds
in
turf
and
ornamentals.
°
Annual
usage
is
approximately
249,000
pounds
on
52,000
acres.
Oxadiazon
is
used
primarily
in
the
South
(~
71%)
and
predominantly
on
golf
courses
(~
77%).

Health
Effects
°
In
humans,
acute
exposure
to
oxadiazon
can
cause
irritation
to
the
skin,
eyes
and
mucous
membranes.
°
In
both
subchronic
and
chronic
studies,
effects
on
the
liver
were
consistent
among
the
species
tested
(
rat,
dog,
mouse).
°
Oxadiazon
is
classified
as
"
likely
to
be
carcinogenic
to
humans"
based
on
studies
that
showed
an
increase
in
the
incidence
of
liver
tumors
in
two
species
(
mice
and
rats)
following
chronic
exposure
to
oxadiazon.

Human
Health
Risks
Dietary
Risk
°
There
are
no
food
or
feed,
or
anticipated
food
or
feed
uses
for
oxadiazon.
The
Registrant
is
not
supporting
any
tolerances
for
oxadiazon
in
the
United
States.
Existing
tolerances
are
in
the
process
of
revocation.
Likewise,
there
are
no
Canadian
or
Mexican
tolerances
for
oxadiazon.

Drinking
Water
Risk
°
There
is
a
potential
drinking
water
risk
of
concern
for
infants
and
children
chronically
exposed
to
oxadiazon
via
drinking
water
from
surface
water
sources.
°
The
cancer
risk
exceeds
the
Agency's
level
of
concern
for
lifetime
exposure
to
oxadiazon
in
surface
and
ground
water.
°
Acute
exposure
to
oxadiazon
in
ground
and
surface
water
is
not
of
concern.

Residential
Risk
°
The
oxadiazon
label
indicates
that
the
purchase,
storage
and
application
of
this
pesticide
is
limited
to
commercial
nursery,
turf
and
landscape
personnel,
and
the
product
is
not
available
to
homeowners.
Post­
application
residential
exposure
scenarios
include
apartment
complexes,
golf
courses,
and
playgrounds.
°
In
all
risk
scenarios,
residential
exposure
to
oxadiazon
was
of
little
or
no
concern.

Aggregate
Risk
(
combined
risks
from
food,
residential,
and
water)

°
The
Agency
did
not
perform
an
aggregate
risk
assessment
as
part
of
this
reregistration
review
for
oxadiazon,
because
the
conservative
estimate
of
risk
from
chronic
exposure
to
drinking
water
already
exceed
the
level
of
concern.
°
There
are
no
remaining
food
uses.

Occupational
Risk
°
The
Agency
has
determined
that
there
are
potential
exposures
to
occupational
mixers,
loaders,
applicators,
or
other
occupational
handlers
during
standard
usepatterns
associated
with
oxadiazon.

$
Dermal
route
is
the
route
of
consequence.

$
There
is
potential
non­
cancer
risk
associated
with
low­
pressure
handwand
application
of
wettable
powder
formulations.

$
None
of
the
evaluated
occupational
scenarios
have
cancer
risks
that
exceed
the
Agency's
level
of
concern.

Environmental
Fate
and
Transport
°
Environmental
fate
studies
indicate
that
oxadiazon
persists
in
the
environment
bound
to
organic
matter.
°
In
clear,
shallow
bodies
of
water,
oxadiazon
not
bound
to
organic
matter
may
be
degraded
by
sunlight.
Alternatively,
oxadiazon
is
defined
as
a
light­
dependent
peroxidizing
herbicide
(
LDPH),
which
suggests
that
toxicity
is
greater
in
the
presence
of
light.
°
Studies
indicate
that
after
application
to
soil,
oxadiazon
remains
near
the
surface,
and
can
be
transported
via
runoff
to
nearby
surface
water
bodies.

$
Leaching
from
surface
soils
to
groundwater
is
expected
to
be
low
or
negligible,
unless
the
soil
is
very
porous.

$
Since
this
stable
compound
can
bind
to
particulate
and
organic
matter,
oxadiazon
residues
can
accumulate
in
sediments
at
the
bottom
of
bodies
of
water.

$
Oxadiazon
may
accumulate
in
aquatic
organisms
such
as
fish;
however,
as
observed
in
studies
using
bluegill
sunfish,
the
tendency
toward
bio­
accumulation
can
be
offset
by
a
rapid
rate
of
removal.

Environmental
Risks
Avian
Risk
$
Chronic
exposure
may
result
in
risk
to
birds
that
feed
on
plants
and
grass
(
e.
g.
ducks,
geese).

$
Exposure
from
the
granular
formulation
was
evaluated
because
birds
may
be
exposed
to
granular
pesticides
through
ingestion
when
foraging
for
food
or
grit.

$
All
scenarios
for
the
granular
formulation
resulted
in
no
acute
risk
to
birds.

Aquatic
Species
Risk
°
Chronic
exposure
to
oxadiazon
may
result
in
risk
to
freshwater
and
estuarine/
marine
fish
and
aquatic
invertebrates.

$
Oxadiazon
residues
can
accumulate
in
sediments
and
increase
the
potential
for
chronic
risk
to
aquatic
organisms
that
live
in
or
on
the
sediment.
In
order
to
better
understand
this
potential
risk,
the
Agency
is
requiring
appropriate
sediment
toxicity
testing
(
acute
and
chronic)
on
this
compound.

$
Enhanced
toxicity
through
exposure
to
sunlight
may
increase
risk
to
aquatic
organisms
that
inhabit
small,
shallow
water
bodies.

$
The
herbicidal
properties
of
oxadiazon
also
suggest
the
potential
for
acute
toxicity
to
aquatic
plants
and
the
possibility
of
alterations
to
aquatic
habitats.
This
can
have
an
indirect
effect
on
aquatic
populations
by
decreasing
plant
cover.

Mammalian
Risk
°
Acute
exposure
to
birds
and
mammals
presents
minimal
risk.
°
Chronic
exposure
could
result
in
risk
to
mammalian
herbivores
and
insectivores.

Non­
target
Plants
and
Animal
Risk
$
Oxadiazon
exposure
may
present
a
risk
to
non­
target
aquatic
organisms.

$
The
EPA
is
in
the
process
of
determining
if
oxadiazon
presents
a
risk
to
endangered
aquatic
species
(
fish
and
invertebrates).
