United
States
Prevention,
Pesticides
EPA­
738­
F­
04­
003
Environmental
Protection
And
Toxic
Substances
December
30,
2003
Agency
(
7508C)

R.
E.
D.
FACTS
Oxadiazon
Pesticide
Reregistration
All
pesticides
sold
or
distributed
in
the
United
States
must
be
registered
by
EPA,
based
on
scientific
studies
showing
that
they
can
be
used
without
posing
unreasonable
risks
to
humans
or
the
environment.
Because
of
advances
in
scientific
knowledge,
the
law
requires
that
pesticides
which
were
first
registered
before
November
1,
1984,
be
reregistered
to
ensure
that
they
meet
today's
more
stringent
standards.

In
evaluating
pesticides
for
reregistration,
EPA
obtains
and
reviews
a
complete
set
of
studies
from
pesticide
producers,
describing
the
human
health
and
environmental
effects
of
each
pesticide.
To
implement
provisions
of
the
Food
Quality
Protection
Act
of
1996,
EPA
considers
the
special
sensitivity
of
infants
and
children
to
pesticides,
as
well
as
aggregate
exposure
of
the
public
to
pesticide
residues
from
all
sources,
and
the
cumulative
effects
of
pesticides
and
other
compounds
with
common
mechanisms
of
toxicity.
The
Agency
develops
any
mitigation
measures
or
regulatory
controls
needed
to
effectively
reduce
each
pesticide's
risks.
EPA
then
reregisters
pesticides
that
meet
the
safety
standard
of
the
FQPA
and
can
be
used
without
posing
unreasonable
risks
to
human
health
or
the
environment.

When
a
pesticide
is
eligible
for
reregistration,
EPA
explains
the
basis
for
its
decision
in
a
Reregistration
Eligibility
Decision
(
RED)
document.
This
fact
sheet
summarizes
the
information
in
the
RED
document
for
oxadiazon
(
Chemical
Code
No.
109001;
Case
No.
2485).

Use
Profile
Oxadiazon
is
a
pre­
emergent
or
early
post­
emergent
oxadiazole
herbicide
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).
Annual
usage
is
approximately
249,000
pounds
on
52,000
acres.

Regulatory
History
Oxadiazon
was
registered
in
1978.
A
Phase
Four
generic
data
call­
in
(
DCI)
was
issued
in
May
of
1991.
Due
to
additional
data
required
under
FIFRA
as
amended
in
1988,
the
oxadiazon
registrant
decided
to
no
longer
support
food
uses
of
oxadiazon.
On
June
3,
2002,
the
Agency
considered
the
FQPA
safety
finding
to
be
met
and
counted
the
oxadiazon
tolerances
as
reassessed.
There
are
no
CODEX,
Canadian,
or
Mexican
tolerances
for
oxadiazon
residues.

Human
Health
Toxicity
2
Assessment
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.

Dietary
Risks
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
have
been
revoked.
Likewise,
there
are
no
Canadian
or
Mexican
tolerances
for
oxadiazon.

Worker
Risks
Cancer
risks
for
occupational
handlers
of
wettable­
powder
formulations
of
oxadiazon
are
of
concern.
Exposure
scenarios
of
concern
include
mixing/
loading/
applying
wettable
powder
formulations.
To
reduce
these
risks,
the
wettable
powder
formulations
will
be
packaged
in
water­
soluble
packaging
(
WSP)
only.

Residential
and
Other
Nonoccupational
Risks
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.
The
Agency
has
concluded
that
residential
exposure
to
oxadiazon
is
not
of
concern.

FQPA
Considerations
Given
that
there
are
no
remaining
food/
feed
uses
for
oxadiazon,
and
given
that
all
food
tolerances
have
been
revoked,
this
pesticide
no
longer
falls
under
the
scope
of
FQPA.
As
such,
no
quantitative
aggregate
assessment
of
risk
from
dietary
and
residential
was
conducted.
EPA
has
qualitatively
evaluated
the
likelihood
of
concurrent
exposures
from
different
sources
of
oxadiazon
for
the
general
population,
including
children.
Because
of
the
relatively
low
volume
of
oxadiazon
use
on
sites
other
than
golf
courses,
its
specialized
use
pattern,
and
its
relatively
high
cost,
concurrent
exposures
are
not
expected.

In
addition,
oxadiazon
was
not
assessed
for
the
cumulative
effects
of
pesticides
having
a
common
mechanism
of
toxicity.
The
Agency
does
not
have
sufficient
information
at
this
time
concerning
common
mechanism
issues
to
determine
whether
or
not
oxadiazon
shares
a
common
mechanism
of
toxicity
with
other
substances,
including
other
oxadiazoles.
Therefore,
for
the
purposes
of
this
risk
assessment,
the
Agency
has
assumed
that
oxadiazon
does
not
share
a
common
mechanism
of
toxicity
with
any
other
chemicals.
3
Environmental
Assessment
Ecological
Risks
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.

To
mitigate
ecological
risks
the
technical
registrants
has
agreed
to
label
amendments
which
include
reductions
in
application
rates.
In
addition,
the
Agency
is
requiring
that
the
registrant
submit
data
related
to
fish
and
invertebrate
toxicity,
as
well
as
data
from
toxicity
studies
with
aquatic
plants
and
sediment.

Summary
This
Fact
Sheet
explains
the
Agency's
decision
regarding
the
reregistration
eligibility
of
the
registered
uses
of
oxadiazon.
The
Agency
has
found
that
the
current
uses
of
oxadiazon
are
eligible
for
reregistration,
provided
the
changes
specified
in
the
RED
are
made
to
the
packaging
and
labels.

Additional
Data
Required
EPA
is
requiring
the
following
confirmatory
data
requirements
for
oxadiazon:

870.3465:
28­
day
inhalation
toxicity
850.1300:
Early­
Life
Stage
in
Freshwater
and
Estuarine/
Marine
Fish
850.1350:
Life
Cycle
in
Freshwater
and
Estuarine/
Marine
Invertebrates
850.4100:
Seedling
Emergence
(
Tier
1)

850.4150:
Vegetative
Vigor
(
Tier
1)

850.4225:
Seedling
Germination/
Emergence
850.4250:
Vegetative
Vigor
(
Tier
2)

835.4300:
Aerobic
Aquatic
Metabolism
Aquatic
Phototoxicity
Studies
(
Fathead
minnow)

Acute
and
Chronic
Sediment
Toxicity
Testing
Water
Monitoring
Study
Product
Labeling
Changes
Required
All
oxadiazon
end­
use
products
must
comply
with
EPA's
current
pesticide
product
labeling
requirements.
For
a
comprehensive
list
of
labeling
requirements,
please
see
Section
V
of
the
oxadiazon
RED
document.

Regulatory
EPA
has
determined
that
all
products
containing
oxadiazon
as
the
active
ingredient
are
eligible
for
reregistration,
provided
changes
specified
in
the
oxadiazon
4
Conclusion
RED
are
incorporated
into
the
label
and
additional
data
identified
in
Section
V
of
the
RED
confirm
this
conclusion.

For
More
Information
EPA
is
requesting
public
comments
on
the
Reregistration
Eligibility
Decision
(
RED)
document
for
oxadiazon
during
a
60­
day
time
period,
as
announced
in
a
Notice
of
Availability
published
in
the
Federal
Register.
To
obtain
a
copy
of
the
oxadiazon
RED
document,
please
contact
the
OPP
Public
Docket
(
7502C),
US
EPA,
Ariel
Rios
Building,
1200
Pennsylvania
Avenue,
NW,
Washington,
DC
20460­
0001,
telephone:
(
703)
305­
5805.
Electronic
copies
of
the
oxadiazon
RED
and
all
supporting
documents
are
also
available
on
the
Agency's
website
at
http://
www.
cfpub.
epa.
gov/
oppref/
rereg/
status.
cfm?
show=
rereg.

For
more
information
about
EPA's
pesticide
reregistration
program
or
the
oxadiazon
RED,
please
contact
the
U.
S.
EPA,
OPP,
Special
Review
and
Reregistration
Division
(
7508C),
Washington,
DC
20460­
0001,
telephone:
(
703)
308­
8000.

For
more
information
about
the
health
effects
of
pesticides,
or
for
assistance
in
recognizing
and
managing
pesticide
poisoning
symptoms,
please
contact
the
National
Pesticide
Information
Center
(
NPIC).
Call
toll­
free
(
800)
858­
7378,
from
6:
30
am
to
4:
30
pm
Pacific
Time,
or
9:
30
am
to
7:
30
pm
Eastern
Standard
Time,
seven
days
a
week.
Their
internet
address
is
http://
www.
npic.
orst.
edu.
