Document ID: EPA-HQ-OPP-2002-0309-0005
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2002-12-03T05:00Z

1
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
March
05,
2002
PC
Code:
109001
DP
Barcode
D280320
MEMORANDUM
Subject:
EFED
Risk
Assessment
for
the
Reregistration
Eligibility
Decision
of
Oxadiazon
To:
Margaret
Rice,
Branch
Chief
Veronique
LaCapra,
Chemical
Review
Manager
Reregistration
Branch
II
Special
Review
and
Reregistration
Division
(
7508C)

From:
Miachel
Rexrode,
Ph.
D.,
Aquatic
Biologist
José
Luis
Meléndez,
Chemist
Rodolfo
Pisigan,
Jr.,
Ph.
D.,
Chemist
Environmental
Risk
Branch
V
Environmental
Fate
and
Effects
Division
(
7507C)

Through:
Mah
Shamim,
Ph.
D.,
Chief
Jean
Holmes,
Risk
Assessment
Process
Leader
Environmental
Risk
Branch
V
Environmental
Fate
and
Effects
Division
(
7507C)

This
memo
provides
a
summary
of
the
EFED
Environmental
Risk
Assessment
for
the
Oxadiazon
Reregistration
Eligibility
Document
(
RED).
Oxadiazon
is
registered
for
use
on
terrestrial
non­
food
crop
sites,
including
golf
courses,
landscape
(
turf
and
ornamentals),
nurseries,
and
roadside
areas.
Based
on
laboratory
and
field
data,
oxadiazon
is
a
persistent,
lipophilic
compound
that
has
a
low
mobility
in
most
soils,
and
may
be
susceptible
to
aqueous
photolysis.
Oxadiazon
is
also
a
light­
dependent
peroxidizing
herbicide
(
LDPH)
that
has
the
potential
for
the
induction
of
phototoxicity.

Our
risk
assessment
shows
that
oxadiazon
use
has
the
potential
for
chronic
exposure
to
aquatic
organisms
that
could
result
in
reproductive
effects
to
estuarine/
marine
fish
and
aquatic
invertebrates.
Other
aquatic
issues
of
concern
include
oxidiazon's
ability
to
bind
and
accumulate
in
the
sediment
thus
resulting
in
possible
toxic
exposure
to
aquatic
organisms
that
live
in
or
near
the
benthos.
Since
oxadiazon
exposure
to
light
has
the
potential
for
free
radical
generation,
phototoxicity
may
be
another
issue
of
toxic
concern
for
aquatic
organisms.
2
Acute
exposure
of
oxadiazon
(
emulsifiable
concentrate
and
granular)
to
birds
and
mammals
should
not
present
short
term
toxic
risk.
However,
the
potential
for
chronic
risk
to
mammals
and
birds
may
result
in
reproductive
effects.

EFED
also
has
a
concern
that
acute
exposure
of
oxadiazon
to
aquatic
and
terrestrial
systems
may
result
in
the
potential
for
risk
to
endangered
species
that
include
mammals,
birds,
fish
and
aquatic
invertebrates.
Since
this
compound
is
a
herbicide,
there
can
be
an
assumption
of
potential
risk
to
nontarget
plants
(
terrestrial,
semi­
aquatic
and
aquatic).
The
studies
that
have
been
submitted
show
that
this
compound
is
potentially
a
toxic
risk
to
aquatic
vascular
and
nonvascular
plants.
However,
this
possible
risk
to
nontarget
terrestrial
plants
cannot
be
fully
assessed
at
this
time
due
to
the
lack
of
acceptable
data.

Outstanding
Data
Requirements
Environmental
Fate:

The
environmental
fate
data
base
is
largely
complete.
EFED
will
not
require
additional
studies
at
this
time.

Ecological
Effects:

72­
4
(
a)
Early­
Life
Stage
Estuarine
Fish
72­
4
(
b)
Life
Cycle
Estuarine
Invertebrate
123­
1
Seedling
Emergence
and
Vegetative
Vigor­
using
a
liquid
TEP
to
represent
both
granular
and
liquid
formulations
(
note
in
the
case
that
liquid
formulations
are
not
supported
for
reregistration,
only
seedling
emergence
testing
would
be
required;
vegetative
vigor
testing
is
not
required
for
granular
formulations)

123­
2
Aquatic
plant
testing
(
TierII)
is
required
because
oxadiazon
has
outdoor
nonresidential
terrestrial
uses
that
may
move
off­
site
by
runoff
and/
or
aerial
spray
drift.
The
following
species
should
be
tested
at
Tier
II:
Kirchneria
subcapitata
(
Selenastrum
capricornutum),
Skeletonema
costatum,
and
Anabaena
flos­
aquae.

70­
1
Acute
and
Chronic
Sediment
Toxicity
Testing
­
Oxadiazon
shows
a
high
K
OC,
combined
with
a
high
persistence
exhibited
in
the
aerobic
soil
metabolism,
and
the
anaerobic
aquatic
metabolism
(>
10
days).
These
fate
properties
indicate
that
there
may
be
risk
to
benthicdwelling
aquatic
invertebrates,
however
the
potential
for
risk
cannot
be
assessed
until
data
have
been
submitted.
The
Chronic
Sediment
Toxicity
Testing
data
requirement
is
triggered,
with
Chironomus
tentans
and
the
Acute
Chronic
Sediment
Toxicity
Testing
data
requirement
is
triggered,
with
both
Hyalella
azteca,
and
Chironomus
tentans.

70­
1
Phototoxicity
studies
on
fathead
minnow.
A
subchronic
exposure
duration
would
be
adequate
for
proof
of
concept.
Behavioral
observations
should
be
conducted
in
addition
to
3
mortality,
growth,
and
morphology.
All
studies
should
be
conducted
under
defined
light
conditions.

Endangered
Species
The
Agency
has
developed
the
Endangered
Species
Protection
Program
to
identify
pesticides
whose
use
may
cause
adverse
impacts
on
endangered
and
threatened
species,
and
to
implement
mitigation
measures
that
address
these
impacts.
The
Endangered
Species
Act
requires
federal
agencies
to
ensure
that
their
actions
are
not
likely
to
jeopardize
listed
species
or
adversely
modify
designated
critical
habitat.
To
analyze
the
potential
of
registered
pesticide
uses
to
affect
any
particular
species,
EPA
puts
basic
toxicity
and
exposure
data
developed
for
REDs
into
context
for
individual
listed
species
and
their
locations
by
evaluating
important
ecological
parameters,
pesticide
use
information,
the
geographic
relationship
between
specific
pesticide
uses
and
species
locations,
and
biological
requirements
and
behavioral
aspects
of
the
particular
species.
This
analysis
will
take
into
consideration
any
regulatory
changes
recommended
in
this
RED
that
are
being
implemented
at
this
time.
A
determination
that
there
is
a
likelihood
of
potential
impact
to
a
listed
species
may
result
in
limitations
on
use
of
the
pesticide,
other
measures
to
mitigate
any
potential
impact,
or
consultations
with
the
Fish
and
Wildlife
Service
and/
or
the
National
Marine
Fisheries
Service
as
necessary.

The
Endangered
Species
Protection
Program
as
described
in
a
Federal
Register
notice
(
54
FR
27984­
28008,
July
3,
1989)
is
currently
being
implemented
on
an
interim
basis.
As
part
of
the
interim
program,
the
Agency
has
developed
County
Specific
Pamphlets
that
articulate
many
of
the
specific
measures
outlined
in
the
Biological
Opinions
issued
to
date.
The
Pamphlets
are
available
for
voluntary
use
by
pesticide
applicators
on
EPA's
website
at
www.
epa.
gov/
espp.
A
final
Endangered
Species
Protection
Program,
which
may
be
altered
from
the
interim
program,
is
scheduled
to
be
proposed
for
public
comment
in
the
Federal
Register
before
the
end
of
2001.

Endocrine
Disruption
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
the
recommendations
of
its
Endocrine
Disruptor
Screening
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
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).
4
When
the
appropriate
screening
and
or
testing
protocols
being
considered
under
the
Agency's
Endocrine
Disruptor
Screening
Program
have
been
developed,
oxadiazon,
may
be
subjected
to
additional
screening
and
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.
Issues
that
have
raised
this
concern
include
fish
reproduction
effects
(
larval
and
embryo
survival,
egg
hatchability)
and
invertebrate
reproduction
effects
(
reduced
neonate
production)
also
suggest
endocrine
disruption.

Uncertainties
Environmental
Fate
and
Exposure:

There
is
some
uncertainty
in
using
the
FIRST
and
GENEEC2
models
respectively
for
drinking
water
and
aquatic
assessment.
These
two
models
are
typically
used
for
Tier
I
screening
purposes
for
pesticides
applied
to
soils.
In
turf
environments,
the
fate
characteristics
and
transport
behavior
of
oxadiazon
may
be
different
than
those
in
soils.
Whether
the
difference
is
significant
is
not
known
at
the
present.
Hence,
it
is
difficult
to
estimate
the
magnitude
of
uncertainty.
The
turf
scenario
for
PRZM/
EMAMS
Tier
II
modeling
is
not
available
at
this
time
so
turf
EECs
can
not
be
further
refined..

Ecological
Effects:

Since
oxadiazon
is
a
herbicide,
there
is
a
potential
for
risk
to
nontarget
plants.
Lack
of
adequate
data
represents
an
uncertainty
with
regards
to
the
risk,
which
may
be
further
clarified
through
the
submission
of
data.

In
the
absence
of
data
on
chronic
effects
of
oxadiazon
to
estuarine
aquatic
organisms,
chronic
testing
results
from
freshwater
fish
and
invertebrates
species
were
extrapolated,
representing
an
uncertainty
which
may
be
satisfied
through
the
submission
of
appropriate
data.

The
high
persistence
and
lipophilicity
of
this
chemical
and
its
likelihood
to
accumulate
in
the
sediment
suggest
that
there
may
be
risk
to
benthic
and
epibenthic
aquatic
life
(
fish
and
aquatic
invertebrates).
However
the
potential
for
risk
cannot
be
further
refined
until
additional
data
(
sediment
toxicity
tests)
have
been
submitted.

Enhanced
toxicity
of
oxadiazon
to
aquatic
organisms
after
light
exposure
is
an
uncertainty.
The
inhibition
of
protoporphyrinogen
oxidase,
the
rapid
accumulation
of
protoporphyrin
IX
with
the
resulting
generation
of
singlet
oxygen
(
free
radicals)
and
eventual
cell
membrane
destruction
suggest
that
exposure
to
this
compound
may
increase
toxicity
to
aquatic
organisms
Label
Recommendations:

EFED
recommends
that
the
labels
for
all
oxadiazon
products
carry
the
following
statements:
5
Environmental
Hazards
i.
Manufacturing
Use
Product:

This
pesticide
is
toxic
to
fish
and
aquatic
invertebrates.
Do
not
discharge
effluent
containing
this
product
into
lakes,
streams,
ponds,
estuaries,
oceans,
or
other
waters
unless
in
accordance
with
the
requirements
of
a
National
Pollutant
Discharge
Elimination
System
(
NPDES)
permit
and
the
permitting
authority
has
been
notified
in
writing
prior
to
discharge.
For
guidance,
contact
your
State
Water
Board
or
Regional
Office
of
the
EPA.

ii.
End­
Use
Product:

This
pesticide
is
toxic
to
fish
and
aquatic
invertebrates.
Do
not
apply
directly
to
water,
or
to
areas
where
surface
water
is
present,
or
to
intertidal
areas
below
the
mean
high
water
mark.
Do
not
contaminate
water
when
disposing
of
equipment
washwaters
or
rinsate.
Do
not
apply
when
weather
conditions
favor
drift
from
treated
areas.
Runoff
and
drift
from
treated
areas
may
be
hazardous
to
aquatic
organisms
in
neighboring
areas.
Do
not
allow
this
product
to
drift.
6
SUPPLEMENT
Possible
Risk
Mitigation
Measures:

To
reduce
risk
to
plants
and
aquatic
organisms,
possible
risk
mitigation
measures
may
include,
but
are
not
limited
to:

The
addition
of
a
well
maintained
buffer
zone
can
also
mitigate
the
risk.
It
is
known
that
buffer
zones
can
decrease
the
amount
of
spray
drift
reaching
bodies
of
water.

The
current
label
suggests
that
to
improve
the
efficacy,
prior
to
application,
the
turf
should
be
mowed
and
after
application
it
should
be
irrigated
if
rain
is
not
expected
shortly.
Making
this
suggestion
compulsory
would
assure
that
most
of
the
chemical
reaches
the
soil
surface,
where
it
is
less
prone
to
runoff.
7
N
N
O
Cl
Cl
O
CH
O
C
CH
3
CH
3
CH
3
C
H
3
C
H
3
Environmental
Fate
and
Ecological
Risk
Assessment
for
the
Reregistration
Eligibility
Decision
Oxadiazon;
Ronstar
®
2­
tert­
Butyl­
4­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
delta2­
1,3,4­
oxadiazoline­
5­
one
and
3­[
2,4­
Dichloro­
5­(
1­
methylethoxy)
phenyl]­
5­(
1,1­
dimethyl­
ethyl)­
1,3,4­
oxadiazol­
2(
3H)­
one
Shaughnessy
Number:
109001
CAS
Number:
19666­
30­
9
Prepared
by:
Miachel
Rexrode,
Ph.
D.
José
L.
Meléndez
Environmental
Risk
Branch
V
Reviewed
by:
Environmental
Fate
and
Effects
Division
Rodolfo
Pisigan
Jr.,
Ph.
D.
Mah
T.
Shamim,
Ph.
D.
8
TABLE
OF
CONTENTS
CHAPTER
1:
ENVIRONMENTAL
RISK
CONCLUSIONS
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9
CHAPTER
2:
INTRODUCTION
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12
CHAPTER
3:
INTEGRATED
ENVIRONMENTAL
RISK
CHARACTERIZATION
.
.
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15
CHAPTER
4:
ENVIRONMENTAL
FATE
AND
TRANSPORT
ASSESSMENT
.
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19
CHAPTER
5:
DRINKING
WATER
ASSESSMENT
.
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20
CHAPTER
6:
AQUATIC
EXPOSURE
AND
RISK
ASSESSMENT
.
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21
CHAPTER
7:
TERRESTRIAL
EXPOSURE
AND
RISK
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26
CONCLUSIONS.........................................................................................................................................
32
APPENDIX
A:
REFERENCES
CITED
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33
APPENDIX
B:
FATE
SUMMARIES
.
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37
APPENDIX
C:
ECOLOGICAL
TOXICITY
DATA
.
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43
APPENDIX
D:
FATE
TERRESTRIAL
MODEL
RUNS
.
.
.
.
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.
53
APPENDIX
E:
DRINKING
WATER
CONCENTRATIONS
.
.
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60
APPENDIX
F:
EXPOSURE
AND
RISK
CHARACTERIZATION
.
.
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.
64
APPENDIX
G:
ENVIRONMENTAL
FATE
AND
ECOLOGICAL
EFFECTS
DATA
REQUIREMENTS
.
.
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69
APPENDIX
H:
QUALITATIVE
USE
ASSESSMENT
.
.
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73
APPENDIX
I:
GENEEC
2.0
INPUT
PARAMETERS,
RESULTS,
AND
OUTPUTS
.
.
.
.
.
.
.
.
.
.
.
.
.
75
APPENDIX
J:
REQUEST
for
PHOTOTOXICITY
STUDY
PROTOCOL
for
LIGHT­
DEPENDENT
PEROXIDIZING
HERBICIDES...........................................................................................
80
ATTACHMENT
I........................................................................................................................................
83
9
CHAPTER
1:
ENVIRONMENTAL
RISK
CONCLUSIONS
a.
Registered
Uses
Oxadiazon
is
a
selective
pre­
emergent
and
early
post­
emergent
herbicide
used
to
control
grassy
and
broadleaf
weeds
in
turf
and
ornamentals.
Application
rates
range
from
2
to
4
lbs
ai/
A,
with
usually
only
one
application
made
per
season.
Most
of
the
products
are
in
granular
form.
The
herbicide's
primary
use
is
on
golf
courses,
turf
farms
and
ornamental
plantings.
The
registrant,
Aventis,
is
supporting
a
maximum
yearly
use
of
eight
pounds
of
active
ingredient
per
acre.
Aerial
applications
are
not
being
supported
(
SRRD
communication).
.
Table
1.
Oxadiazon
Registered
Use
on
Turf
(
Golf
Courses),
Nursery
and
Roadsides.

Usage
Maximum
Application
Rate
(
lbs
ai/
A)
Number
of
Applications
Minimum
Application
Interval
(
days)
Maximum
Application
Rate
per
Season
(
lbs
ai/
A)

Turf
(
Ground
Spray)
4.0
2
182
8.0
4.0
1
NA
4.0
3.0
1
NA
3.0
2.0
1
NA
2.0
Turf
(
Ground
Spray)
Split
Application
1.0
8
42
8.0
1.3
6
56
8.0
Turf
(
Granular)
4.0
2
182
8.0
4.0
1
NA
4.0
3.0
1
NA
3.0
2.0
1
NA
2.0
b.
Major
Risk
Concerns
Our
assessment
shows
that
oxadiazon
exposure
in
the
aquatic
environment
can
present
significant
chronic
risk
to
freshwater
fish
and
aquatic
invertebrates.
The
chronic
Level
of
Concern
(
LOC)
was
exceeded
by
up
to
132­
fold
for
fish
and
37­
fold
for
aquatic
invertebrates.
Although
this
Tier
I
risk
assessment
suggests
that
acute
exposure
of
oxadiazon
to
aquatic
systems
should
result
in
relatively
lower
short
term
risk
to
non
endangered
fish
and
aquatic
invertebrates
there
is
uncertainty
regarding
possible
phototoxicity.
Since
oxadiazon
is
an
LDPH
compound,
enhanced
toxicity
through
exposure
to
high
levels
of
solar
radiation
is
a
possible
concern
that
could
impact
aquatic
organisms
that
inhabit
small,
shallow
water
bodies.
Oxadiazon
is
also
a
lipophilic
compound
that
has
the
capacity
to
strongly
bind
to
particulates
and
organic
carbon.
This
binding
can
result
in
accumulation
in
the
sediment
raising
concerns
for
toxic
risk
to
benthic
and
epibenthic
aquatic
organisms
(
aquatic
insects,
amphipods,
crustaceans,
mollusks,
bivalves,
10
etc).
Since
sediment
act
as
a
reservoir
for
lipophilic
persistent
compounds,
sediment
bound
oxadiazon
presents
a
high
risk
potential
for
aquatic
life
because
of
direct
contact
with
various
organisms
through
respiration,
ingestion,
dermal
contact,
or
indirectly
through
alterations
of
the
food
chain.
The
herbicidal
properties
of
this
compound
also
strongly
suggest
that
there
is
a
potential
for
toxic
risk
to
aquatic
plants
(
monocots
and
dicots)
which
may
result
in
an
indirect
impact
on
aquatic
systems
through
habitat
alteration.
Endangered
species
concerns
have
also
been
triggered
for
fish,
aquatic
invertebrates
and
plants.

Terrestrial
exposure
of
this
compound
to
mammals
and
birds
can
result
in
potential
chronic
risk
while
the
acute
risk
to
terrestrial
organisms
(
birds,
mammals,
and
honey
bees)
from
the
registered
use
of
oxadiazon
appears
low.
However,
information
on
the
herbicidal
mode
of
action
of
oxadiazon
strongly
suggests
that
there
is
a
potential
for
acute
risk
to
nontarget
aquatic
and
terrestrial
plants.
The
limited
plant
data
for
oxadiazon
shows
that
this
compound
can
present
a
toxic
risk
to
nontarget
plants
(
EC
25
values
reported
in
the
seedling
emergence/
vegetative
vigor
tests
were
as
low
as
about
a
tenth
of
a
pound
per
acre).
Although
there
does
not
appear
to
be
an
acute
risk
to
endangered
birds
and
mammals
there
may
be
chronic
concerns
as
reflected
in
the
two­
fold
LOC
exceedences
for
non
endangered
terrestrial
animals.
Therefore,
our
assessment
suggests
that
endangered
terrestrial
species
(
birds,
mammals,
and
terrestrial
plants)
may
be
at
risk.

c.
Oxadiazon
Incident
History
There
are
no
confirmed
incidents
associated
with
the
use
of
oxadiazon
in
the
Environmental
Fate
and
Effects
Division
EIIS
Database.
However,
this
data
base
is
compiled
through
voluntary
submissions
that
may
only
capture
a
small
fraction
of
actual
incidents.

d.
Likelihood
of
Water
Contamination
The
potential
impact
to
water
quality
from
the
use
of
oxadiazon
on
turf
is
essentially
due
to
the
parent
(
as
opposed
to
possible
degradates).
Oxadiazon
appears
to
be
very
persistent
under
most
environmental
conditions
making
the
chemical
available
for
surface
runoff.
Moreover,
the
remaining
important
factor
which
affects
the
impact
of
oxadiazon
on
water
quality
is
its
mobility.
A
soil
column
leaching
study,
and
supplemental
batch
equilibrium
studies
indicated
that
oxadiazon
has
low
mobility
in
the
various
soils
tested.
Ordinarily
this
would
mean
that
the
chemical
would
remain
soil
bound
and
would
be
transported
to
a
water
body
on
eroded
soil.
Turf
scenarios,
however,
offer
different
challenges
than
other
conventional
crops.
The
turf
itself
offers
a
vegetative
interception
layer
(
including
thatch)
that
prevents
rapid
deposition
of
the
oxadiazon
on
the
surface
of
the
soil.
Both
liquid
and
granular
formulations
labels
of
oxadiazon
specify
that
the
chemical's
effectiveness
is
improved
if
it
is
wetted
in
after
application.
Furthermore,
both
labels
recommend
mowing
the
grass
prior
to
application.
Oxadiazon
is
expected
to
bind
to
soil
particles,
but
turf
scenarios
offer
vegetation
interception.

The
models
used
for
the
determination
of
the
water
exposures
were
FIRST,
GENEEC
2.0
for
surface
waters,
and
SCIGROW
for
ground
waters.
The
models
are
screening
models
designed
to
provide
upper­
bound
estimates
of
the
concentrations
that
might
be
found
due
to
the
use
of
oxadiazon.
For
drinking
water
worst
case
scenario
(
4
lb
a.
i./
A
applied
at
6­
months
interval)
was
used.
Further
refinements
of
our
11
computer
models
were
not
possible
at
this
time.
The
EFED
is
currently
developing
a
turf
scenario,
which
is
expected
to
be
ready
in
the
near
future.
Surface
water
monitoring
data
for
oxadiazon
is
very
limited
and
cannot
be
used
to
represent
possible
concentrations
of
oxadiazon
in
surface
waters.
The
chemical
is
not
included
in
the
NAWQA
monitoring
studies.
The
STORET
database
contained
only
two
samples
taken
from
the
same
location
within
an
interval
of
only
four
days.
The
estimated
recommended
acute,
and
long
term
drinking
water
concentrations
are
detailed
in
Chapter
6.

Oxadiazon
has
a
high
affinity
to
soils
and
sediments
K
OC

2357,
combined
with
the
high
persistence
exhibited
in
the
aerobic
soil
metabolism
(>>
1year),
as
well
as
the
anaerobic
aquatic
metabolism
(

1
year
studies).
It
appeared
that
oxadiazon
would
be
a
persistent
chemical
in
sediment
environments.

Although
oxadiazon
exhibits
high
affinity
to
soils
and
a
relatively
high
bioconcentration
factor
(
K
ow
=
63100;
BCF's
of
368X,
2239X,
and
1111X
for
muscle,
viscera,
and
whole
fish,
respectively),
the
rate
of
depuration
was
relatively
rapid
(
half­
life
of
about
one
day).

e.
Recommended
Drinking
Water
Concentrations
for
HED
As
per
HED's
request,
the
drinking
water
assessment
for
oxadiazon
is
as
follows:
the
peak
untreated
surface
water
concentration
is
246
ppb,
and
the
annual
average
untreated
water
concentration
is
100
ppb
.
These
values
represent
upper­
bound
estimates
of
the
concentrations
of
oxadiazon
that
might
be
found
in
surface
water
due
to
the
use
of
oxadiazon
on
turf
at
the
maximum
application
rate
of
8.0
lb
a.
i./
A/
season.
The
recommended
oxadiazon
ground
water
concentration
is
0.6
ppb.

Recently
EFED
validated
a
new
turf
scenario
that
can
be
used
to
model
golf
courses.
Additionally,
new
PCA's
have
been
developed
for
golf
courses
(
tees,
greens
and
fairways).
EFED
will
model
Tier
II
drinking
water
concentrations
accordingly.
These
calculations
will
be
performed
during
the
revisions
of
the
60­
days
comments
period.

f.
Monitoring
and
Modeling
As
shown
in
Table
3,
the
groundwater
concentration
estimated
from
SCIGROW
is
0.6
ppb
which
is
about
two
orders
of
magnitude
lower
than
those
of
surface
water.
This
concentration
may
be
used
for
both
acute
and
chronic
values.
The
low
concentration
is
consistent
with
both
laboratory
and
field
studies
that
indicate
the
low
mobility
of
oxadiazon,
and
subsequently,
its
reduced
potential
to
reach
groundwater.
12
CHAPTER
2:
INTRODUCTION
a.
Mode
of
Action
Oxadiazon
is
a
selective
pre­
emergent
and
early
post­
emergent
herbicide
used
to
control
grassy
weeds
(
e.
g.,
crabgrass
and
goosegrass)
and
broadleaf
weeds.
The
primary
mode
of
action
of
oxadiazon
is
inhibition
of
protoporphyrinogen
oxidase
(
Protex),
a
critical
enzyme
in
the
biosynthesis
of
chlorophyll
and
heme
(
Matringe
et
al.,
1989).
Consistent
with
protoporphyrinogen
oxidase­
inhibiting
herbicides,
tissue
exposed
in
darkness
accumulate
protoporphyrin
IX,
which
can
lead
to
a
photodynamic
loss
of
cell
membrane
integrity
(
free
radical
development)
upon
exposure
to
light.

b.
Use
Characterization
The
formulation
types
include
granular
(
39
products;
predominant
formulation),
wettable
powder
(
2
products),
soluble
concentrate
(
1
product)
and
emulsifiable
concentrate
(
1
product).
Aventis
is
the
sole
technical
registrant.
Oxadiazon
is
registered
for
use
on
terrestrial
non­
food
crop
sites,
including
golf
courses;
landscape
(
turf
and
ornamentals);
nursery;
and
roadside.

An
annual
estimate
of
oxadiazon's
total
usage
is
249,000
pounds
of
active
ingredient
on
52,000
acres.
Most
of
the
use
is
on
golf
courses,
which
accounts
for
about
65%
of
all
use.
Application
rates
range
from
two
to
four
pounds
active
ingredient
per
acre.
According
to
SRRD,
Aventis
is
supporting
a
maximum
application
of
4.0
lb
ai/
A
per
six
month
period,
equivalent
to
8.0
lbs
ai/
year
and
aerial
applications
are
not
being
supported.
Since
efficacy
(
pre
emergent
control)
is
based
on
oxadiazon
reaching
and
remaining
in
the
soil,
product
labels
may
specify
to
mow,
if
necessary,
before
application,
and
to
irrigate,
if
rain
is
not
expected
shortly.
Oxadiazon
may
also
be
used
for
early
post­
emergent
control,
but
this
is
to
a
much
lesser
extent.
(
usage
information
was
obtained
from
BEAD's
Qualitative
Use
Assessment,
Appendix
K).

Oxadiazon
is
classified
as
an
oxadiazole
herbicide.
The
chemical
name
is:
5­
tert­
Butyl­
3­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
1,3,4­
oxadiazol­
2(
3H)­
one.
Other
chemical
names
are:
(
IUPAC).
2­
tert­
Butyl­
4­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
delta2­
1,3,4­
oxadiazoline­
5­
one
and
3­[
2,4­
Dichloro­
5­(
1­
methylethoxy)
phenyl]­
5­(
1,1­
dimethyl­
ethyl)­
1,3,4­
oxadiazol­
2(
3H)­
one.
Trade
names
include
Ronstar,
RP­
17623,
and
G
315.

c.
Approach
to
Risk
Assessment
In
order
to
conduct
an
ecological
risk
assessments
on
this
compound,
EFED
used
dosage
rate
information
obtained
from
SRRD
and
BEAD.
The
evaluation
of
the
potential
risk
to
aquatic
and
terrestrial
organisms
from
the
use
of
oxadiazon,
was
assessed
through
the
calculation
of
risk
quotients
(
RQs)
that
were
derived
from
the
ratio
of
estimated
environmental
concentrations
(
EECs)
to
ecotoxicity
values
(
see
Appendix
F).
EECs
were
based
on
the
maximum
and
typical
application
rate
of
oxadiazon
to
turf.
These
RQs
are
then
compared
to
the
Levels
of
Concern
(
LOC)
(
Appendix
F)
criteria
used
by
EFED
for
determining
potential
risk
to
nontarget
organisms
and
the
subsequent
need
for
possible
regulatory
action.
1EFED
examined
two
DER's
that
provide
data
(
2­
7
day
half­
life)
on
the
decay
of
transferable
residues
of
oxadiazon
from
turf
surfaces
to
a
cotton
cloth,
EFED
chose
not
to
use
these
studies
because
one
study
was
conducted
on
a
granular
formulation
and
the
other
study
presented
a
quantitative
concern.

13
Terrestrial
exposure
was
evaluated
using
EECs
generated
from
ELL­
FATE
spreadsheet­
based
model
that
calculates
the
decay
of
a
chemical
applied
to
foliar
surfaces
for
single
and
multiple
applications.
The
model
assumes
initial
concentrations
on
plant
surfaces
based
on
Kenaga
predicted
maximum
residues
as
modified
by
Fletcher
et
al.
(
1994)
and
assumes
1st
order
dissipation.
Kenaga
estimates
and
an
explanation
of
the
model
with
sample
output
are
presented
in
Appendix
F.
In
the
absence
of
foliar
dissipation
half­
life
data
for
oxadiazon
a
35­
day
half­
life
was
used.
The
selection
of
this
half­
life
was
based
on
the
upper
limit
of
pesticide,
foliar
dissipation
half­
lives
provided
in
the
half­
life
listing
of
Willis
and
McDowell,
1987.
EFED
uses
this
value
as
a
default
equivalent
when
the
foliar
dissipation
for
a
particular
pesticide
is
unknown
or
in
question1.
The
terrestrial
and
aquatic
risk
assessment
was
also
based
on
the
three
maximum
application
rates
of
4.0,
3.0,
and
2.0
lbs
ai/
A
at
2
applications
each
and
a
4.0
lbs
ai/
A
for
granular,
at
2
applications.
Additional
exposure
scenarios
for
split
application
(
1.0
and
1.3
lbs
ai/
A,
at
6
and
8
week
intervals,
respectively)
were
conducted
for
terrestrial
exposure.
Aquatic
exposure
was
evaluated
using
EECs
generated
from
the
Tier
I
GENEEC2
model.
14
Aquatic
and
terrestrial
risk
assessments
were
conducted
by
using
worst
case
ecotoxicity
endpoints
(
i.
e.,
LD50
and
LC50
values,
NOAEC
values).
The
toxicity
endpoints
chosen
for
use
in
the
ecological
risk
assessment
are
summarized
below.

Table
2.
Selection
of
Toxicological
Endpoints
Used
to
Determine
Risk
Quotients
(
RQs)

Type
Of
Toxicity
Organism
Species
Toxicological
Endpoint
Oral
Acute
Bird
Mallard
1040
mg/
kg
Dietary
Bobwhite/
Mallard
>
5000
ppm
Chronic
Bobwhite
500
ppm
1
Oral
Acute
Mammal
Rat
>
5000
mg/
kg
Chronic
Rat
200
ppm
2
Acute
Freshwater
Fish
Rainbow
trout/
Bluegill
0.88
ppm
Chronic
Rainbow
trout
0.88
ppb
3
Acute
Freshwater
Invertebrates
Daphnid
2.18
ppm
Chronic
Daphnid
0.03
ppm
Acute
Estuarine
Fish
Sheepshead
Minnow
1.5
ppm
Chronic
Sheepshead
Minnow
0.0015
ppm
4
Acute
Estuarine
Invertebrates
Mysid
0.27
ppm
Chronic
Mysid
0.0037ppm4
Acute
Aquatic
Plants
(
vascular)

(
Nonvascular)
duckweed
marine
diatom
EC50
=
41
ppb;
NOAEC
=
<
8
ppb
EC50
=
5.2
ppb
1
No
effects
on
any
reproductive
parameter
or
viability
of
of
F1
offspring
at
the
highest
dose
tested,
1000
ppm;
however
due
to
excessive
mortality
(
33%)
of
adult
female
birds
in
that
dose
level,
a
NOAEC
for
chronic
effects
was
set
at
500
ppm.
2
LOAEL
of
>
38
mg/
kg/
day
for
inactive
mammary
tissue
and
fetal/
pup
death
observed
in
the
one
year
range­
finding
test
of
a
rat
reproduction
study.
NOAEC
>
200
ppm.
3
Rainbow
trout
was
more
sensitive
than
the
fathead
minnow
(
fathead
minnow
NOAEC=
33
ppb).
4
Extrapolation
from
acute/
chronic
ratio.
15
CHAPTER
3:
INTEGRATED
ENVIRONMENTAL
RISK
CHARACTERIZATION
Oxadiazon
is
a
persistent,
lipophilic
compound
that
has
low
mobility
in
most
soils
(
not
expected
to
move
to
ground
water),
and
may
be
susceptible
to
aqueous
photolysis.
Oxadiazon
is
also
a
light­
dependent
peroxidizing
herbicide
(
LDPH)
that
has
the
potential
for
the
induction
of
phototoxicity
(
exposure
to
light
results
in
the
development
of
free
radicals
that
can
destroy
cell
membranes).
Our
risk
assessment
shows
that
chronic
exposure
of
this
compound
to
aquatic
organisms
(
estuarine/
marine
fish
and
aquatic
invertebrates)
can
result
in
significant
reproductive
effects
(
EFED's
runoff
and
drift
exposure
scenarios).
Aquatic
risk
is
further
compounded
by
oxadiazon's
ability
to
bind
and
accumulate
in
the
sediment.
As
a
contrast,
terrestrial
concerns
for
this
compound
are
mixed.
The
potential
for
chronic
risk
to
mammals
appears
very
high
and
could
result
in
significant
reproductive
effects.
However,
chronic
risk
to
birds
appeared
to
be
a
relatively
lower
concern
although
values
still
exceed
EFED's
level
of
concern
(
LOC).
Our
analysis
also
noted
that
acute
exposure
of
oxadiazon
(
emulsifiable
concentrate
and
granular)
to
birds
and
mammals
should
not
present
significant
short
term
toxic
risk.
EFED
also
has
a
concern
that
exposure
of
oxadiazon
to
aquatic
and
terrestrial
systems
may
result
in
a
potential
risk
to
endangered
species
that
can
include
mammals,
birds,
fish
and
aquatic
invertebrates.
Since
this
compound
is
a
herbicide,
there
is
the
potential
for
impact
to
nontarget
plants
(
terrestrial,
semi­
aquatic
and
aquatic).
However,
this
possible
risk
to
nontarget
plants
cannot
be
fully
assessed
at
this
time
due
to
the
lack
of
acceptable
data.

The
focus
of
this
risk
assessment
is
based
on
toxicity
and
exposure
values
(
risk
quotients
or
RQs
as
the
ratio
of
exposure/
toxicity),
the
disposition
(
fate)
of
oxadiazon
in
the
environment,
and
its
mode
of
action
as
a
phototoxic
compound.
In
order
to
evaluate
the
potential
for
risk
to
non
target
organisms,
our
assessment
is
divided
into
aquatic
and
terrestrial
exposure
scenarios.
The
aquatic
component
was
evaluated
through
GENEEC2
pond
scenario
while
terrestrial
impact
was
assessed
through
the
ELL­
FATE
model.
Since
oxadiazon
is
primarly
used
as
a
herbicide
on
turf,
especially
golf
courses,
EFED
has
evaluated
the
proximity
of
these
areas
to
estuarine/
marine
environments,
and
the
ecological
significance
of
application
timing.

Oxadiazon
is
a
stable
and
persistent
compound.
However,
direct
aqueous
photolysis
half­
life
of
about
3
days
suggests
that
in
clear
and
shallow
surface
water
bodies
where
sunlight
penetration
can
be
significant,
photolytic
degradation
of
oxadiazon
is
possible.
However,
this
photolytic
effect
may
also
substantially
diminish
in
turbid
and
deeper
water
bodies.
Soil
photolysis
and
hydrolysis
under
acidic
and
basic
conditions
do
not
appear
to
be
an
important
dissipation
mechanism.
Microbial
metabolism
in
soil
and
aquatic
environments
under
either
aerobic
and
anaerobic
condition
is
not
expected
to
cause
any
significant
transformation
of
oxadiazon.
Studies
on
equilibrium
sorption
and
aged/
unaged
oxadiazon
indicate
that
the
pesticide
has
low
environmental
mobility
(
K
d's
ranged
from
8.17
to
22.83;
K
oc's
ranged
from
1409
to
3268).
Thus,
oxadiazon
can
be
transported
on
erodible
soil
particles
via
runoff
events
to
nearby
surface
water
bodies.
Leaching
from
surficial
soils
to
groundwater
is
expected
to
be
low
or
negligible,
unless
the
soil
is
very
porous
or
has
some
cracks
that
favor
preferential
flow.
Oxadiazon
exhibited
slow
dissipation
in
two
field
terrestrial
studies
conducted
in
California
and
North
Carolina.

Our
review
has
found
that
golf
courses
can
represent
about
2,300,000
acres
in
the
USA.
About
half
of
this
acreage
is
located
in
counties
that
are
considered
coastal
and
close
to
estuarine/
marine
environments
16
and
tributaries.
Because
of
the
proximity
to
these
aquatic
habitats
to
golf
courses,
EFED
has
a
concern
for
any
persistent
compound
that
has
the
potential
for
runoff
and
toxicity
to
aquatic
systems
that
include
estuaries.
Many
of
these
aquatic
areas
have
significant
fisheries
that
can
account
for
over
65%
of
the
commercial
catches
for
the
USA.
(
e.
g.
Chesapeake
Bay,
Long
Island
Sound,
The
Gulf
of
Mexico,
San
Diego
Bay,
San
Francisco
Bay,
Puget
Sound,
etc.).
Impact
to
this
resource
could
effect
not
only
the
ecological
value
but
the
livelihood
of
fishing
communities
and
markets
at
a
local
and
national
level.

Since
oxadiazon
is
stable
to
hydrolysis
and
persistent
in
the
environment,
the
results
from
our
Tier
I
(
GENEEC2)
pond
scenario
model
suggest
that
chronic
exposure
of
oxadiazon
can
result
in
significant
long
term
risk
to
freshwater
and
estuarine/
marine
fish
and
aquatic
invertebrates.
Our
screening
level
assessment
shows
that
the
RQ
values
that
were
generated
exceeded
the
LOC
by
significant
amounts
of
4
­
132
fold
(
application
rates
of
2.0
­
4.0
lbs
ai/
A
EC
and
granular
formulation).
The
issue
of
chronic
toxicity
is
compounded
by
the
lipophilic
nature
of
oxadiazon.
Since
this
stable
compound
can
be
absorbed
to
particulate
and
organic
carbon,
oxadiazon
residues
can
accumulate
in
sediments
and
increase
the
potential
for
chronic
risk
to
benthic
and
epibenthic
organisms
(
aquatic
organisms
that
live
in
or
on
the
sediment).
Acting
as
a
repository
for
lipophilic
compounds,
sediments
can
impact
aquatic
organisms
through
respiration,
ingestion,
dermal
contact,
and/
or
indirect
impact
through
alterations
of
the
food
chain.
This
can
present
a
significant
risk
to
aquatic
organisms
because
about
80%
of
all
aquatic
life
in
estuaries
is
in
contact
with
the
benthos.
Therefore,
in
order
to
better
understand
this
potential
risk,
EFED
is
requiring
appropriate
sediment
toxicity
testing
(
acute
and
chronic)
on
this
compound.
Another
issue
of
concern
is
the
uncertainty
regarding
the
degree
of
phototoxicity
of
this
compound
to
aquatic
organisms.
Since
oxadiazon
is
a
lightdependent
peroxidizing
herbicide
(
LDPH),
enhanced
toxicity
through
exposure
to
high
levels
of
solar
radiation
may
increase
toxic
risk
to
aquatic
organisms
that
inhabit
small,
shallow
water
bodies
(
toxicity
is
increased
through
the
production
of
free
radicals
which
actively
destroy
cell
membranes).
This
can
be
very
critical
to
several
species
of
aquatic
organisms
(
fish,
crabs,
etc)
whose
early
life
stages
are
dependent
upon
these
relatively
shallow
areas
for
their
development.
The
herbicidal
properties
of
oxadiazon
also
suggest
the
potential
for
acute
toxicity
to
aquatic
plants
and
the
possibility
of
aquatic
habitats
alterations.
This
can
potentiate
an
indirect
effect
to
aquatic
populations
through
a
decrease
in
plant
cover.
In
addition
to
toxic
risk
to
non
target
aquatic
organisms,
oxadiazon
may
also
impact
endangered
species
(
fish
and
invertebrates).

The
potential
for
birds
and
mammals
to
be
exposed
to
pesticides
through
a
turf
use
has
been
documented
(
e.
g.
chlorpyrifos,
lindane).
The
application
of
oxadiazon
in
the
spring
as
noted
from
the
label,
can
coincide
with
several
avian
and
mammalian
reproductive
cycles,
as
well
as
spring
migrations
(
avian).
In
order
to
evaluate
the
potential
for
risk
to
terrestrial
organisms,
EFED
has
conducted
a
Tier
I
assessment
by
using
the
ELL­
FATE
model.
In
order
to
evaluate
possible
toxic
risk
to
terrestrial
organisms,
three
application
rates
(
4.0,
3.0,
and
2.0
lbs
ai/
A,
at
2
applications/
6
months)
and
two
split
applications
(
1.0
lbs
ai/
A
applied
4
times/
6
month
and
1.3
lbs
ai/
A
applied
3
times/
6
month)
were
run.
Our
objective
was
to
find
not
only
the
highest
rate
that
may
cause
toxic
risk,
but
the
rate
that
might
result
in
lower
risk.
Our
assessment
noted
that
acute
risk
to
birds
and
mammals
was
minimal
and
should
not
present
any
short
term
toxic
concern
to
these
organisms.
However,
all
application
scenarios
showed
that
chronic
exposure
could
result
in
significant
risk
to
mammalian
herbivores
and
insectivores
(
15g,
35g,
and
1000g)
with
RQ
exceedences
of
1.5
­
9.9
fold.
In
contrast
to
mammalian
chronic
risk,
our
assessment
also
noted
that
17
chronic
exposure
to
birds
could
result
in
relatively
lower
RQ
values
that
showed
exceedence
of
about
1
to
2
fold
the
LOC.
This
could
be
interpreted
as
potentially
low
toxic
risk
(
chronic)
to
birds
that
feed
on
plants
and
grass
(
e.
g.
ducks,
geese).
A
reduction
in
chronic
risk
to
birds
was
noted
with
the
split
application
scenarios
(
RQ
=
<
1),
but
chronic
risk
to
mammals
was
still
very
high
even
with
this
scenario.
Exposure
from
the
granular
formulation
was
evaluated
because
birds
may
be
exposed
to
granular
pesticides
through
ingestion
when
foraging
for
food
or
grit.
RQ
values
were
calculated
for
three
weight
classes
of
birds
(
1000g
waterfowl,
180g
upland
game
bird,
and
20g
songbird).
All
scenarios
for
the
granular
resulted
in
no
acute
risk
to
birds
(
EFED
does
not
conduct
a
chronic
assessment
from
granular
exposure).

The
potential
for
chronic
risk
(
high
for
mammals
but
relatively
low
for
birds)
that
has
been
noted
for
terrestrial
organisms
suggests
that
oxadiazon
may
present
a
risk
to
both
avian
and
mammalian
endangered
species
(
RQ
>
0.1),
even
though
the
acute
LOC
values
were
not
exceeded.
Although,
risk
to
terrestrial
plants
could
not
be
conducted
at
this
time
(
lack
of
data),
oxadiaxon's
herbicidal
mode
of
action
suggests
that
there
is
a
potential
for
risk
to
nontarget
terrestrial
plants,
as
well
as
endangered
plants.
Since
oxadiazon
is
practically
non­
toxic
to
the
honey
bee,
minimal
risk
to
these
organisms
is
anticipated.

The
Agency
is
currently
engaged
in
a
Proactive
Conservation
Review
with
FWS
and
the
National
Marine
Fisheries
Service
under
section
7(
a)(
1)
of
the
Endangered
Species
Act.
The
objective
of
this
review
is
to
clarify
and
develop
consistent
processes
for
endangered
species
risk
assessments
and
consultations.
Subsequent
to
the
completion
of
this
process,
the
Agency
will
reassess
the
potential
effects
of
oxadiazon
use
to
federally
listed
threatened
and
endangered
species.
At
that
time
the
Agency
will
also
consider
any
regulatory
changes
recommended
in
the
RED
that
are
being
implemented.
Until
such
time
as
this
analysis
is
completed,
the
overall
environmental
effects
mitigation
strategy
articulated
in
this
document
and
any
County
Specific
Pamphlets
which
address
oxadiazon,
will
serve
as
interim
protection
measures
to
reduce
the
likelihood
that
endangered
and
threatened
species
may
be
exposed
to
oxadiazon
at
levels
of
concern.
The
endangered
species
LOCs
for
liquid
and
granular
formulations
of
oxadiazon
are
exceeded
for
chronic
risks
to
birds
and
mammals
and
acute/
chronic
risk
to
freshwater
and
estuarine
fish
and
invertebrates
and
aquatic
vascular
plants.
Although
the
terrestrial
plant
data
are
outstanding,
it
is
assumed
that
endangered
terrestrial
plants
are
at
risk
since
oxadiazon
is
an
herbicide.
Although
the
endangered
species
LOC
for
estuarine
invertebrates
has
been
exceeded,
there
are
no
listed
species
in
this
group.

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
the
recommendations
of
its
Endocrine
Disruptor
Screening
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
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).
18
When
the
appropriate
screening
and
or
testing
protocols
being
considered
under
the
Agency's
Endocrine
Disruptor
Screening
Program
have
been
developed,
oxadiazon,
may
be
subjected
to
additional
screening
and
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.
Issues
that
have
raised
this
concern
include
fish
reproduction
effects
(
larval
and
embryo
survival,
egg
hatchability)
and
invertebrate
reproduction
effects
(
reduced
neonate
production).
19
CHAPTER
4:
ENVIRONMENTAL
FATE
AND
TRANSPORT
ASSESSMENT
Basic
Physicochemical
Parameters
The
important
properties
of
oxadiazon
are
summarized
below.
Oxadiazon
is
a
high­
molecularweight
compound
with
fairly
low
solubility
in
water
and
high
solubility
in
organic
solvents.
It
has
a
low
vapor
pressure
and
Henry's
Law
Constant
(<<
1
x
10­
3
atm­
m­
3/
mol)
suggesting
that
volatilization
from
soil
and
surface
water
environments
is
not
important.
Its
high
Kow
value
tends
to
indicate
that
bioconcentration
in
aquatic
organisms
such
as
fish
is
possible.
Nevertheless,
the
high
bioconcentration
factors
observed
in
studies
using
bluegill
sunfish
can
be
offset
by
fast
depuration
rate.

Molecular
formula:
C
15
H
18
Cl
2
N
2
O
3.
Molecular
weight:
345.2.
Physical
state:
Colorless
crystals.
Vapor
pressure
(
20

C):
1.00x10­
6
mm
Hg
Henry's
Constant:
4.51x10­
7
Atm$
m3/
mol
Solubility
(
20

C):
1
ppm
water
(
25

C)
600
g/
L
acetone,
acetophenone,
anisole
1
kg/
L
benzene,
chloroform,
toluene
100
g/
L
ethanol,
methanol
K
ow:
63,100
log
10
K
ow:
4.8
Fate
and
Transport
Processes
­
Summary
Based
on
fate
studies
reviewed,
oxadiazon
would
be
stable
and
persistent
under
typical
natural
environment.
However,
direct
aqueous
photolysis
half­
life
of
about
3
days
(
summer
sunlight
conditions
in
Florida)
suggests
that
in
clear
and
shallow
surface
water
bodies
where
sunlight
penetration
can
be
significant,
photolytic
degradation
of
oxadiazon
is
possible.
The
photolytic
effect
though
may
substantially
diminish
in
turbid
and
deeper
water
bodies.
Soil
photolysis
and
hydrolysis
under
acidic
and
basic
conditions
do
not
appear
to
be
an
important
dissipation
mechanism.
Microbial
metabolism
in
soil
and
aquatic
environments
under
either
aerobic
and
anaerobic
condition
is
not
expected
to
cause
any
significant
transformation
of
oxadiazon.
A
number
of
degradates
have
been
reported
from
the
different
chemical
and
biological
fate
studies.
The
nomenclature
of
these
degradates
are
summarized
in
Appendix
3
(
move
nomenclauture
on
page
to
20
to
this
Appendix
3).

Studies
on
equilibrium
sorption
and
aged/
unaged
oxadiazon
indicate
that
the
pesticide
has
low
environmental
mobility
(
K
d's
ranged
from
8.17
to
22.83;
K
oc's
ranged
from
1409
to
3268).
Thus,
oxadiazon
can
be
transported
as
sorbed
species
to
erodible
soil
particles
via
surface
runoff
to
nearby
surface
water
bodies.
Leaching
from
surficial
soils
to
groundwater
is
expected
to
be
low
or
negligible,
unless
the
soil
is
very
porous
or
has
some
cracks
that
favor
preferential
flow.
Oxadiazon
exhibited
slow
dissipation
in
two
field
terrestrial
studies
conducted
in
California
and
North
Carolina.
Details
of
all
the
fate
and
transport
studies
are
discussed
in
Appendix
B.
20
CHAPTER
5:
DRINKING
WATER
ASSESSMENT
a.
Estimated
Environmental
Concentrations
and
Drinking
Water
Concentration
Estimates
TierI
screening
models,
FIRST
and
SCIGROW,
were
used
to
determine
estimated
environmental
concentrations
(
EECs)
of
oxadiazon
in
surface
water
and
groundwater
associated
with
the
ground
spray
application
of
4.0
lbs
a.
i./
A
(
applied
two
times
a
year)
in
turf.
FIRST
estimates
surface
water
concentrations
resulting
from
runoff
of
applied
pesticides
from
a
treated
area
to
an
adjacent
index
water
reservoir
in
which
the
percent
or
fraction
of
cropped
area
(
0.87)
is
taken
into
account.
SCIGROW
predicts
groundwater
concentrations
after
leaching
of
pesticides
from
the
surficial
soils
and/
or
subsurface
horizons
to
the
aquifer.
The
screening
concentrations
derived
from
the
two
models
are
used
in
the
evaluation
of
human
exposure
to
contaminated
drinking
water.
Details
about
the
two
models,
including
the
input
parameters
and
computer
output
printouts
for
turf
scenario,
are
presented
in
Appendix
E
(
Drinking
Water
Memo).

Surface
Water
The
results
of
FIRST
modeling
for
the
acute
and
chronic
surface
water
EECs
are
summarized
in
the
table
below.
The
acute
(
246
ppb)
and
chronic
(
100
ppb)
values
represent
the
peak
and
annual
average
concentrations
predicted
by
the
model.
These
values
generally
represent
upper
bound
estimates.
The
values
are
relatively
higher
than
the
two
similar
oxadiazon
detections
(
0.05
ug/
L)
in
Larue,
KY
reported
in
the
1997
surface
water
monitoring
data
of
the
STORET
system.
Therefore,
based
on
the
data
available,
EFED
conservatively
recommends
to
use
the
model­
predicted
values
for
surface
derived
drinking
water
concentrations.

Table
3.
Estimated
Tier
I
concentrations
of
oxadiazon
in
drinking
water
Chemical
Surface
Water
(
ug/
L)
Groundwater
(
ug/
L)

Acute
Chronic
Acute
and
Chronic
Oxadiazon
246
100
0.6
Groundwater
As
shown
in
Table
3,
the
groundwater
concentration
estimated
from
SCIGROW
is
0.6
ppb
which
is
about
two
orders
of
magnitude
lower
than
those
of
surface
water.
This
concentration
may
be
used
for
both
acute
and
chronic
values.
The
low
concentration
is
consistent
with
both
laboratory
and
field
studies
that
indicate
the
low
mobility
of
oxadiazon,
and
subsequently,
its
reduced
potential
to
reach
groundwater.
21
CHAPTER
6:
AQUATIC
EXPOSURE
AND
RISK
ASSESSMENT
a.
Aquatic
(
Acute/
Chronic
Hazard
Summary)

Oxadiazon
is
considered
to
be
moderately
toxic
on
an
acute
basis
to
freshwater
fish
(
LC
50
=
0.88­
1.2
ppm)
and
estuarine/
marine
fish
(
LC
50
=
1.5
ppm).
However,
chronic
NOAEC/
LOAEC
were
determined
for
freshwater
fish
at
0.88/
1.7
ppb
with
egg
hatchability
as
the
endpoint
effected.
Oxadiazon
has
the
potential
for
high
acute
toxicity
to
estuarine/
marine
invertebrates
(
EC
50
=
0.27
­
0.7
ppb)
but
appears
to
be
moderately
toxic
to
freshwater
invertebrates
(
LC
50
=
2.18
­
2.4
ppm).
Chronic
toxicity
to
freshwater
invertebrates
shows
reproductive
effects
(
mean
time
to
first
brood,
#
young/
adult/
reproductive
day,
survival,
growth)
with
a
NOAEC/
LOAEC
=
30.0/
35.0
ppb.
The
limited
data
on
plant
toxicity
shows
that
oxadiazon
is
toxic
to
non­
vascular
aquatic
plants
(
marine
diatom
EC
50
=
5.2
ppb)
and
vascular
aquatic
plants
(
duckweed
EC
50
=
41
ppb).

b.
Risk
to
Aquatic
Organisms
(
Acute/
Chronic)

Tables
4
and
5
provide
acute
and
chronic
RQ
values
for
oxadiazon
exposure
to
freshwater
and
estuarine/
marine
species
relative
to
turf
use
patterns
(
application
rates
for
EC
at
2.0
­
4.0
lbs
ai/
A
and
4.0
lbs
ai/
A
for
granular).
Our
Tier
I
(
GENEEC)
risk
assessment
suggests
that
chronic
exposure
of
this
compound
can
result
in
significant
chronic
risk
to
freshwater
and
estuarine/
marine
fish
(
RQ
=
39.3
­
131.8)
and
aquatic
invertebrates
(
RQ
=
3.9
­
36.7).
Although
our
assessment
further
suggests
that
oxadiazon
acute
exposure
may
result
in
low
acute
risk
to
fish
(
RQ
=
0.1
­
0.2)
and
invertebrates
(
RQ
=
0.3
­
0.5),
there
is
uncertainty
regarding
the
potential
for
enhanced
risk
that
may
occur
through
phototoxicity.
Since
oxadiazon
is
a
light­
dependent
peroxidizing
herbicide
(
LDPH),
enhanced
toxicity
through
exposure
to
high
levels
of
solar
radiation
is
a
possible
concern
regarding
aquatic
organisms
that
inhabit
small,
shallow
water
bodies.
Endangered
species
concerns
are
also
suggested
with
RQ
=
0.1.

Aquatic
plant
acute
high
risk
levels
of
concern
are
exceeded
(
Table
6
and
7)
for
both
vascular
and
nonvascular
plants.
The
exceedences
range
1
­
4
fold
for
vascular
plants
and
8.5
­
33
fold
for
non­
vascular
plants.
The
acute
plant
high
risk
level
of
concern
is
exceeded
for
vascular
plants
with
an
exceedence
range
of
5.5
­
22
fold.
Currently,
EFED
does
not
perform
assessments
for
chronic
risk
to
aquatic
plants.
22
Table
4.
Acute
and
chronic
RQ's
for
evaluating
toxic
risk
of
oxadiazon
exposure
to
fish
(
freshwater
and
estuarine/
marine).
RQ's
are
based
on
the
bluegill
(
Lepomis
macrochirus)
LC50
=
0.88
ppm,
rainbow
trout
(
Oncorhynchus
mykiss)
NOAEC
=
0.00088
ppm
and
sheepshead
minnow
(
Cyprinodon
variegatus)
LC50
=
1.5
ppm.,
NOAEC
=
0.0015
ppm1.
EEC
values
are
generated
from
GENEEC
and
reflect
three
of
the
highest
proposed
EC
application
rates,
and
the
maximum
granular
use
rate
(
4.0,
3.0,
and
2.0
lbs
ai/
A,
2
applications
each;
4.0
lbs
ai/
A,
2
applications,
respectively)
for
turf
use.

Crop
App.
Rate
(
lbs
ai/
A;
#
App.)
Organism
LC50
(
ppm)
NOAEC
(
ppm)
EEC
Peak
(
ppm)
EEC
60­
Day
Ave.
(
ppm)
Acute
RQ
(
EEC/
LC50)
Chronic
RQ
(
EEC/
NOAEC)

Turf
(
EC)
4.0
(
2)
Freshwater
0.88
0.00088
0.143
0.116
0.22
131.83
Estuarine/
Marine
1.5
0.00151
0.143
0.116
0.12
77.33
Turf
(
EC)
3
(
2)
Freshwater
0.88
0.00088
0.130
0.122
0.12
139.03
Estuarine/
Marine
1.5
0.00151
0.130
0.122
0.12
81.33
Turf
(
EC)
2
(
2)
Freshwater
0.88
0.00088
0.088
0.083
0.12
94.33
Estuarine/
Marine
1.5
0.00151
0.088
0.083
0.0
55.33
Turf
(
Granular)
4.0
(
2)
Freshwater
0.88
0.00088
0.122
0.099
0.12
112.53
Estuarine/
Marine
1.5
0.00151
0.122
0.099
0.12
66.03
1
Extrapolated
chronic
value
using
acute/
chronic
freshwater
toxicity
ratio
2
Acute
restrictive
use
(>
0.1),
acute
species
3
Chronic
concern
(>
1.0)
23
Table
5.
Acute
and
chronic
risk
RQ's
for
evaluating
toxic
risk
of
oxadiazon
exposure
to
aquatic
invertebrates
(
freshwater
and
estuarine
/
marine).
RQ's
are
based
on
Daphnia
(
Daphnia
magna)
EC50
=
2.18
ppm,
NOAEC
=
0.03
ppm
and
the
Mysid
shrimp
(
Americamysis
bahia)
EC50
=
0.27
ppm,
NOAEC
=
0.0037
ppm1.
EEC
values
are
generated
from
GENEEC
and
reflect
three
of
the
highest
proposed
EC
application
rates,
and
the
maximum
granular
use
rate
(
4.0,
3.0,
and
2.0
lbs
ai/
A,
2
applications
each;
4.0
lbs
ai/
A,
2
applications,
respectively)
for
turf
use.

Crop
App.
Rate
(
lbs
ai/
A)
#
App.
(
days)
Organism
EC50
(
ppm)
NOAEC
(
ppm)
EEC
Peak
(
ppm)
EEC
21­
Day
Ave.
(
ppm)
Acute
RQ
(
EEC/
LC50)
Chronic
RQ
(
EEC/
NOAEC)

Turf
(
EC)
4.0
(
2)
Freshwater
2.18
0.03
0.143
0.136
0.12
4.51
Estuarine/
Marine
0.27
0.0037
0.143
0.136
0.52
36.71
Turf
(
EC)
3.0
(
2)
Freshwater
2.18
0.03
0.130
0.127
0.52
4.21
Estuarine/
Marine
0.27
0.0037
0.130
0.127
0.52
34.33
Turf
(
EC)
2.0
(
2)
Freshwater
2.18
0.03
0.088
0.086
0.0
2.93
Estuarine/
Marine
0.27
0.0037
0.088
0.086
0.32
23.23
Turf
(
Granular)
4.0
(
2)
Freshwater
2.18
0.03
0.122
0.116
0.0
3.91
Estuarine/
Marine
0.27
0.0037
0.122
0.116
0.42
31.31
1
Extrapolated
chronic
value
using
acute/
chronic
freshwater
toxicity
ratio
2
Acute
restrictive
use
(>
0.1)
3
Chronic
concern
(>
1.0)
24
Exposure
and
Risk
to
Aquatic
Plants
Exposure
to
nontarget
aquatic
plants
may
occur
through
runoff
or
spray
drift
from
adjacent
treated
sites.
An
aquatic
plant
risk
assessment
for
acute
high
risk
is
usually
made
for
aquatic
vascular
plants
from
the
surrogate
duckweed
Lemna
gibba.
Non­
vascular
acute
high
aquatic
plant
risk
assessments
are
performed
using
either
algae
or
a
diatom,
whichever
is
the
most
sensitive
species.
Runoff
and
drift
exposure
are
computed
from
GENEEC2
and
the
risk
quotient
is
determined
by
dividing
the
pesticide's
initial
or
peak
concentration
in
water
by
the
plant
EC
50
value.
Acute
risk
quotients
for
vascular
and
non­
vascular
plants
are
tabulated
in
Table
6.

Table
6.
Acute
Risk
Quotients
for
Aquatic
Plants
based
upon
a
duckweed
(
Lemna
gibba)
EC50
of
41
ppb
and
a
nonvascular
plant
(
marine
diatom)
EC50
of
5.2
ppb.

Turf/
Rate
of
Application
in
lbs
ai/
A
(
Number
of
Applications).
Species
EC50
(
ppm)
EEC
(
ppm)
Non­
target
plant
RQ
(
EEC/
EC50)

4
(
1)
duckweed
0.041
0.173
4.2
4
(
1)
"
0.041
0.089
2.2
3
(
1)
"
0.041
0.067
1.6
2
(
1)
"
0.041
0.044
1.1
4
(
2)
diatom
0.0052
0.173
33.3
4
(
1)
"
0.0052
0.089
17.1
3
(
1)
"
0.0052
0.067
12.9
2
(
1)
"
0.0052
0.044
8.5
The
acute
high
risk
levels
of
concern
for
aquatic
plants
are
exceeded
for
both
vascular
and
nonvascular
plants.
The
exceedences
range
1
­
4
fold
for
vascular
plants
and
8.5
­
33
fold
for
non­
vascular
plants.
Currently,
EFED
does
not
perform
assessments
for
chronic
risk
to
aquatic
plants.
25
Table
7.
Species
Risk
Quotients
on
turf
for
aquatic
plants
based
upon
a
duckweed
(
Lemna
gibba)
NOAEC
of
<
8
ppb.

Rate
of
Application
in
lbs
ai/
A
(
Number
of
Applications).
Species
EC50
(
ppm)
EEC
(
ppm)
Non­
target
plant
RQ
(
EEC/
EC50)

4
(
2)
duckweed
0.008
0.173
21.6
4
(
1)
0.008
0.089
11.1
3
(
1)
0.008
0.067
8.4
2
(
1)
0.008
0.044
5.5
An
analysis
of
the
results
indicate
that
the
plant
acute
high
risk
level
of
concern
is
exceeded
for
vascular
plants
with
exceedences
ranging
5.5
­
22
fold.
26
CHAPTER
7:
TERRESTRIAL
EXPOSURE
AND
RISK
a.
Terrestrial
Hazard
Summary
The
available
toxicity
data
are
listed
in
Appendix
D.
Oxadiazon
appears
to
be
practically
non­
toxic
to
avian
species
on
an
subacute
basis
(
Northern
Bobwhite
quail
and
mallard
duck
LC
50
>
5,000
ppm)
and
slightly
to
practically
non­
toxic
to
birds
on
an
acute
basis
(
Bobwhite
quail
LD
50
>
2,150
mg/
kg;
mallard
LD
50
=
1,040
mg/
kg).
Chronic
testing
showed
no
reproductive
effects
at
500
ppm..
At
greater
than
1,000
ppm
mortality
was
noted
for
adult
females
(
Bobwhite
quail).

Mammalian
toxicity
data
suggest
that
this
compound
is
practically
non­
toxic
to
small
mammals
on
an
acute
basis
(
rat
LD
50
>
5,000
mg/
kg).
Reproductive
effects
were
noted
at
>
200
ppm
that
resulted
in
inactive
mammary
tissue
and
fetal/
neonatal
death.
Acute
toxicity
studies
to
honey
bees
show
that
oxadiazon
was
practically
non­
toxic
(
LD
50
>
25
ug/
bee).

b.
Risk
to
Avian
Species
(
Acute/
Chronic)

Table
8
provides
avian
acute
and
chronic
RQs
from
exposure
to
multiple
applications
of
oxadiazon
EC
to
turf
for
the
maximum
three
application
rates
(
4.0,
3.0
and
2.0
lbs
ai/
A)
and
two
split
applications
(
1.0
lb
ai/
A,
4
times/
6
months;
1.3
lbs
ai/
A,
3
times/
6
months).
The
maximum
three
applications
have
the
potential
for
chronic
exposure
to
birds
that
feed
on
plants
and
grass
(
e.
g.
ducks,
geese)
and
may
result
in
toxic
risk
to
these
birds
(
RQ
=
1.0
­
2.0).
The
split
application
appears
to
lower
this
chronic
exposure
and
risk
(
RQ
=
<
1).
Exposure
from
the
granular
formulation
was
evaluated
(
Appendix
F)
because
birds
may
be
exposed
to
granular
pesticides
through
ingestion
when
foraging
for
food
or
grit.
RQ
values
were
calculated
for
three
weight
classes
of
birds
(
1000g
waterfowl,
180g
upland
game
bird,
and
20g
songbird).
All
scenarios
for
the
granular
resulted
in
no
acute
risk
to
birds
(
RQ
<
1.5
­
2.0).
However,
the
potential
chronic
concern
noted
for
non
endangered
birds
suggest
that
oxadiazon
may
present
a
risk
to
endangered
species
(
RQ
>
0.1)

The
estimated
environmental
concentration
(
EEC)
values
used
for
foliar
terrestrial
exposure
are
derived
from
the
Kenega
nomograph,
as
modified
by
Fletcher
et
al.
(
1994),
based
on
a
large
set
of
actual
field
residue
data.
The
upper
limit
values
from
the
nomograph
represent
the
95th
percentile
of
residue
values
from
actual
field
measurements
(
Hoerger
and
Kenega,
1972).
The
Fletcher
et
al.,
(
1994)
modifications
to
the
Kenega
nomograph
are
based
on
measured
field
residues
from
249
publications,
including
information
on
118
species
of
plants,
121
pesticides,
and
17
chemical
classes.
These
modifications
represent
the
95th
percentile
of
the
expanded
data
set.
Risk
quotients
are
based
on
the
most
sensitive
LC
50
and
NOAEC
for
birds.
EFED
also
used
the
ELL­
FATE
model
for
multiple
applications,
incorporating
the
appropriate
dissipation
half­
life
to
generate
EECs.
Single
application
EECs
reflect
day
zero
maximum
Fletcher
residue
values
(
lbs
ai/
A
x
240;
110;
135;
15
ppm).

Current
EFED
policy
assumes
that
pesticide
dissipation
from
foliar
surfaces
is
primarily
due
to
degradation
or
dissipation
by
one
or
more
processes
including,
photolysis,
hydrolysis,
microbial
27
degradation
and
volatilization.
If
adequate
foliar
dissipation
data
are
not
available
then
a
half­
life
not
to
exceed
35
days
will
be
used
in
the
EEC
calculations.

Table
8.
Avian
acute
and
chronic
risk
quotients
(
RQ's)
as
generated
through
ELL­
FATE
for
broadcast
ground
spray
applications
for
oxadiazon.
RQ's
are
based
on
mallard
duck
LC50
>
5,000
ppm
and
NOAEC
=
500
ppm.
The
EEC
reflects
the
turf
use
with
the
three
highest
use
rate
(
4.0,
3.0
and
2.0
lbs
ai/
A,
2
applications)
and
two
split
applications
(
1.0
lb
ai/
A,
4
times/
6
months;
1.3
lbs
ai/
A,
3
times/
6
months).

Site
Application
Rate
lbs
ai/
A
(#
appl)
Food
Item
Maximum
EECs
(
ppm)
Acute
RQ
(
EEC/
LC50)
Chronic
RQ
(
Max.
EEC/
NOAEC)

Turf
(
EC)
4.0
(
2)
Short
grass
Tall
grass
Broadleaf
plants/
insects
Seeds
984.1
451.1
553.6
61.5
<
0.2
<
0.1
<
0.1
<
0.0
2.0
1.0
0.1
0.1
Turf
(
EC)
3.0
(
2)
Short
grass
Tall
grass
Broadleaf
plants/
insects
Seeds
739.6
339.0
416.0
46.2
<
0.1
0.0
<
0.1
0.0
1.5
1.0
1.0
0.1
Turf
(
EC)
2.0
(
2)
Short
grass
Tall
grass
Broadleaf
plants/
insects
Seeds
493.1
226.0
277.3
30.8
<
0.1
0.0
0.0
0.0
1.0
0.4
0.5
0.1
Turf
(
EC)
1.0
(
split
4
applications/
6
months)
Short
grass
Tall
grass
Broadleaf
plants/
insects
Seeds
424.4
194.5
238.7
26.5
<
0.1
0.0
0.0
0.0
1.0
0.4
0.5
0.1
Turf
(
EC)
1.3
(
split
3
applications/
6
months)
Short
grass
Tall
grass
Broadleaf
plants/
insects
Seeds
257.0
117.8
144.6
16.1
<
0.1
0.0
0.0
0.0
1.0
0.4
0.5
0.1
28
c.
Risk
to
Mammalians
(
Acute,
Chronic)

Our
assessment
(
Table
9
and
10)
suggests
that
the
proposed
use
rates
(
4.0,
3.0
and
2.0
lbs
ai/
A),
as
well
as
the
split
use
rates
(
1.0
and
1.3
lbs
ai/
A)
should
not
result
in
acute
risk
to
mammals
(
RQ
<
0.2).
However,
these
application
scenarios
can
result
in
significant
chronic
exposure
and
risk
to
mammalian
herbivores
and
insectivores
(
15g,
35g,
and
1000g)
with
RQ
values
ranging
from
1.5
­
9.9.
This
chronic
risk
to
non
endangered
mammalian
species
also
suggests
the
potential
for
impact
to
endangered
species.

Estimating
the
potential
for
adverse
effects
to
wild
mammals
is
based
upon
EFED's
draft
1995
SOP
of
mammalian
risk
assessments
and
methods
used
by
Hoerger
and
Kenaga
(
1972)
as
modified
by
Fletcher
et
al.,
(
1994).
The
concentration
of
oxadiazon
in
the
diet
is
expected
to
be
acutely
toxic
to
50%
of
the
test
organisms
is
determined
by
dividing
the
LD
50
value
(
usually
the
rat
LD
50
)
by
the
per
cent
body
weight
consumed.
A
risk
quotient
is
then
determined
by
dividing
the
EEC
by
the
acute
toxicity
value.

RQ
=
EEC
(
ppm)
LD
50
(
mg/
kg)/
%
Body
weight
consumed
RQ
values
are
calculated
for
four
different
kinds
of
food
(
short
grass,
tall
grass,
forage/
insects,
and
seeds)
that
are
expected
to
be
consumed
by
mammalian
herbivores,
insectivores,
and
granivores.
The
per
cent
body
weight
consumed
for
herbivores
and
insectivores
corresponding
to
the
three
weight
categories
(
15,
35,
and
1000
g)
is
assumed
to
be
95%,
66%,
and
15%,
respectively.
Granivores
are
expected
to
have
a
different
per
cent
body
weight
consumption
for
the
same
weight
categories
(
21%,
15%,
and
3%,
respectively).
Chronic
toxicity
values
were
based
on
the
NOAEC
from
a
rat
reproductive
study.
In
order
to
evaluate
chronic
concerns,
a
maximum
EEC
was
generated
through
the
ELL­
FATE
model
that
takes
into
consideration
pesticide
half­
life,
application
rate,
number
of
applications,
and
intervals
between
applications
(
first
order
kinetics
model).
In
order
to
evaluate
possible
toxic
risk
to
terrestrial
organisms,
three
application
rates
(
4.0,
3.0,
and
2.0
lbs
ai/
A,
at
2
applications/
6
months)
and
two
split
applications
(
1.0
lbs
ai/
A
applied
4
times/
6
month
and
1.3
lbs
ai/
A
applied
3
times/
6
month)
were
run.
Our
objective
was
to
find
not
only
the
highest
rate
that
may
cause
toxic
risk,
but
the
lowest
rate
that
might
result
in
lower
risk.
29
Table
9.
Mammalian
acute
risk
quotients
as
generated
through
ELL­
FATE
for
ground
application
of
oxadiazon
(
EC).
RQ's
are
based
on
rat
(
Rattus
norvegicus)
LD50
>
5,000
mg/
kg,.
The
EEC
reflects
the
three
highest
use
rate
(
4.0,
3.0
and
2.0
lbs
ai/
A,
2
applications)
and
two
split
applications
(
1.0
lb
ai/
A,
4
times/
6
months;
1.3
lbs
ai/
A,
3
times/
6
months).

Crop
Application
Rate
lbs
ai/
A
(
#
of
applications)
Body
Wt.
(
g)
%
Body
Wt.
Consumed
Acute
RQ
Short
Grass
Acute
RQ
Forage
and
Small
Insects
Acute
RQ
Large
Insects
Acute
RQ
Seeds
Turf
(
EC)
4.0
(
2)
15
35
1000
95/
21
66/
15
15/
3
<
0.2
<
0.1
0.0
<
0.1
<
0.1
0.0
<
0.1
<
0.1
0.0
0.0
0.0
0.0
Turf
(
EC)
3.0
(
2)
15
35
1000
95/
21
66/
15
15/
3
<
0.1
<
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Turf
(
EC)
2.0
(
2)
15
35
1000
95/
21
66/
15
15/
3
<
0.1
<
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Turf
(
EC)
1.0
(
split
4
applications/
6
months)
15
35
1000
95/
21
66/
15
15/
3
<
0.1
<
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Turf
(
EC)
1.3
(
split
3
applications/
6
months)
15
35
1000
95/
21
66/
15
15/
3
<
0.1
<
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1
Acute
species
concerns
(>
0.1)
2
Acute
restricted
use
(>
0.2)
30
Table
10.
Mammalian
chronic
risk
quotients
as
generated
through
ELL­
FATE
for
ground
application
of
oxadiazon
are
based
on
rat
(
Rattus
norvegicus)
NOAEC
=
100
ppm.
The
EEC
reflects
the
three
highest
use
rate
(
4.0,
3.0
and
2.0
lbs
ai/
A,
2
applications)
and
two
split
applications
(
1.0
lb
ai/
A,
4
times/
6
months;
1.3
lbs
ai/
A,
3
times/
6
months).

Crop
Application
Rate
lbs
ai/
A
(
#
of
applications)
Food
Items
Max.
EEC
(
ppm)
Chronic
RQ
(
Max.
EEC/
NOAEC)

Turf
(
EC)
4.0
(
2)
Short
Grass
Tall
Grass
Broadleaf
plant/
Insects
Seeds
986.1
452.0
554.7
61.6
9.91
4.51
5.51
1.01
Turf
(
EC)
3.0
(
2)
Short
Grass
Tall
Grass
Broadleaf
plant/
Insects
Seeds
739.6
339.0
416.0
46.2
7.41
3.41
4.21
0.5
Turf
(
EC)
2.0
(
2)
Short
Grass
Tall
Grass
Broadleaf
plant/
Insects
Seeds
493.1
226.0
227.3
30.8
4.91
2.31
2.81
0.3
Turf
(
EC)
1.0
(
split
4
applications/
6
months)
Short
Grass
Tall
Grass
Broadleaf
plant/
Insects
Seeds
424.4
194.5
238.7
26.5
3.21
1.51
1.81
0.2
Turf
(
EC)
1.3
(
split
3
applications/
6
months)
Short
Grass
Tall
Grass
Broadleaf
plant/
Insects
Seeds
257.0
117.8
144.6
16.1
4.71
2.21
2.71
0.3
1
Chronic
risk
(
LOC
>
1)

d.
Risk
to
Non­
target
Insects
EFED
does
not
do
risk
assessments
on
insects.
However,
it
appears
that
oxadiazon
exposure
to
honeybees
should
present
low
risk.

e.
Risk
to
Terrestrial
Plants
The
risk
assessment
of
oxadiazon
to
terrestrial
plants
and
aquatic
plants
(
vascular
and
nonvascular)
cannot
be
completed
because
of
an
inadequate
data
base.
It
should
be
noted
that
the
assessment
for
nonvascular
plants
provided
here
is
incomplete
in
that
the
assessment
is
based
on
a
supplemental
study
and
additional
nonvascular
plant
species
testing
is
being
recommended.
31
f.
Endocrine
Disruption
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
the
recommendations
of
its
Endocrine
Disruptor
Screening
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
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).

When
the
appropriate
screening
and
or
testing
protocols
being
considered
under
the
Agency's
Endocrine
Disruptor
Screening
Program
have
been
developed,
oxadiazon,
may
be
subjected
to
additional
screening
and
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.
Issues
that
have
raised
this
concern
include
the
findings
from
fish
reproduction
effects
(
larval
and
embryo
survival,
egg
hatchability)
and
invertebrate
reproduction
effects
(
reduced
neonate
production)
also
suggest
endocrine
disruption.
32
CONCLUSIONS
The
Tier
I
GENEEC
calculated
RQ
values
for
the
use
of
oxadiazon
on
turf
suggests
that
chronic
exposure
of
this
compound
has
the
potential
for
toxic
risk
to
freshwater
and
estuarine/
marine
fish
(
RQ
=
39.3
­
131.8)
and
aquatic
invertebrates
(
RQ
=
3.9
­
36.7).
The
chronic
Level
of
Concern
(
LOC)
was
exceeded
by
up
to
132­
fold
for
fish
and
37­
fold
for
aquatic
invertebrates.
Although
our
initial
risk
assessment
suggests
that
acute
exposure
of
oxadiazon
to
aquatic
systems
should
result
in
relatively
lower
short
term
risk
to
non
endangered
fish
and
aquatic
invertebrates
(
RQ
=
0.1
­
0.5)
there
is
uncertainty
regarding
possible
risk
enhancement
through
phototoxicity.
Since
oxadiazon
is
a
light­
dependent
peroxidizing
herbicide
(
LDPH),
enhanced
toxicity
through
exposure
to
high
levels
of
solar
radiation
is
a
possible
concern
regarding
aquatic
organisms
that
inhabit
small,
shallow
water
bodies.
Oxadiazon
is
also
a
lipophilic,
persistent
compound
that
can
be
absorbed
to
particulate
and
sediment.
This
combination
of
chemical/
physical
attributes
and
the
relatively
high
toxicity
profile
to
fish
and
invertebrates
suggest
concern
for
accumulation
in
the
sediments.
Since
sediments
can
act
as
a
repository
for
lipophilic
compounds,
there
can
be
direct
impact
to
aquatic
organisms
through
respiration,
ingestion,
dermal
contact,
and/
or
indirect
impact
through
alterations
of
the
food
chain.
The
herbicidal
properties
of
this
compound
also
suggest
toxicity
to
aquatic
plants
and
the
resulting
alteration
of
habitats.

Our
terrestrial
risk
assessment
for
the
oxadiazon
EC
use
on
turf
was
conducted
by
using
the
ELLFATE
model.
An
evaluation
of
EECs
generated
for
each
of
the
three
application
rates
(
4.0,
3.0,
and
2.0
lbs
ai/
A)
and
split
applications
(
1.0
and
1.3
lbs
ai/
A)
showed
that
oxadiazon
chronic
exposure
to
mammals
(
RQ
=
1.5
­
9.9)
has
the
potential
for
toxic
risk.
Chronic
risk
to
mammalians
can
be
upto
10
fold
greater
than
the
LOC
with
the
potential
to
impact
herbivores,
granivores
and
insectivores.
Relative
to
mammalian
effects,
chronic
risk
to
avian
species
(
RQ
=
1.0
­
2.0)
appears
lower
but
still
exceeds
EFEDs
LOC
(
RQ
=
1).
This
exposure
may
result
in
impact
to
herbivorous
birds
which
feed
on
grass,
broadleaf
plants,
etc.
Although
acute
exposure
of
this
compound
should
not
present
a
toxic
risk
to
non
endangered
avian
or
mammalian
species
(
RQ
<
0.1),
the
potential
for
chronic
risk
suggests
a
possible
endangered
avian
species
concern.
Exposure
from
the
granular
formulation
was
evaluated
(
Appendix
F)
because
birds
may
be
exposed
to
granular
pesticides
through
ingestion
when
foraging
for
food
or
grit.
RQ
values
were
calculated
for
three
weight
classes
of
birds
(
1000g
waterfowl,
180g
upland
game
bird,
and
20g
songbird).
The
maximum
use
rate
scenarios
for
the
granular
resulted
in
acute
risk
to
small
songbirds
(
RQ
=
1.5
­
2.0).

Since
oxadiazon
is
practically
non­
toxic
to
the
honey
bee,
minimal
risk
to
these
organisms
is
anticipated.
However,
since
oxadiazon
is
a
herbicide,
risk
to
non­
nontarget
aquatic
and
terrestrial
plants
can
be
anticipated.
RQ's
generated
for
Tier
I
testing
of
aquatic
plants
(
vascular
RQ
=
1.1
­
4.2
and
nonvascular
RQ
=
8.5
­
33.3)
show
the
potential
for
toxic
risk
to
aquatic
plants.
Although
there
does
not
appear
to
be
an
acute
risk
to
endangered
birds
and
mammals
there
may
be
chronic
concerns
as
reflected
in
the
two­
fold
LOC
exceedences
for
non
endangered
terrestrial
animals.
Therefore,
our
assessment
suggests
that
endangered
terrestrial
species
(
birds,
mammals,
and
terrestrial
plants)
may
be
at
risk.

Aquatic
studies
that
showed
fish
reproduction
effects
(
larval
and
embryo
survival,
egg
hatchability)
and
invertebrate
reproduction
effects
(
reduced
neonate
production)
suggest
that
oxadiazon
may
be
subject
to
additional
screening
or
testing
to
better
characterize
effects
related
to
possible
endocrine
disruption.
33
APPENDIX
A:
REFERENCES
CITED
Supplemental
and
Core
Ecotoxicity
Studies
Cited
MRID
111806
Posner,
S.;
McGee,
G.;
Freeman,
L.
(
1971)
Acute
Toxicity
(
LD50)
in
Mallard
Ducks:
[
RP­
17623
Technical
Assay
99.1]:
Experimental
Reference
No.
A­
408.
(
Unpublished
study
received
Aug
23,
1972
under
359­
658;
prepared
by
Biometric
Testing,
Inc.,
submitted
by
Rhone­
Poulenc,
Inc.,
Monmouth
Junction,
NJ;
CDL:
003179­
B)

MRID
111807
Posner,
S.;
McGee,
G.;
Freeman,
L.
(
1971)
Acute
Toxicity
(
LD50)
in
Bobwhite
Quail:
[
RP­
17623
Technical
Assay
99.1]:
Experimental
Reference
No.
A­
408.
(
Unpublished
study
received
Aug
23,
1972
under
359­
658;
prepared
by
Biometric
Testing,
Inc.,
submitted
by
Rhone­
Poulenc,
Inc.,
Monmouth
Junction,
NJ;
CDL:
003179­
C)

MRID
112622
Posner,
S.;
McGee,
G.;
Freeman,
L.
(
1971)
Acute
Toxicity
(
LD50)
in
Bobwhite
Quail:
Experimental
Reference
No.
A­
408.
(
Unpublished
study
received
Oct
14,
1972
under
2F1269;
prepared
by
Biometric
Testing,
Inc.,
submitted
by
Rhodia,
Inc.,
New
Brunswick,
NJ;
CDL:
091824­
D)

MRID
41610101
Pedersen,
C.
(
1990)
Oxadiazon
Technical:
21­
Day
Acute
Oral
LD50
Study
in
Bobwhite
Quail:
Lab
Project
Number:
BLAL/
NO/
89
QD
139.
Unpublished
study
prepared
by
Bio­
Life
Associates,
Ltd.
35
p.

MRID
41610102
Pedersen,
C.
(
1990)
Oxadiazon
Technical:
8­
Day
Acute
Dietary
LC50
Study
in
Bobwhite
Quail:
Lab
Project
Number:
BLAL/
NO/
89
QC
141.
Unpublished
study
prepared
by
Bio­
Life
Associates,
Ltd.
82
p.

MRID
41610103
Pedersen,
C.
(
1990)
Oxadiazon
Technical:
8­
Day
Acute
Dietary
LC50
Study
in
Mallard
Ducklings:
Lab
Project
Number:
BLAL/
NO/
89
DC
137.
Unpublished
study
prepared
by
Bio­
Life
Associates,
Ltd.
80
p.

MRID
41610105
Giddings,
J.
(
1990)
Oxadiazon
Technical­
Toxicity
to
the
Marine
Diatom
Skeletonema
costatum:
Lab
Project
Number:
90­
7­
3384:
10566­
1089­
6137­
450.
Unpublished
study
prepared
by
Springborn
Laboratories,
Inc.
55
p.

MRID
41610106
Giddings,
J.
(
1990)
Oxadiazinon
Technical­
Toxicity
to
the
Freshwater
Diatom
Navicula
pelliculosa:
Lab
Project
Number:
90­
8­
3423;
10566­
1089­
6137­
440.
Unpublished
study
prepared
by
Springborn
Laboratories,
Inc.
52
p.

MRID
41610108
Giddings,
J.
(
1990)
Oxadiazon
Technical­
Toxicity
to
the
Freshwater
Green
Alga
Selenastrum
capricornutum:
Amended
Report:
Lab
Project
Number:
90­
8­
3422;
10566.1089.6137.437.
Unpublished
study
prepared
by
Springborn
Laboratories,
Inc.
52
p.
34
MRID
41610107
Giddings,
J.
(
1990)
Oxadiazon
Technical­
Toxicity
to
the
Duckweed
Lemma
gibba
G3:
Final
Report:
Lab
Project
Number:
90­
7­
3389;
10566.1089.6137.410.
Unpublished
study
prepared
by
Springborn
Laboratories,
Inc.
48
p.

MRID
41784301
Blakemore,
G.;
Burgess,
D.
(
1991)
Chronic
Toxicity
of
Oxadiazon
Technical
to
Daphnia
magna
under
Flow­
thru
Conditions:
Final
Reort:
Lab
Project
Number:
38369.
Unpublished
study
prepared
by
Analytical
Bio­
Chemistry
Labs.,
Inc.
349
p.

MRID
41898001
Hoberg,
J.
(
1991)
Oxadiazon
Technical­­
Determination
of
Effects
on
Seed
Germination,
Seedling
Emergence
and
Vegetative
Vigor
of
Ten
Plant
Species:
Final
Report:
Lab
Project
Number:
90­
11­
3547:
10566­
0790­
6165­
610.
Unpublished
study
prepared
by
Springborn
Laboratories,
Inc.
164
p.

MRID
41993201
Fletcher,
D.;
Pedersen,
C.
(
1991)
Oxadiazon
Technical:
Toxicity
and
Reproduction
Study
in
Mallard
Ducks:
Lab
Project
Number:
89
DR
35.
Unpublished
study
prepared
by
Bio­
Life
Associates,
Ltd.
138
p.

MRID
41993202
Fletcher,
D.;
Pedersen,
C.
(
1991)
Oxadiazon
Technical:
Toxicity
and
Reproduction
Study
in
Bobwhite
Quail:
Lab
Project
Number:
89
QR
39.
Unpublished
study
prepared
by
Bio­
Life
Associates,
Ltd.
145
p.

MRID
42330401
Sword,
M.;
Northup,
R.
(
1992)
Acute
Flow­
Through
Toxicity
of
Oxadiazon
to
Rainbow
Trout
(
Oncorhynchus
mykiss):
Lab
Project
Number:
39729.
Unpublished
study
prepared
by
ABC
Laboratories,
Inc.
211
p.

MRID
42331801
Blasberg,
J.;
Bowman,
J.
(
1992)
Acute
Toxicity
of
Oxadiazon
to
Daphnia
magna
under
Flow­
through
Conditions:
Amended
Final
Report:
Lab
Project
Number:
39730.
Unpublished
study
prepared
by
ABC
Labs,
Inc.
254
p.

MRID
42350601
Sword,
M.;
Northup,
R.
(
1992)
Acute
Flow­
through
Toxicity
of
Oxadiazon
to
Bluegill
(
Lepomis
macrochirus):
Final
Report:
Lab
Project
Number:
39728.
Unpublished
study
prepared
by
ABC
Labs.,
Inc.
194
p.

MRID
42468301
Beevers,
M.
(
1992)
Acute
Contact
Toxicity
of
Oxadiazon
Technical
to
Honey
Bees
(
Apis
mellifera
L.):
Lab
Project
Number:
CAR
160­
92.
Unpublished
study
prepared
by
California
Agricultural
Research,
Inc.
14
p.
42570301
Dionne,
E.
(
1992)
Oxadiazon
Technical­­
Acute
Toxicity
to
Eastern
Oyster
(
Crassostrea
virginica)
under
Flow­
through
Conditions:
Final
Report:
Lab
Project
Number:
92­
7­
4329:
10566.0392.6238.504.
Unpublished
study
prepared
by
Springborn
Labs,
Inc.
63
p.

MRID
42615801
Machado,
M.
(
1992)
Oxadiazon
Technical­­
Acute
Toxicity
to
Sheepshead
Minnow
(
Cyprinodon
variegatus)
under
Flow­
through
Conditions:
Final
Report:
Lab
Project
Number:
92­
8­
4383
10566.0392.6237.505.
Unpublished
study
prepared
by
Springborn
Labs,
Inc.
66
p.

MRID
42615802
Machado,
M.
(
1992)
Oxadiazon
Technical­­
Acute
Toxicity
to
Mysid
Shrimp
(
Mysidopsis
35
bahia)
under
Flow­
through
Conditions:
Final
Report:
Lab
Project
Number:
92­
7­
4348:
10566.0392.6236.515.
Unpublished
study
prepared
by
Springborn
Labs,
Inc.
65
p.

MRID
42659001
Mihaich,
E.
(
1993)
Response
to
EPA
Review
of
Oxadiazon
Anabaena
flos­
aquae
Study
(
MRID
41610104)
and
Selenastrum
caprocornutum
(
sic)
Study
(
MRID
41610108):
Lab
Project
No.
NS/
EMM­
93­
03.
Unpublished
study
prepared
by
Rhone­
Poulenc
Ag
Co.
and
Springborn
Labs.,
Inc.
10
p.

MRID
42921601
Rhodes,
J.
(
1993)
Early
Life­
Stage
Toxicity
of
Oxadiazon
Technical
to
the
Fathead
Minnow
(
Pimephales
promelas)
Under
Flow­
Through
Conditions:
Lab
Project
Number:
40024.
Unpublished
study
prepared
by
ABC
Labs.
Inc.,
Environmental
Toxicology.
432
p.

Literature
Citation,
Ecotoxicity
Study
Guardigli,
A,
et.
al.,
"
Residue
Uptake
and
Depletion
Measurements
of
Dietary
Oxadiazon
in
Mammalian
and
Avian
Species."
Archives
of
Environmental
Contamination
and
Toxicology
Vol.
4,
145­
154
(
1976)

Supplemental
and
Core
Environmental
Fate
Studies
Cited
(
MRID#
42226701;
DP
Barcode
D192825)
Armstrong,
K.,
B.
D.
Cameron,
S.
A.
Chapleo,
B.
E.
Hall,
and
A.
Haswell.
1991.
Oxadiazon:
Bioaccumulation
test
in
bluegill
sunfish.
IRI
Project
No.
381195;
Report
No.
8385.
Unpublished
study
performed
by
Inversk
Research
International,
Tranent,
Scotland,
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
Manley,
J.
D.,
I.
A.
J.
Hardy,
and
E.
A.
Savage.
1992.
Herbicides:
Oxadiazon
spectroscopic
investigation
of
metabolites
from
a
[
14C]­
oxadiazon
bioaccumulation
test
in
bluegill
sunfish.
IRI
Project
No.
381195.
Unpublished
study
performed
by
Rhône­
Poulenc
Agriculture
Limited,
Ongar,
United
Kingdom,
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
No
Study
ID)

(
MRID#
41898201;
DP
Barcode
D165559)
Das,
Y.
T.
1991.
Photodegradation
of
[
Phenyl(
U)­
14C]
Oxadiazon
on
Soil
under
Artificial
Sunlight.
Unpublished
study
performed
by
Innovative
Scientific
Services,
Inc.
Piscataway,
N.
J.,
and
sponsored
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
MRID#
41897201;
DP
Barcode
D192825)
Corgier,
M.
M.
C.,
and
A.
P.
Plewa.
1991.
14Coxadiazon
photodegradation
in
aqueous
solution.
Study
No.
90­
29.
Filing
Reference
AG/
CRLD/
AN/
9115609.
Unpublished
study
performed
by
Rhône­
Poulenc
Secteur
Agro,
Lyon,
France,
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
MRID#
41863603;
DP
Barcode
D165559)
Corgier,
M.
M.
C.,
and
Robin,
J.
M.
1991.
14COxadiazon
Hydrolysis
at
25

C.
Unpublished
study
performed
by
Rhône­
Poulenc,
Lyon,
France,
and
submitted
by
Rhône­
Poulenc,
Research
Triangle
Park,
NC
(
MRID#
41898202,
DP
Barcode
D165559)
Dykes,
J.
1991.
Soil
Adsorption/
Desorption
with
14C­
36
Oxadiazon.
An
unpublished
study
performed
by
Analytical
Bio­
Chemistry
Laboratories,
Inc.,
Columbia,
MO,
nad
submitted
by
Rhône
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
MRID#
41767401;
DP
Barcode
D192825)
Norris,
F.
A.
1991.
A
terrestrial
field
soil
dissipation
study
with
oxadiazon.
Study
No.
EC/
P­
89­
0014.
File
No.
40642.
Unpublished
study
performed
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
MRID#
41889501;
DP
Barcode
D165559)
Priestley,
D.
B.,
Lowden,
P.,
and
Savage,
E.
A.
1991.
Oxadiazon­
14C:
Leaching
Study
with
Four
Soils.
Unpublished
study
performed
by
Rhône­
Poulenc
Agriculture
Limited,
Essex,
England,
and
submitted
by
Rhône­
Poulenc
Ag
Company,
Research
Triangle
Park,
NC
(
MRID#
42772801;
DP
Barcode
D192825)
Waring,
A.
R.
1993a.
[
14C]
Oxadiazon:
Aerobic
soil
metabolism.
HUK
Study
No.
68/
111;
Report
No.
7218.
Unpublished
study
performed
by
Hazleton
UK,
Harrogate,
North
Yorkshire,
England,
and
submitted
by
Rhône­
Poulenc
Agriculture
Company,
Research
Triangle
Park,
NC
(
MRID#
42773802;
DP
Barcode
D192825)
Waring,
A.
R.
1993b.
[
14C]
Oxadiazon:
Anaerobic
aquatic
metabolism.
HUK
Study
No.
68/
112;
Report
No.
7214.
Unpublished
study
performed
by
Hazleton
UK,
Harrogate,
North
Yorkshire,
England,
and
submitted
by
Rhône­
Poulenc
Agriculture
Company,
Research
Triangle
Park,
NC
Supplemental
HED
Study,
for
Environmental
Fate
Use
MRID#
44995501
Howell,
C.,
and
Wedekind,
W.
1999.
"
Oxadiazon:
Determination
of
Transferable
Turf
Residues
on
Turf
Treated
with
CHIPCO
®
G."
An
unpublishded
study
sponsored
by
Rhône
Poulenc
Corporation,
NC,
and
performed
by
ABC
Laboratories,
Inc.,
MO,
Test
Guideline
875.2100,
ABC
Study
Number
44951.

MRID#
44995502
Howell,
C.
1999.
"
Oxadiazon:
Determination
of
Transferable
Turf
Residues
on
Turf
Treated
with
CHIPCO
®
RONSTAR
®
50WSP."
An
unpublishded
study
sponsored
by
Rhône
Poulenc
Ag
Company,
NC,
and
performed
by
ABC
Laboratories,
Inc.,
MO,
Test
Guideline
875.2100,
ABC
Study
Number
44952.
37
APPENDIX
B:
FATE
SUMMARIES
161­
1
Hydrolysis
(
MRID#
41863603;
Core)

[
14C]­
Oxadiazon
(
phenyl
ring­
labeled),
at
0.48
mg/
L,
was
stable
in
pH
4,
5,
and
7
sterile
aqueous
buffered
solutions
incubated
in
the
dark
at
25

C
for
31
days.

At
pH
9,
oxadiazon
was
hydrolyzed
with
a
calculated
half­
life
of
38
days.
Oxadiazon
averaged
93.64%
of
the
applied
at
5
days,
and
49.98%
at
31
days.
The
main
degradate
found
was
!
1­
trimethyl
acetyl­
2­(
2,4­
dichloro­
5­
isopropoxyphenyl)
hydrazine
(
RP26123),
which
increased
to
45%
of
the
applied
at
31
days.

All
other
metabolites
were
present
at
<
10%
of
the
applied.

161­
2
Photodegradation
in
Water
(
MRID#
41897201;
Core)

[
14C]
oxadiazon
(
phenyl
ring­
labeled),
at
0.5
mg/
L,
photodegraded
with
a
half­
life
of
21.2
hours
(
or
the
equivalent
of
2.75
days
of
summer
sunlight
in
Florida)
in
pH
5
buffered
solutions
that
were
continuously
irradiated
with
a
xenon
arc
lamp
at
25
+
1

C
for
up
to
42
hours.
Oxadiazon
declined
from
an
average
of
98.68%
of
the
recovered
immediately
posttreatment,
to
42.46%
at
26
hours.
In
the
dark
controls,
no
degradation
was
observed
for
42
hours.

The
degradates
identified
were
RP36939
and
RP37084,
present
at
up
to
4.8%
and
11.5%
of
the
applied
radioactivity,
respectively.
Up
to
20
degradates
were
isolated,
present
at
<
8%
of
the
applied
radioactivity.
The
registrant
did
not
provide
the
chemical
names
for
RP36939
and
RP37084.
The
later
one
was
a
maximum
of
11.5%
of
the
applied
at
42
hours
(
last
test
interval),
when
the
level
of
oxadiazon
had
decreased
to
<
28%
of
the
applied.
It
is
not
likely
that
RP37084
would
be
formed
in
significantly
higher
quantities.

161­
3
Photolysis
on
Soil
(
MRID#
41898201;
Core)

[
14C]
oxadiazon
(
phenyl
ring­
labeled),
at
9.4­
11.3
ppm,
degraded
slowly
with
a
calculated
half­
life
of
165
days
on
a
sandy
loam
soil
irradiated
with
xenon
arc
lamp
intermitently
at
25

C.
There
was
no
significant
breakdown
of
the
parent
under
non­
irradiated
conditions.
In
the
irradiated
samples,
oxadiazon
averaged
90.2%
of
the
applied
at
day
0
posttreatment,
and
averaged
86.6%
at
day
30.
In
the
dark
samples,
oxadiazon
averaged
90.2%
of
the
applied
at
day
0,
and
90.8%
at
day
30.
The
following
minor
degradates
were
observed
in
small
quantities.

!
2­
tertiobutyl­
4­(
2,4­
dichloro­
5­
hydroxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP25496),
and
!
3­(
2,4­
dichloro­
5­
methoxyphenyl)­
5­
tertiobutyl­
1,3,4­

4­
oxadiazolin­
2­
one
(
RP17272).
38
161­
4
Photodegradation
in
Air
(
Waived)
163­
2
Laboratory
Volatility
(
Waived)
163­
3
Field
Volatility
(
Waived)

All
three
data
requirements
were
waived,
based
on
the
relatively
low
vapor
pressure
(
1.0x10­
6
mm
Hg)
and
Henry's
Law
Constant
(
calc.
4.51x10­
7
Atm
·
m3/
mol)
of
oxadiazon.
EFED
believes
that
this
value
is
relatively
low
and
that
volatility
of
oxadiazon
may
not
be
an
important
route
of
dissipation
for
oxadiazon.
This
conclusion
is
further
confirmed
by
the
results
of
the
Aerobic
Soil
Metabolism
study
(
MRID#
42772801),
which
shows
only
a
small
fraction
of
the
applied
was
volatilized
after
1
year
(
see
below).

162­
1
Aerobic
Soil
Metabolism
(
MRID#
42772801;
Core)

[
14C]­
Oxadiazon
(
uniformly
ring
labeled)
degraded
slowly
in
sandy
loam
soil
that
was
incubated
aerobically
in
the
dark
at
about
25

C
and
approximately
75%
of
soil
water
capacity
at
0.33
bar
for
1
year.
The
registrant­
calculated
initial
half­
life
was
well
beyond
the
experimental
time
frame
(
t
½
=
841
days).
Oxadiazon
comprised
98.87­
92.33%
of
the
applied
immediately
posttreatment
and
decreased
slowly
to
72.11­
76.47%
of
the
applied
after
365
days.
Unextracted
[
14C]
residues,
and
volatilized
[
14C]
residues
comprised
4.82%
and
2.95%
of
the
applied
at
365
days,
respectively.

Five
degradates
were
identified:

!
3­(
2,4­
dichloro­
5­
methoxyphenyl)­
5­
tertiobutyl­
1,3,4­

4­
oxadiazolin­
2­
one
(
RP17272)

!
2­(
carboxy­
2­
propyl)­
4­(
2,4­
dichloro­
5­
hydroxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP26471)

!
2­
tertiobutyl­
4­(
2,4­
dichloro­
5­
hydroxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP25496)

!
2­(
2­
carboxy­
2­
propyl)­
4­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP26449)
and
!
1­
trimethylacetyl­
2­(
2,4­
dichloro­
5­
isopropoxyphenyl)
hydrazine
(
RP26123).

These
degradates
were
present
at
concentrations

1.51%
of
the
applied
throughout
the
study.
Three
other
areas
of
radioactivity
were
isolated,
but
not
identified,
at

1%
of
the
applied.

162­
3
Anaerobic
Aquatic
Metabolism
(
MRID#
42773802:
Supplemental)

[
14C]
Oxadiazon
(
uniformly
ring
labeled)
degraded
slowly
with
an
observed
half­
life
of
approximately
1
year
in
anaerobic
(
flooded
plus
nitrogen
atmosphere)
sandy
loam
soil
that
was
incubated
in
the
dark
at
about
25

C
for
1
year;
oxadiazon
comprised
91.7­
91.8%
of
the
applied
immediately
posttreatment
and
decreased
to
47.3­
47.9%
of
the
applied
at
366
days.
At
366
days,
unextracted
[
14C]
residues
were
2.47%
of
the
applied
and
[
14C]
volatiles
totaled
0.02%
of
the
applied.

Five
degradates
were
identified:

!
2­(
carboxy­
2­
propyl)­
4­(
2,4­
dichloro­
5­
hydroxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP26471)

!
2­
tertiobutyl­
4­(
2,4­
dichloro­
5­
hydroxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP25496)

!
2­(
2­
carboxy­
2­
propyl)­
4­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP26449)
39
!
2,4­
dichloroisopropoxybenzene
(
RP36227)
and
!
1­
trimethylacetyl­
2­(
2,4­
dichloro­
5­
isopropoxyphenyl)
hydrazine
(
RP26123).

All
the
degradates
were
present
at
concentrations

3.76%
of
the
applied
througout
the
experiments.
In
addition,
one
"
cluster"
of
[
14C]
residues
was
isolated
from
the
floodwater
at
a
maximum
of
18.2%
of
the
applied,
and
one
was
isolated
from
the
soil
at
a
maximum
of
20.8%
of
the
applied
at
181
day.
These
[
14C]
residues
were
not
further
characterized.

163­
1
Mobility
in
Soil
(
MRID#
41889601;
Core)

[
14C]­
Oxadiazon
(
phenyl
ring
labeled),
at
4
ppm
showed
a
low
mobility
in
soil
leaching
columns
containing
sand,
loam,
and
two
sandy
loam
soils.
The
material
was
either
freshly
applied
(
parent
pesticide),
or
applied
after
30
days
of
aerobic
incubation.

A
similar
profile
was
observed
in
the
aged
and
unaged
soil
columns.
The
majority
of
the
radioactivity
(

80.5%)
remained
in
the
upper
0­
6
inches
of
the
36
inches
long
columns,
indicating
a
low
mobility
for
parent
oxadiazon
in
these
soil.
The
amount
of
radiaoctivity
recovered
from
the
leachate
was
small
(

0.2%).
Solvent
extracts
were
shown
to
contain
only
parent
compound.
The
total
recoveries
of
radioactivity
were
92.6­
102.4%.

163­
1
Mobility
­
Leaching
and
Adsorption/
Desorption
(
MRID#
41898202;
Supplemental)

Based
on
batch
equilibrium
studies,
at
nominal
concentrations
of
0.1­
0.3
ppm
and
25

C,
[
14C]
Oxadiazon
demonstrated
slight
mobility
in
sand
and
sandy
loam,
and
low
mobility
in
a
clay
and
silt
loam.
The
Kd
and
Koc
constants
obtained
from
the
Freundlich
isotherms
were
as
follows:

Table
1.
Mobility
of
Oxadiazon
adsorption.
desorption
Soil
type
%
OC
Kd
Koc
Kd
Koc
silt
loam
1.2
16.91
1409
21.35
1779
clay
1.2
22.83
1903
51.72
4310
sandy
loam
0.4
11.39
2848
41.00
10250
sand
0.25
8.17
3268
10.34
 
4136
The
soil
treatment
included
grinding
in
a
grist
mill.
It
is
not
known
what
is
the
particle
size
distribution.
The
particle
size
of
the
soil
is
a
determinant
of
its
adsortivity.
A
cursory
revision
of
the
DER
for
this
study
indicates
that
1/
n
values
were
not
reported
for
any
soil
type.
40
164­
1
Terrestrial
Field
Dissipation
(
MRID#
41767401;
Core)

Oxadiazon
slowly
dissipated
from
two
field
plots
located
in
San
Juan
Bautista,
California
(
sandy
loam
soil)
and
Clayton,
North
Carolina
(
loamy
sand)
and
planted
with
Junipers
and
Azaleas,
respectively.
The
plots
were
treated
with
oxadiazon
at
4.48
kg
ai/
ha
(
4.06
lb
ai/
A).
The
registrant­
calculated
initial
half­
life
of
oxadiazon
in
the
California
site
was
65
days,
and
40
days
in
the
North
Carolina
site.
The
dissipation
rate
was
near
zero
during
the
winter
season
in
both
locations.
Oxadiazon
appears
to
persist
over
time.
In
the
0­
to
15­
cm
soil
depth
of
the
California
site,
oxadiazon
was
1.80­
3.60
ppm
immediately
posttreatment
and
decreased
to
0.08­
0.18
ppm
at
12­
16
months.
In
the
North
Carolina
site
oxadiazon
was
1.08­
2.05
ppm
immediately
posttreatment
and
decreased
to
0.02­
0.43
ppm
at
12­
16
months.
In
the
15­
to
30­
cm
soil
depth
of
both
plots,
oxadiazon
was

0.12
ppm
through
2
months
and

0.01
ppm
thereafter.

Generally,
oxadiazon
residues
were
detected
only
in
the
upper
30
cm
of
the
soil,
with
occasional
small
detections
in
the
15­
to
30­
cm
soil
depth.
The
degradates
!
3­(
2,4­
Dichloro­
5­
methoxyphenyl)­
5­
tertiobutyl­
1,3,4­

4­
oxadiazolin­
2­
one
(
RP­
17272)
and
!
2­(
2­
Carboxy­
2­
propyl)­
4­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
5­
oxo­
1,3,4­
oxadiazolin
(
RP­
26449)

were
each
present
at
<
0.02
ppm
in
the
0­
to
15­
cm
soil
depth,
and
were
not
detected
in
the
deeper
soil
layers.
Total
irrigation
plus
rainfall
during
the
study
period
was
14.03
cm
in
the
California
site,
and
20.03
cm
in
the
North
Carolina
site.

165­
4
Bioaccumulation
in
Fish
(
MRID#
42226701;
Core)

Oxadiazon
residues
accumulated
in
bluegill
sunfish
continuously
exposed
to
8.8
ug/
L
of
oxadiazon,
with
average
bioconcentration
factors
of
368x
for
the
edible
tissues
(
muscle),
2239x
for
the
nonedible
tissues
(
viscera),
and
1111x
for
the
whole
fish.
Maximum
mean
[
14C]
residue
concentrations
were
4.26
ug/
g
for
the
edible
tissues,
26.83
ug/
g
for
the
nonedible
tissues,
and
11.94
ug/
g
for
whole
fish.
Steady
state
concentrations
were
observed
within
3
days
of
exposure.
Depuration
was
rapid,
with
an
observed
half­
life
of
about
1
day;
by
day
3
of
the
depuration
period,
83%
of
the
accumulated
[
14C]
residues
had
been
eliminated
from
whole
fish,
and
by
day
14,
>
97%
were
eliminated.

Parent
[
14C]
oxadiazon
was
detected
only
once
in
the
fish
inedible
tissues
on
day
14;
three
degradates
were
identified
in
the
fish
samples:

!
5­(
1­
hydroxymethyl­
1­
methylethyl)­
3­(
2,4­
dichloro­
5­
isopropoxyphenyl)­
1,3,4­
oxadiazol­
2(
3H)­
one
(
M8),
which
was
15.8­
24.6%
of
the
[
14C]
residues
extracted
from
the
edible
fish;

!
An
ether
glucuronide
conjugate
of
M8
(
chemical
name
not
provided),
which
was
25.8­
31.6%
of
the
[
14C]
residues
extracted
from
the
edible
fish;
and
!
5­(
1­
hydroxymethyl­
1­
methylethyl)­
3­(
2,4­
dichloro­
5­
hydroxyphenyl)­
1,3,4­
oxadiazol­
2(
3H)­
one
(
M10),
which
was
8.5­
13.4%
of
the
[
14C]
residues
extracted
from
the
edible
fish.
41
875.2100
Transferable
Oxadiazon
Residues
on
Turf
Treated
with
the
Product
in
the
Granular
Formulation
(
MRID#
44995501;
supplemental)

EFED
had
available
a
review
by
Versar,
Inc.,
a
contractor
for
HED
studies.
This
study
and
the
review
were
prepared
as
a
requirement
of
the
Health
Effects
Division.
Only
some
highlights
of
the
study
are
mentioned
here
for
information
only,
since
EFED
investigated
the
usefulness
of
the
study
for
modeling
purposes.

This
test
was
performed
with
the
granular
formulation
of
oxadiazon.
Samples
were
taken
with
cotton
cloth
sheets,
which
were
exposed
to
a
large
turf
area.
These
samples
were
taken
at
various
test
intervals,
starting
from
prior
to
application,
from
three
geographical
locations.
It
appears
that
the
registrant
did
not
intend
to
compare
the
actual
amount
of
oxadiazon
residues
present
on
and
in
turf,
compared
to
the
amount
present
in
the
cotton
cloth.
The
registrant
may
have
developed
that
information,
but
it
was
not
available
to
EFED
at
this
time.

The
reported
LOQ
was
25
µ
g/
sample,
while
the
LOD
was
not
provided.
Several
results
were
less
than
the
LOQ.

The
authors
intended
also
to
report
the
degradates
RP25496+
RP17272
(
together),
and
RP26449.
These
degradates,
however,
were
not
detected
in
any
sampling
interval
through
the
study.

Half­
life
of
the
transferable
residues
may
be
around
2­
7
days
for
the
granular
formulation.
By
no
means
that
would
definitely
mean
that
7
days
would
be
representative
of
the
half­
life
of
oxadiazon
in
the
turf
because
there
is
no
evidence
that
the
methodology
used
was
in
some
way
quantitatively
measuring
the
total
levels
of
oxadiazon
in
the
foliage.
For
the
purpose
of
running
EFED
models,
this
study
can
only
be
regarded
at
best
as
supplemental.

875.2100
Transferable
Oxadiazon
Residues
on
Turf
Treated
with
the
Product
in
the
Liquid
Formulation
(
MRID#
44995502;
supplemental)

EFED
had
available
a
review
by
Versar,
Inc.,
a
contractor
for
HED
studies.
This
study
and
the
review
were
prepared
as
a
requirement
of
the
Health
Effects
Division.
Only
some
highlights
of
the
study
are
mentioned
here
for
information
only,
since
EFED
investigated
the
usefulness
of
the
study
for
modeling
purposes.

The
product
was
formulated
in
Wettable
Soluble
Packets
(
of
powder
containing
oxadiazon
at
about
2%
of
a.
i.).
The
product
was
applied
at
3
lb
a.
i./
A.
Samples
were
taken
in
triplicate
with
cotton
cloth
sheets,
which
were
exposed
to
a
large
turf
area.
These
samples
were
taken
at
various
test
intervals,
starting
from
prior
to
application,
from
two
geographical
locations.
Sampling
occurred
between
March
26
and
April
8,
1999.
It
appears
that
the
registrant
did
not
intend
to
compare
the
actual
amount
of
oxadiazon
residues
present
on
turf
and
in
turf,
compared
to
the
amount
present
in
the
cotton
cloth.
The
registrant
may
have
developed
that
information,
but
it
was
not
available
to
EFED
at
this
time.
42
The
reported
LOQ
was
25
µ
g/
sample,
while
the
LOD
was
not
provided.
Several
results
were
less
than
the
LOQ.
In
addition,
the
authors
intended
also
to
report
the
degradates
RP25496+
RP17272
(
together),
and
RP26449.
It
appears,
however,
that
these
degradates
were
not
detected
in
any
sampling
interval
through
the
study.

In
the
California
site,
the
data
was
very
variable,
and
it
was
judged
unreliable
by
the
authors
of
the
study.
The
review
does
not
offer
the
author's
detailed
rationale
with
respect
to
this
invalidation.
On
the
other
hand,
a
study
conducted
in
Georgia,
yielded
most
samples
at
>
LOQ,
although
the
range
of
the
actual
results
was
several
orders
of
magnitude
larger
than
range
of
the
fortified
samples.
Based
on
the
results
of
the
27
samples
available,
the
half­
life
was
about
2.3
days,
with
a
correlation
coefficient
(
R2)
of
0.7.
By
no
means
that
would
definitely
mean
that
2
days
would
be
representative
of
the
half­
life
of
oxadiazon
in
the
turf
because
there
is
no
evidence
that
the
methodology
used
was
in
some
way
quantitatively
measuring
the
total
levels
of
oxadiazon
in
the
foliage.
Furthermore,
out
of
two
studies
conducted
with
the
liquid
formulation,
only
one
produced
results
with
acceptable
concentrations
above
the
LOQ.
EFED
believes
that
for
the
purpose
of
running
EFED
models,
this
study
can
only
be
regarded
at
best
as
informative,
and,
for
the
safety
of
the
public,
the
default
value
of
35
days
should
be
used.
43
APPENDIX
C:
ECOLOGICAL
TOXICITY
DATA
Toxicity
testing
reported
in
this
section
is
not
representative
of
the
wide
diversity
of
terrestrial
and
aquatic
organisms
in
the
United
States.
Two
surrogate
bird
species,
the
bobwhite
quail
and
the
mallard
duck,
are
used
for
the
680
plus
species
of
birds
found
in
this
country.
For
mammals,
acute
studies
are
usually
limited
to
the
Norway
rat
or
the
house
mouse.
Reptiles
are
not
tested,
as
these
are
assumed
to
be
subject
to
similar
toxicological
effects
as
birds.
Of
approximately
100,000
species
of
insects,
spiders,
and
other
terrestrial
arthropods,
toxicity
tests
are
usually
required
only
for
the
honey
bee.
Only
two
surrogate
fish
species
(
rainbow
trout
and
bluegill
sunfish)
are
used
to
represent
the
over
2,000
species
of
freshwater
fish
found
in
this
country.
Amphibians
are
not
tested,
as
these
are
assumed
to
be
subject
to
similar
toxicological
effects
as
fish.
One
crustacean,
the
water
flea,
is
used
to
represent
all
freshwater
invertebrates.
Estuarine/
marine
animal
acute
toxicity
testing
is
usually
limited
to
a
crustacean,
a
mollusk,
and
a
fish.
Testing
on
aquatic
plants
is
limited
to
one
species
of
vascular
plant
(
duckweed)
and
four
species
of
algae
and
diatoms.

Toxicity
to
Terrestrial
Organisms
Birds,
Acute,
Subacute
and
Chronic
An
acute
oral
toxicity
study
using
the
technical
grade
of
the
active
ingredient
(
TGAI)
is
required
to
establish
the
toxicity
of
oxadiazon
to
birds.
The
avian
oral
LD
50
is
an
acute,
single­
dose
laboratory
study
designed
to
estimate
the
quantity
of
toxicant
required
to
cause
50%
mortality
in
a
test
population
of
birds.
The
preferred
test
species
is
either
the
Mallard
Duck,
a
waterfowl,
or
Bobwhite
quail,
an
upland
gamebird.
The
TGAI
is
administered
by
oral
intubation
to
adult
birds,
and
the
results
are
expressed
as
LD
50
milligrams
(
mg)
active
ingredient
(
a.
i.)
per
kilogram
(
kg).
Toxicity
category
descriptions
are
as
follows:

If
the
LD50
is
less
than
10
mg
a.
i./
kg,
then
the
test
substance
is
very
highly
toxic.
If
the
LD50
is
10­
to­
50
mg
a.
i./
kg,
then
the
test
substance
is
highly
toxic.
If
the
LD50
is
51­
to­
500
mg
a.
i./
kg,
then
the
test
substance
is
moderately
toxic.
If
the
LD50
is
501­
to­
2,000
mg
a.
i./
kg,
then
the
test
substance
is
slightly
toxic.
If
the
LD50
is
greater
than
2,000
mg
a.
i./
kg,
then
the
test
substance
is
practically
nontoxic.
44
Study
results
are
in
the
table
below.

Table
C.
1.
Avian
Acute
Oral
Toxicity
Species
%
ai
LD50
(
mg/
kg)
Toxicity
Category
MRID/
Lab/
Year
Classification
Northern
Bobwhite
(
Colinus
virginianus)
99.1
6000
practically
nontoxic
111807
(
also
under
112622)
Biometric
Testing,
Inc.
1971
Supplemental1
Mallard
(
Anas
platyrhynchos)
99.1
1040
slightly
toxic
111806
Biometric
Testing,
Inc.
1971
Supplemental1
Northern
bobwhite
(
Colinus
virginianus)
97.49
>
2150
(
no
bird
mortality)
practically
nontoxic
41610101
Bio­
Life
Associates,
Ltd
1990
Core
1
studies
are
scientifically
sound;
although
deemed
satisfactory
for
registration
of
oxadiazon
in
the
early
1970'
s,
EFED
required
a
new
study
in
1991under
Phase
IV
Reregistration.

Based
on
results
of
the
above
studies,
oxadiazon
may
be
categorized
slightly
to
practically
nontoxic
to
birds
on
an
acute
oral
basis.
The
guideline
71­
1(
a
)
is
fulfilled
(
MRID
41610101).

Two
dietary
studies
using
the
TGAI
are
required
to
establish
the
toxicity
of
oxadiazon
to
birds.
These
avian
dietary
LC
50
tests,
using
the
Mallard
Duck
and
Bobwhite
Quail,
are
acute,
eight­
day
dietary
laboratory
studies
designed
to
estimate
the
quantities
of
toxicant
required
to
cause
50%
mortality
in
the
two
respective
test
populations
of
birds.
The
TGAI
is
administered
by
mixture
to
juvenile
birds'
diets
for
five
days
followed
by
three
days
of
"
clean"
diet,
and
the
results
are
expressed
as
LC
50
parts
per
million
(
ppm)
active
ingredient
(
a.
i.)
in
the
diet.
Toxicity
category
descriptions
are
as
follows:

If
the
LC50
is
less
than
50
ppm
a.
i.,
then
the
test
substance
is
very
highly
toxic.
If
the
LC50
is
50­
to­
500
ppm
a.
i.,
then
the
test
substance
is
highly
toxic.
If
the
LC50
is
501­
to­
1,000
ppm
a.
i.,
then
the
test
substance
is
moderately
toxic.
If
the
LC50
is
1001­
to­
5,000
ppm
a.
i.,
then
the
test
substance
is
slightly
toxic.
If
the
LC50
is
greater
than
5,000
ppm
a.
i.,
then
the
test
substance
is
practically
nontoxic.

Study
results
are
tabulated
below.

Table
C.
2.
Avian
Subacute
Dietary
Toxicity
Species
%
ai
LC50
(
ppm)
Toxicity
Category
MRID/
Lab/
Year
Study
Classification
Bobwhite
Quail
(
Colinus
virginianus)
97.49
>
5,000
(
no
bird
mortality)
practically
nontoxic
41610102
Bio­
Life
Associates,
Ltd
1990
Core
Mallard
Duck
(
Anas
platyrhynchos)
97.49
>
5000
(
no
bird
mortality)
practically
nontoxic
41610103
Bio­
Life
Associates,
Ltd
1990
Core
45
Based
on
results
of
the
above
studies,
oxadiazon
may
be
characterized
practically
nontoxic
to
birds
on
a
subacute
basis.
The
guideline
71­
2(
a)
for
bobwhite
(
MRID
41610102)
and
71­
2(
b)
for
mallard
duck
(
MRID
41610103)
are
fulfilled.

Avian
reproduction
tests
are
designed
to
estimate
the
quantity
of
toxicant
required
to
adversely
affect
the
reproductive
capabilities
of
a
test
population
of
birds.
The
TGAI
is
administered
by
mixture
to
breeding
birds'
diets
throughout
their
breeding
cycle.
Test
birds
are
approaching
their
first
breeding
season
and,
generally,
are
18­
to­
23
weeks
old.
The
onset
of
the
exposure
period
is
at
least
10
weeks
prior
to
egg
laying.
Exposure
period
during
egg
laying
is
generally
10
weeks
with
a
withdrawal
period
of
three
additional
weeks
if
reduced
egg
laying
is
noted.
Results
are
expressed
as
No
Observed
Adverse
Effect
Concentration
(
NOAEC)
and
various
observable
effect
levels,
such
as
the
Lowest
Observable
Adverse
Effect
Concentration
(
LOAEC),
quantified
in
units
of
parts
per
million
of
active
ingredient
(
ppm)
in
the
diet.
Study
results
are
tabulated
below
.

Table
C.
3.
Avian
Chronic
Toxicity
Species/
Study
Duration
%
ai
NOAEC/
LOAEC
(
ppm)
LOAEC
Endpoints
MRID/
Lab/
Year
Classification
Mallard
Duck
(
Anas
platyrhynchos)
20
weeks
97.49
>
1000
(
highest
dose
tested)/
LOAEC
not
determined
not
determined
41993201
Bio­
Life
Associates,
Ltd
1991
Supplemental1
Northern
Bobwhite
(
Colinus
virginianus)
21
weeks
97.49
500/
1000
mortality
among
adult
females
41993202
Bio­
Life
Associates,
Ltd
1991
Core
1
study
was
classified
supplemental
because
a
NOAEC
was
not
established.

Based
on
the
results
of
the
Bobwhite
reproduction
study,
the
ingestion
of
oxadiazon
at
levels
up
to
1,000
ppm,
the
highest
dose
concentration
tested,
had
no
effect
on
any
reproductive
parameter
or
viability
of
F
1
the
offspring
(
reproductive
NOAEC
>
1000
ppm).
However,
mortality
among
females
at
that
level
was
quite
high
(
33%).
The
study
authors
stated
that
due
to
the
inconsistency
and
lack
of
dose­
related
pathology
observations
in
birds
found
dead
or
sacrificed
at
study
termination,
the
pathology
observations
were
attrbuted
to
factors
other
than
the
test
substance.
EFED,
in
the
absence
of
information
on
the
cause
of
the
deaths,
considered
the
mortality
attributable
to
treatment.
The
chronic
NOAEC
was
set
at
500
ppm.
The
guideline
71­
4(
a)
is
fulfilled
(
MRID
41993202).

The
avian
reproduction
study
using
mallard
resulted
in
a
NOAEC
greater
than
1000
ppm,
the
highest
dose
tested.
This
study
was
classified
supplemental
because
a
NOAEC
was
not
established.
Although
the
study
is
classified
supplemental,
it
does
not
have
to
be
repeated
because
(
1)
the
Bobwhite
was
more
sensitive
in
testing,
and
(
2)
the
highest
dose
tested
is
greater
than
the
highest
estimated
environmental
concentration
for
the
highest
application
rate
(
turf;
4
lb
ai/
A;
maximum
Fletcher
value
240
x
4
=
960
ppm).
The
guidelines
71­
4(
a)
for
the
Bobwhite
(
MRID
41993202)
and
71­
4(
b)
for
the
mallard
(
MRID
41993201)
are
considered
fulfilled.
46
Mammals,
Acute
and
Chronic
Wild
mammal
testing
is
required
on
a
case­
by­
case
basis,
depending
on
the
results
of
lower
tier
laboratory
mammalian
studies,
intended
use
pattern
and
pertinent
environmental
fate
characteristics.
In
most
cases,
rat
or
mouse
toxicity
values
obtained
from
the
Agency's
Health
Effects
Division
(
HED)
substitute
for
wild
mammal
testing.
The
acute
toxicity
values
below
were
taken
from
HED's
Tox
One­
Liners.
Chronic
toxicity
information
was
obtained
from
the
Health
Effects
Division
Hazard
Identification
Assessment
Review
Committee
(
HIARC
report
HED
DOC.
NO.
014469;
February
8,
2001).

Table
C.
4.
Mammalian
Acute
Toxicity
Species
%
ai
Test
Type
LD50
(
mg/
kg)
Toxicity
Category)
MRID
laboratory
rat
(
Rattus
norvegicus)
97.5
oral
­
single
dose
>
5,000
(
combined
sexes)
practically
nontoxic
41866501
Table
C.
5.
Mammalian
Chronic
Toxicity
Species
%
ai
Test
Type
NOAEC/
LOAEC
(
ppm)
Affected
Endpoints
MRID
laboratory
rat
(
Rattus
norvegicus)
96.6
Three
generation
reproduction
study
(
feeding)
100/
200
Fewer
and
lighter
pups
at
birth
With
a
rat
LD50
>
5,000
mg
/
kg,
oxadiazon
may
be
characterized
practically
nontoxic
to
mammals
on
an
acute
oral
basis.
The
rat
reproduction
study
showed
a
NOAEC/
LOAEC
of
100/
200
ppm.
Chronic
effects
included
fewer
and
lighter
pups
at
birth.

Insect
Acute
Contact
A
honey
bee
acute
contact
study
using
the
TGAI
is
required
to
support
outdoor
uses.
The
acute
contact
LD
50,
using
the
honey
bee,
Apis
mellifera,
is
an
acute
contact,
single­
dose
laboratory
study
designed
to
estimate
the
quantity
of
toxicant
required
to
cause
50%
mortality
in
a
test
population
of
bees.
The
TGAI
is
administered
by
one
of
two
methods:
whole
body
exposure
to
technical
pesticide
in
a
nontoxic
dust
diluent;
or,
topical
exposure
to
technical
pesticide
via
micro­
applicator.
The
median
lethal
dose
(
LD
50)
is
expressed
in
micrograms
of
active
ingredient
per
bee
(
ug
a.
i./
bee).
Toxicity
category
descriptions
are
as
follows:

If
the
LD50
is
less
than
2
µ
g
a.
i./
bee,
then
the
test
substance
is
highly
toxic.
If
the
LD50
is
2
to
less
than
11
µ
g
a.
i./
bee,
then
the
test
substance
is
moderately
toxic.
If
the
LD50
is
11
µ
g
a.
i./
bee
or
greater,
then
the
test
substance
is
practically
nontoxic
47
Study
results
are
tabulated
below.

Table
C.
6.
Nontarget
Insect
Acute
Contact
Toxicity
Species
%
ai
LD50
(

g/
bee)
Toxicity
Category
MRID/
Lab/
Year
Study
Classification
Honey
bee
(
Apis
mellifera)
95.9
>
25
practically
nontoxic
42468301
California
Agricultural
Research
Inc.
1992
Core
The
LD
50
for
oxadiazon
is
greater
than
25
ug
per
bee,
characterizing
oxadiazon
practically
nontoxic
to
bees.
The
guideline
(
141­
1)
is
fulfilled
(
MRID
42468301).

Insect
Residual
Contact
Honey
bee
toxicity
of
residues
on
foliage
study
is
required
on
an
end­
use
product
for
any
pesticide
intended
for
outdoor
application
when
the
proposed
use
pattern
indicates
that
honey
bees
may
be
exposed
to
the
pesticide
and
when
the
formulation
contains
one
or
more
active
ingredients
having
an
acute
contact
honey
bee
LD
50
which
falls
in
the
moderately
toxic
or
highly
toxic
range.
Since
oxadiazon
is
practically
nontoxic
to
honey
bees
a
honey
bee
toxicity
of
residues
on
foliage
(
Guideline
141­
2)
is
not
required.

Terrestrial
Plant
Testing
The
data
were
deemed
inadequate
for
determining
the
EC
25/
NOAEC
values
of
the
most
sensitive
species
(
Reference:
D166982;
1995
memo
to
SRRD
requesting
repeat
of
all
ten
species
due
to
very
poor
study
with
numerous
deficiencies
and
guideline
deviations).
To
date,
the
studies
have
not
been
submitted
to
EFED.

Aquatic
Organism
Toxicity
Toxicity
to
Freshwater
Organisms
Freshwater
Fish,
Acute
Two
freshwater
fish
toxicity
studies
using
the
TGAI
are
required
to
establish
the
toxicity
of
oxadiazon
to
fish.
The
preferred
test
species
are
rainbow
trout
(
a
coldwater
fish)
and
bluegill
sunfish
(
a
warmwater
fish).
Toxicity
category
descriptions
are
as
follows:
If
the
LC50
is
less
than
0.1
ppm
a.
i.,
then
the
test
substance
is
very
highly
toxic.
If
the
LC50
is
0.1­
to­
1.0
ppm
a.
i.,
then
the
test
substance
is
highly
toxic.
If
the
LC50
is
greater
than
1
and
up
through
10
ppm
a.
i.,
then
the
test
substance
is
moderately
toxic.
If
the
LC50
is
greater
than
10
and
up
through
100
ppm
a.
i.,
then
the
test
substance
is
slightly
toxic.
If
the
LC50
is
greater
than
100
ppm
a.
i.,
then
the
test
substance
is
practically
nontoxic.
48
Study
results
are
tabulated
below.

Table
C.
7.
Freshwater
Fish
96­
hr
Acute
Toxicity
Species/
Flow­
through
or
Static
%
ai
LC50
(
ppm)
Toxicity
Category
MRID
/
Lab/
Year
Study
Classification
Bluegill
sunfish
(
Lepomis
macrochirus)
/
static
97.4
0.88
(
nominal)
highly
toxic
McCann
/
1977
Supplemental1
Bluegill
sunfish
(
Lepomis
macrochirus
/
flow­
through
95.9
1.2
(
measured)
moderately
toxic
42350601
ABC
Labs.,
Inc.
1992
Core
Rainbow
Trout
(
Oncorhynchus
mykiss)/
static
97.4
1.05
(
nominal)
moderately
toxic
McCann
/
1977
Supplemental1
Rainbow
Trout
(
Oncorhynchus
mykiss)
/
flow­
through
95.9
1.2
(
measured)
moderately
toxic
42330401
ABC
Labs,
Inc.
1992
Core
1
EFED
considers
McCann
studies
as
scientifically
sound
and
useful
for
risk
assessment
purposes,
even
though
studies
do
not
follow
current
protocols
and
raw
data
are
not
available
for
verification
of
results.

Based
on
the
above
studies,
oxadiazon
may
be
characterized
moderately
to
highly
toxic
to
freshwater
warmwater
fish
on
an
acute
basis.
The
guideline
72­
1(
a)
for
bluegill
is
fulfilled
(
MRID
42350601
and
McCann
study).
Oxadiazon
may
be
characterized
as
moderately
toxic
to
freshwater
coldwater
fish
on
an
acute
basis.
The
guideline
72­
1(
c)
for
rainbow
trout
is
fulfilled
(
MRID
42350401
and
McCann
study).

Freshwater
Fish,
Chronic
A
freshwater
fish
early
life­
stage
test
using
the
TGAI
is
required
for
oxadiazon
because
the
end­
use
product
may
be
transported
to
water
from
the
intended
use
site,
and
an
acute
aquatic
toxicity
value
is
less
than
1
ppm.
Acceptable
freshwater
test
species
are
rainbow
trout,
brook
trout,
coho
salmon,
chinook,
bluegill,
brown
trout,
lake
trout,
northern
pike,
fathead
minnow,
white
sucker
and
channel
catfish.
The
fish
early
life­
stage
is
a
laboratory
test
designed
to
estimate
the
quantity
of
toxicant
required
to
adversely
effect
the
reproductive
capabilities
of
a
test
population
of
fish.
The
TGAI
is
administered
into
water
containing
the
test
species,
providing
exposure
throughout
a
critical
life­
stage,
and
the
results
are
expressed
as
a
No
Observed
Adverse
Effect
Concentration
(
NOAEC)
and
LOAEC
(
Lowest
Observed
Adverse
Effect
Concentration).
Testing
results
are
summarized
below.
49
Table
C.
8.
Freshwater
Fish
Chronic
Toxicity
Species/
Static
or
Flow­
through
Study
Duration
%
ai
NOAEC/
LOAEC
(
ppb)/
(
measured/
nominal)
Endpoints
Affected
MRID/
Lab/
Year
Study
Classification
Rainbow
trout
(
Oncorhynchus
mykiss)
>
98%
Radiopurity
0.88/
1.7
(
measured)
egg
hatch
ability
41811601
Analytical
Biochemistry
Labs,
Inc.
1991
Supplemental1
Fathead
minnow
(
Pimephales
promelas)
/
flowthrough
48
days
>
98.5
Radiopurity
33
/
84
(
measured)
growth
(
length
of
fry)
42921601
Analytical
Biochemistry
Labs,
Inc.
1993
Core
1
individual
growth
data
were
not
included
in
report
and
were
requested
so
statistics
could
not
be
verified.

The
rainbow
trout
was
found
to
be
more
sensitive
than
the
fathead
minnow
in
fish
early
life
stage
testing.
The
study
results
of
the
rainbow
trout
study
could
not
be
verified,
because
individual
growth
data
were
not
included
in
the
report.
Although
this
information
was
requested
(
Reference:
D165510;
1/
13/
97
asking
for
raw
data,
and
also
informing
the
registrant
that
the
study
was
acceptable
for
use
in
a
risk
assessment),
the
information
has
not
been
submitted.
The
guideline
72­
4(
a)
for
early
life­
stage
fish
testing
is
fulfilled.

Freshwater
Invertebrates,
Acute
A
freshwater
aquatic
invertebrate
toxicity
test
using
the
TGAI
is
required
to
establish
the
toxicity
of
oxadiazon
to
aquatic
invertebrates.
The
preferred
test
organism
is
Daphnia
magna,
but
early
instar
amphipods,
stoneflies,
mayflies,
or
midges
may
also
be
used
Study
results
are
tabulated
below.

Table
C.
9.
Freshwater
Invertebrate
Acute
Toxicity
(
48­
hour)

Species/
Static
or
Flowthrough
%
ai
EC50
(
ppm)/
(
nominal/
measured)
Toxicity
Category
MRID/
Lab/
Year
Study
Classification
Daphnid
(
Daphnia
magna)/
static
97.4
2.18
(
nominal)
moderately
toxic
McCann
/
1977
Supplemental1
Daphnid
(
Daphnia
magna)
/
flow­
through
95.9
>
2.4
(
measured)
moderately
toxic
42331801
Analytical
biochemistry
Labs.,
Inc.
1992
Core
1
EFED
considers
McCann
studies
as
scientifically
sound
and
useful
for
risk
assessment
purposes.

Based
on
results
of
the
above
studies,
oxadiazon
may
be
categorized
moderately
toxic
to
freshwater
aquatic
invertebrates
on
an
acute
basis.
The
guideline
72­
2(
a)
is
fulfilled
(
MRID
42331801
and
McCann
study).
50
Freshwater
Invertebrate,
Chronic
A
freshwater
aquatic
invertebrate
life­
cycle
test
using
the
TGAI
is
required
because
the
end­
use
product
is
expected
to
be
transported
to
water
from
the
intended
use
site,
and
an
aquatic
acute
LC
50
is
less
than
1.0
ppm.
The
preferred
test
species
is
Daphnia
magna.

Table
C.
10.
Freshwater
Invertebrate
Chronic
Species/
Static
or
Flowthrough
Duration
%
ai
NOAEC/
LOAEC
ppb
(
nominal/
measured)
Endpoints
Affected
MRID/
Lab/
Year
Study
Classification
Daphnid
(
Daphnia
magna)/
flow­
through/
21­
day
97.49
30
/
55
(
measured)
survival;
adult
mean
length;
mean
time
in
days
to
first
brood
and
young/
adult/
reproduction
day
41784301
Analytical
Biochemistry
Labs.,
1991
Core
Based
on
the
results
of
a
21­
day
daphnid
chronic
test
survival
with
effects
on
adult
growth,
time
in
days
to
first
brood
and
number
of
young/
adult/
reproduction
day
at
a
LOAEL
of
55
ppb
,
the
NOAEC
is
30
ppb.
The
guideline
72­
4(
b)
for
invertebrate
life­
cycle
testing
is
fulfilled
(
MRID
41784301).

Toxicity
to
Estuarine
and
Marine
Organisms
Estuarine
and
Marine
Fish,
Acute
Acute
toxicity
testing
with
estuarine
and
marine
fish
using
the
TGAI
is
required
for
oxadiazon
because
the
end­
use
product
may
reach
the
marine/
estuarine
environment.
The
preferred
test
organism
is
the
sheepshead
minnow.
Study
results
are
tabulated
below.

Table
C.
11.
Estuarine/
Marine
Fish
Acute
Toxicity
Species/
static
or
flowthrough
%
a.
i.
LC50)
ppm/
(
measured/
nominal)
Toxicity
Category
MRID/
Lab/
Year
Classification
Sheepshead
minnow/
(
Cyprinodon
variegatus)/
flowthrough
95.9
1.5
(
measured)
moderately
toxic
42615801
Springborn
Labs,
Inc.
1992
Core
Based
on
results
of
the
above
study,
oxadiazon
may
be
categorized
moderately
toxic
to
estuarine
fish
on
an
acute
basis.
The
guideline
72­
3(
a)
is
fulfilled
(
MRID
42615801).

Estuarine
and
Marine
Fish,
Chronic
No
data
are
available.
51
Estuarine
and
Marine
Invertebrates,
Acute
Acute
toxicity
testing
with
estuarine/
marine
invertebrates
using
the
TGAI
is
required
for
oxadiazon
because
the
end­
use
product
may
reach
the
marine/
estuarine
environment.
The
preferred
test
species
are
mysid
shrimp
and
eastern
oyster.
Study
results
are
tabulated
below.

Table
C.
12
.
Estuarine/
Marine
Invertebrate
Acute
Toxicity
Species/
Static
or
Flow­
through
%
a.
i.
96­
hour
EC50
(
ppm)/
(
measured/
nominal)
Toxicity
Category
MRID/
Lab/
Year
Study
Classification
Eastern
oyster
(
Crassostrea
virginica)/
flowthrough
(
shell
deposition)
95.9
0.7
(
measured)
highly
toxic
42570301
Springborn
1992
Supplemental1
Mysid
(
Americamysis
bahia)/
flowthrough
95.9
0.27
(
measured)
highly
toxic
42615802
Springborn
1992
Core
1
classified
supplemental
because
average
growth
in
controls
was
less
than
2
mm.

Based
on
the
results
of
the
above
studies,
oxadiazon
is
considered
to
be
highly
toxic
to
estuarine
invertebrates
on
an
acute
basis.

Although
the
oyster
study
is
classified
supplemental,
the
study
does
not
need
to
be
repeated,
since
the
mysid
was
the
more
sensitive
of
the
two
species,
and
will
be
used
for
risk
assessment
purposes
(
Reference:
D182582;
3/
16/
95).
The
guideline
72­
3(
b)
for
the
oyster
is
considered
fulfilled
(
MRID.
42570301).
The
guideline
72­
3(
c)
for
the
mysid
is
fulfilled
(
MRID
42615802).

Estuarine
and
Marine
Invertebrate,
Chronic
No
data
are
available.
The
guideline
72­
4(
b)
for
the
estuarine/
marine
invertebrate
life
cycle
is
not
fulfilled.

Aquatic
Plants
Tier
I
or
Tier
II
aquatic
plant
growth
testing
using
the
TEP
is
required
for
fungicides.
The
recommendation
is
for
five
species:
freshwater
green
alga
(
Selenastrum
capricornutum),
duckweed
(
Lemna
gibba),
marine
diatom
(
Skeletonema
costatum),
blue­
green
algae
(
Anabaena
flos­
aquae),
and
a
freshwater
diatom.
Results
of
testing
with
the
TGAI
are
below.
52
Table
C.
13.
Nontarget
Aquatic
Plant
Toxicity
(
Tier
II)

Species/
duration
%
A.
I.
EC50/
NOAEC
(
ppb)
MRID
No.
Author/
year
Classification1
duckweed
(
Lemna
gibba)/
14
day
97.49
41
/
<
8
(
measured)
41610107
Springborn
Laboratories
Inc.
1990
Supplemental1
freshwater
green
algae
(
Selenastrum
capricornutum)
/
120
hrs.
97.49
8
/
5.6
(
measured)
41610108
Springborn
Laboratories
Inc.
1990
Core
marine
diatom
(
Skeletonema
costatum)/
120
hrs.
97.49
5.2
/
1.4
(
measured)
41610105
Springborn
Laboratories
Inc.
1990
Core
freshwaterr
diatom
(
Navicula
pelliculosa)/
120
hrs.
97.49
126
/
27
(
measured)
41610106
Springborn
Laboratories
Inc.
1990
Core
1
the
study
was
classified
supplemental
primarily
because
the
exposure
concentrations
used
in
the
test
were
too
high
to
establish
a
NOAEC.
2
study
deemed
invalid
because
EC50
not
established;
registrant
was
asked
to
repeat
study
(
Reference:
D188355;
4/
7/
95).

With
an
EC50
of
5.2
ppb,
the
marine
diatom
appears
to
be
the
most
sensitive
non­
vascular
aquatic
plant
species
tested.

Guideline
123­
2
(
Tier
II)
is
fulfilled
for
four
of
the
five
species
required
(
MRIDs
41610195
through
41610108).
Although
the
duckweed
study
was
classified
supplemental,
it
does
not
have
to
be
repeated
since
adequate
information
was
provided
for
risk
assessment
purposes
(
Reference:
D182582;
3/
16/
95).
A
data
gap
exists
for
freshwater
blue­
green
algae
(
Anabaena
flos­
aquae).
53
APPENDIX
D:
TERRESTRIAL
MODEL
RUNS
ELL­
Fate
Version
1.2
July
19,
2001
Developed
by
Laurence
Libelo.
February,
1999
This
spreadsheet
based
model
calculates
the
decay
of
a
chemical
applied
to
foliar
surfaces
for
single
or
multiple
applications.
It
uses
the
same
principle
as
the
batch
code
models
FATE
and
TERREEC
for
calculating
terrestrial
estimates
exposure
(
TEEC)
concentrations
on
plant
surfaces
following
application.

A
first
order
decay
assumption
is
used
to
determine
the
concentration
at
each
day
after
initial
application
based
on
the
concentration
resulting
from
the
initial
and
additional
applications.
The
decay
is
calculated
by
from
the
first
order
rate
equation:

CT
=
Cie­
kT
or
in
integrated
form:

ln
(
CT/
Ci)
=
kT
Where
CT
=
concentration
at
time
T
=
day
zero.
Ci
=
concentration,
in
parts
per
million
(
PPM)
present
initially
(
on
day
zero)
on
the
surfaces.

Ci
is
calculated
based
on
Kenaga
and
Fletcher
by
multiplying
the
Ci
is
calculated
based
on
the
Kanaga
nomogram
(
Hoerger
and
Kenaga,
(
1972)
as
modified
Fletcher
(
1994).
For
maximum
concentration
the
application
rate,
in
pounds
active
ingredient
per
acre,
is
multiplied
by
240
for
Short
Grass,
110
for
Tall
Grass,
and
135
for
Broad
leafed
plants/
insects
and
15
for
Seeds.
Additional
applications
are
converted
from
pounds
active
ingredient
per
acre
to
PPM
on
the
plant
surface
and
the
additional
mass
added
to
the
mass
of
the
chemical
still
present
on
the
surfaces
on
the
day
of
application.

k
=
degradation
rate
constant
determined
from
studies
of
hydrolysis,
photolysis,
microbial
degradation
etc.
Since
degradation
rate
is
generally
reported
in
terms
of
half­
life
the
rate
constant
is
calculated
from
the
input
half­
life
(
k
=
ln
2/
T1/
2)
instead
of
being
input
directly.
Choosing
which
processes
controls
the
degradation
rate
and
which
half­
life
to
use
in
terrestrial
exposure
calculations
is
open
for
debate
and
should
be
done
by
a
qualified
scientist.

T
=
time,
in
days,
since
the
start
of
the
simulation.
The
initial
application
is
on
day
0.
The
simulation
is
hardwired
to
run
for
365
days.

The
program
calculates
concentration
on
each
type
of
surface
on
a
daily
interval
for
one
year.
54
The
maximum
concentration
during
the
year
and
the
average
concentration
during
the
first
56
days
are
calculated.

The
inputs
used
to
calculate
the
amount
of
the
chemical
present
are
in
highlighted
in
yellow
on
the
spread
sheet.
Outputs
are
in
blue.
The
inputs
required
are:

Application
Rate:
The
maximum
label
application
rate
(
in
pounds
ai/
acre)
Half­
life:
The
degradation
half­
life
for
the
dominate
process(
in
days)
Frequency
of
Application:
The
interval
between
repeated
applications,
from
the
label
(
in
days)
Maximum
#
Application
per
year:
From
the
label
The
calculated
concentrations
are
used
to
calculate
Avian
and
Mammalian
RQ
values.
The
maximum
calculated
concentration
is
divided
by
user
input
values
of
Chronic
No
Observable
Adverse
Effects
Level
and
acute
LC50
to
give
RQs
for
each
plant
type.

The
rat
LC
50
is
calculated
by
dividing
the
mammalian
LD
50
by
0.05
(
to
correct
for
actual
food
consumption)

For
15g,
35g
and
1000
g
mammals
the
RQ
values
are
calculated
by
dividing
the
maximum
concentration
for
each
surface
by
the
LD
50
or
NOAEL
corrected
for
consumption
(
0.95,
0.66
and
.15
body
wt.
for
herbivores
and
insectivores
and
0.21,
0.15
and
0.3
body
wt.
for
granivore)

The
number
of
days
that
the
input
value
of
Chronic
No
Observable
Adverse
Effects
Level
and
acute
LC50
are
exceeded
in
the
first
56
days
is
calculated
by
comparing
the
input
value
to
the
calculated
concentration.

A
graph
of
concentration
on
each
plant
surface
vs
time
is
plotted
and
a
"
level
of
concern"
line
can
be
added
at
a
user
specified
level.

The
maximum
single
application
which
can
be
applied
and
not
exceed
the
toxicity
input
values
if
calculated
by
dividing
the
input
value
by
the
Kenaga
maximum
concentration
for
Short
Grass
(
240).
55
Oxadiazon
Chemical
Name:
turf
Use
EC
Formulation
Inputs
lbs
a.
i./
acre
4
Application
Rate
days
35
Half­
life
days
182
Frequency
of
Application
2
Maximum
#
Apps./
Year
Outputs
56
day
Average
Maximum
Concentration
Concentration
(
PPM)
(
PPM)
585.83
986.12
Short
Grass
#
days
268.51
451.97
Tall
Grass
Exceeded
329.53
554.69
Broadleaf
plants/
Insects
on
short
grass
36.61
61.63
Seeds
(
in
first
56)
0
5000
Acute
LC
50
(
ppm)
Avian
Max
Single
Application
33
500
Chronic
NOAEC
(
ppm)
which
does
NOT
exceed
20.833
Avian
Acute
Chronic
RQ
Acute
RQ
(
lb
a.
i.)
2.083
Avian
Chronic
(
Max.
res.
mult.
apps.)
1.97
0.20
Short
Grass
138.89
Mammalian
Acute
#
days
0.90
0.09
Tall
Grass
0.42
Mammalian
Chronic
Exceeded
1.11
0.11
Broadleaf
plants/
Insects
on
short
grass
0.12
0.01
Seeds
(
in
first
56)
100000
Rat
Calculated
LC
50
(
ppm)
0
5000
Acute
LD
50
(
mg/
kg)
Mammalian
56
100
Chronic
NOAEL
(
mg/
kg)

1000
g
mammal
35
g
mammal
15
g
mammal
Rat
Chronic
Rat
Acute
Dietary
Dietary
Acute
RQ
Acute
RQ
Acute
RQ
RQ
RQ
(
mult.
apps)
(
mult.
apps)
(
mult.
apps)
9.86
0.01
0.03
0.13
0.19
Short
Grass
4.52
0.00
0.01
0.06
0.09
Broadleaf
plants/
insects
5.55
0.01
0.02
0.07
0.11
Large
Insects
0.62
0.00
0.00
0.00
0.00
Seeds
(
granivore)
56
Oxadiazon
Chemical
Name:
turf
Use
EC
Formulation
Inputs
lbs
a.
i./
acre
3
Application
Rate
days
35
Half­
life
days
182
Application
Interval
2
Maximum
#
Apps./
Year
Outputs
56
Day
Average
Maximum
Concentration
Concentration
(
PPM)
(
PPM)
439.37
739.59
Short
Grass
#
days
201.38
338.98
Tall
Grass
Exceeded
247.15
416.02
Broadleaf
plants/
Insects
on
short
grass
27.46
46.22
Seeds
(
in
first
56)
0
5000
Acute
LC50
(
ppm)
Avian
Max
Single
Application
19
500
Chronic
NOAEC
(
ppm)

which
does
NOT
exceed
20.833
Avain
Acute
Chronic
RQ
Acute
RQ
(
lb
a.
i.)
2.083
Avian
Chronic
(
Max.
res.
mult.
apps.)

1.48
0.15
Short
Grass
138.89
Mammalian
Acute
#
days
0.68
0.07
Tall
Grass
2.78
Mammalian
Chronic
Exceeded
0.83
0.08
Broadleaf
plants/
Insects
on
short
grass
0.09
0.01
Seeds
(
in
first
56)

100000
Rat
Calculated
LC
50
(
ppm)
0
5000
Acute
LD50
(
mg/
kg)
Mammalian
56
100
Chronic
NOAEL
(
mg/
kg)

1000
g
mammal
35
g
mammal
15
g
mammal
Rat
Chronic
Rat
Acute
Chronic
RQ
Chronic
RQ
Chronic
RQ
Dietary
Dietary
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
RQ
RQ
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
7.40
0.01
1.11
0.02
4.88
0.10
7.03
0.14
Short
Grass
3.39
0.00
0.51
0.01
2.24
0.04
3.22
0.06
Tall
Grass
4.16
0.00
0.62
0.01
2.75
0.05
3.95
0.08
Broadleaf
plants/
Insects
0.46
0.00
0.07
0.00
0.31
0.01
0.44
0.01
Seeds
57
Oxadiazon
Chemical
Name:
turf
Use
EC
Formulation
Inputs
lbs
a.
i./
acre
2
Application
Rate
days
35
Half­
life
days
182
Application
Interval
2
Maximum
#
Apps./
Year
Outputs
56
Day
Average
Maximum
Concentration
Concentration
(
PPM)
(
PPM)
292.92
493.06
Short
Grass
#
days
134.25
225.99
Tall
Grass
Exceeded
164.77
277.35
Broadleaf
plants/
Insects
on
short
grass
18.31
30.82
Seeds
(
in
first
56)
0
5000
Acute
LC50
(
ppm)
Avian
Max
Single
Application
0
500
Chronic
NOAEC
(
ppm)

which
does
NOT
exceed
20.833
Avain
Acute
Chronic
RQ
Acute
RQ
(
lb
a.
i.)
2.083
Avian
Chronic
(
Max.
res.
mult.
apps.)

0.99
0.10
Short
Grass
138.89
Mammalian
Acute
#
days
0.45
0.05
Tall
Grass
2.78
Mammalian
Chronic
Exceeded
0.55
0.06
Broadleaf
plants/
Insects
on
short
grass
0.06
0.01
Seeds
(
in
first
56)

100000
Rat
Calculated
LC
50
(
ppm)
0
5000
Acute
LD50
(
mg/
kg)
Mammalian
56
100
Chronic
NOAEL
(
mg/
kg)

1000
g
mammal
35
g
mammal
15
g
mammal
Rat
Chronic
Rat
Acute
Chronic
RQ
Chronic
RQ
Chronic
RQ
Dietary
Dietary
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
RQ
RQ
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
4.93
0.00
0.74
0.01
3.25
0.07
4.68
0.09
Short
Grass
2.26
0.00
0.34
0.01
1.49
0.03
2.15
0.04
Tall
Grass
2.77
0.00
0.42
0.01
1.83
0.04
2.63
0.05
Broadleaf
plants/
Insects
0.31
0.00
0.05
0.00
0.20
0.00
0.29
0.01
Seeds
units
=
weeks
not
days
58
Oxadiazon
Chemical
Name:
turf
Use
EC
Formulation
Inputs
lbs
a.
i./
acre
1.33
Application
Rate
days
5
Half­
life
days
8
Application
Interval
6
Maximum
#
Apps./
Year
Outputs
56
Day
Average
Maximum
Concentration
Concentration
(
PPM)
(
PPM)
257.05
475.72
Short
Grass
#
days
117.82
218.04
Tall
Grass
Exceeded
144.59
267.59
Broadleaf
plants/
Insects
on
short
grass
16.07
29.73
Seeds
(
in
first
56)
0
5000
Acute
LC
50
(
ppm)
Avian
Max
Single
Application
0
500
Chronic
NOAEC
(
ppm)

which
does
NOT
exceed
20.833
Avain
Acute
Chronic
RQ
Acute
RQ
(
lb
a.
i.)
2.083
Avian
Chronic
(
Max.
res.
mult.
apps.)

0.95
0.10
Short
Grass
138.89
Mammalian
Acute
#
days
0.44
0.04
Tall
Grass
2.78
Mammalian
Chronic
Exceeded
0.54
0.05
Broadleaf
plants/
Insects
on
short
grass
0.06
0.01
Seeds
(
in
first
56)

100000
Rat
Calculated
LC
50
(
ppm)
0
5000
Acute
LD
50
(
mg/
kg)
Mammalian
52
100
Chronic
NOAEL
(
mg/
kg)

1000
g
mammal
35
g
mammal
15
g
mammal
Rat
Chronic
Rat
Acute
Chronic
RQ
Chronic
RQ
Chronic
RQ
Dietary
Dietary
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
RQ
RQ
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
4.76
0.00
0.71
0.01
3.14
0.06
4.52
0.09
Short
Grass
2.18
0.00
0.33
0.01
1.44
0.03
2.07
0.04
Tall
Grass
2.68
0.00
0.40
0.01
1.77
0.04
2.54
0.05
Broadleaf
plants/
Insects
0.30
0.00
0.04
0.00
0.20
0.00
0.28
0.01
Seeds
units
=
weeks
not
days
59
Oxadiazon
Chemical
Name:
turf
Use
EC
Formulation
Inputs
lbs
a.
i./
acre
1
Application
Rate
days
5
Half­
life
days
8
Application
Interval
8
Maximum
#
Apps./
Year
Outputs
56
Day
Average
Maximum
Concentration
Concentration
(
PPM)
(
PPM)
66.16
358.09
Short
Grass
#
days
30.32
164.13
Tall
Grass
Exceeded
37.21
201.43
Broadleaf
plants/
Insects
on
short
grass
4.13
19.95
Seeds
(
in
first
56)
0
5000
Acute
LC50
(
ppm)
Avian
Max
Single
Application
0
500
Chronic
NOAEC
(
ppm)

which
does
NOT
exceed
20.833
Avain
Acute
Chronic
RQ
Acute
RQ
(
lb
a.
i.)
2.083
Avian
Chronic
(
Max.
res.
mult.
apps.)

0.64
0.06
Short
Grass
138.89
Mammalian
Acute
#
days
0.29
0.03
Tall
Grass
2.78
Mammalian
Chronic
Exceeded
0.36
0.04
Broadleaf
plants/
Insects
on
short
grass
0.04
0.00
Seeds
(
in
first
56)

100000
Rat
Calculated
LC
50
(
ppm)
0
5000
Acute
LD50
(
mg/
kg)
Mammalian
16
100
Chronic
NOAEL
(
mg/
kg)

1000
g
mammal
35
g
mammal
15
g
mammal
Rat
Chronic
Rat
Acute
Chronic
RQ
Chronic
RQ
Chronic
RQ
Dietary
Dietary
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
(
Max.
res.
)
Acute
RQ
RQ
RQ
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
mult.
apps.)
(
mult.
apps)
3.19
0.00
0.48
0.01
2.11
0.04
3.03
0.06
Short
Grass
1.46
0.00
0.22
0.00
0.97
0.02
1.39
0.03
Tall
Grass
1.80
0.00
0.27
0.01
1.18
0.02
1.71
0.03
Broadleaf
plants/
Insects
0.20
0.00
0.03
0.00
0.13
0.00
0.19
0.00
Seeds
60
APPENDIX
E:
DRINKING
WATER
CONCENTRATIONS
The
Tier
I
Estimated
Environmental
Concentrations
were
calculated
using
the
computer
models
FIRST
(
surface
waters)
and
SCIGROW
(
ground
waters).
A
copy
from
the
electronic
document
generated
by
EFED
appears
next.
Drinking
Water
Memo:

U.
S.
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
DC
20460
.
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
May
8,
2001
DPBarcode:
D273599
PC
Code
109001
MEMORANDUM
SUBJECT:
Tier
I
Estimated
Environmental
Concentrations
of
Oxadiazon
FROM:
José
Luis
Meléndez,
Chemist
Environmental
Risk
Branch
V
Environmental
Fate
and
Effects
Division
(
7507C)

THROUGH:
Mah
T.
Shamim,
Ph.
D.,
Chief
Environmental
Risk
Branch
V
Environmental
Fate
and
Effects
Division
(
7507C)

TO:
Margaret
Rice,
Acting
Branch
Chief
Veronique
LaCapra,
CRM
and
Tom
Myers,
Team
Leader
Special
Review
and
Reregistration
Division
(
7508C)

This
memo
presents
the
Tier
I
Estimated
Environmental
Concentrations
(
EECs)
for
oxadiazon,
calculated
using
FIRST
(
surface
water)
and
SCIGROW
(
ground
water)
for
use
in
the
human
health
risk
assessment.
For
surface
water,
the
acute
(
peak)
value
is
246
ppb
and
the
annual
average
value
is
100
ppb.
The
groundwater
screening
concentration
is
0.6
ppb.
These
values
generally
represent
upper­
bound
estimates
of
the
concentrations
that
might
be
found
in
surface
water
and
groundwater
due
to
the
use
of
oxadiazon
on
turf,
which
is
the
major
use
of
the
chemical.

Background
Information
on
FIRST:

FIRST
is
a
new
screening
model
designed
to
estimate
the
pesticide
concentrations
found
in
water
for
use
in
61
drinking
water
assessments.
It
provides
high­
end
values
on
the
concentrations
that
might
be
found
in
a
small
drinking
water
reservoir
due
to
the
use
of
pesticide.
Like
GENEEC,
the
model
previously
used
for
Tier
I
screening
level,
FIRST
is
a
single­
event
model
(
one
run­
off
event),
but
can
account
for
spray
drift
from
multiple
applications.
FIRST
takes
into
consideration
the
so
called
Index
Drinking
Water
Reservoir
by
representing
a
larger
field
and
pond
than
the
standard
GENEEC
scenario.
The
FIRST
scenario
includes
a
427
acres
field
immediately
adjacent
to
a
13
acres
reservoir,
9
feet
deep,
with
continuous
flow
(
two
turnovers
per
year).
The
pond
receives
a
spray
drift
event
from
each
application
plus
one
runoff
event.
The
runoff
event
moves
a
maximum
of
8%
of
the
applied
pesticide
into
the
pond.
This
amount
can
be
reduced
due
to
degradation
on
field
and
the
effect
of
binding
to
soil.
Spray
drift
is
equal
to
6.4%
of
the
applied
concentration
from
the
ground
spray
application
and
16%
for
aerial
applications.

FIRST
also
makes
adjustments
for
the
percent
crop
area.
While
FIRST
assumes
that
the
entire
watershed
would
not
be
treated,
the
use
of
a
PCA
is
still
a
screen
because
it
represents
the
highest
percentage
of
crop
cover
of
any
large
watershed
in
the
US,
and
it
assumes
that
the
entire
crop
is
being
treated.
Various
other
conservative
assumptions
of
FIRST
include
the
use
of
a
small
drinking
water
reservoir
surrounded
by
a
runoffprone
watershed,
the
use
of
the
maximum
use
rate,
no
buffer
zone,
and
a
single
large
rainfall
Background
Information
on
SCIGROW:

SCIGROW
provides
a
groundwater
screening
exposure
value
to
be
used
in
determining
the
potential
risk
to
human
health
from
drinking
water
contaminated
with
the
pesticide.
Since
the
SCIGROW
concentrations
are
likely
to
be
approached
in
only
a
very
small
percentage
of
drinking
water
sources,
i.
e.,
highly
vulnerable
aquifers,
it
is
not
appropriate
to
use
SCIGROW
for
national
or
regional
exposure
estimates.

SCIGROW
estimates
likely
groundwater
concentrations
if
the
pesticide
is
used
at
the
maximum
allowable
rate
in
areas
where
groundwater
is
exceptionally
vulnerable
to
contamination.
In
most
cases,
a
large
majority
of
the
use
area
will
have
groundwater
that
is
less
vulnerable
to
contamination
than
the
areas
used
to
derive
the
SCIGROW
estimate.

Modeling
Inputs
and
Results:

Tables
1
and
2
summarize
the
input
values
used
in
the
model
runs
for
FIRST
1.0
and
SCIGROW,
respectively.
The
lowest
non­
sand
K
D
was
used
in
FIRST
1.0.
The
median
K
OC
value
was
used
in
SCIGROW.
The
available
aerobic
soil
metabolism
half­
life
for
oxadiazon
was
extremely
high.
For
FIRST,
stability
was
assumed,
while
the
extrapolated
value
of
841
days
was
used
in
SCIGROW.
The
modeling
results
associated
with
maximum
allowable
rate
per
year
(
4
lb
ai/
A
applied
twice
at
6
months
interval)
are
presented
in
Table
3.
Attached
to
this
memo
are
copies
of
the
original
printouts
generated
from
FIRST
and
SCIGROW
runs.

cc:
Nancy
McCarroll
(
HED)
62
Table
1.
Environmental
Fate
and
Other
Input
Parameters
for
the
Estimation
of
Oxadiazon
using
FIRST
Parameter
Value
Source
Water
Solubility
(
25

C)
1
ppm
One­
Liner
Hydrolysis
Half­
Life
(
pH
7)
stable
MRID
41863603
Aerobic
Soil
Metabolism
Half­
Life
(
from
6
values)
essentially
stable
MRID
42772801
Aerobic
Aquatic
Metabolism
Half­
life
not
available
N/
A
Aqueous
Photolysis
Half­
Life
2.75
days
MRID
41897201
Soil/
Water
Partition
Coefficient
(
Lowest
non­
sand
K
d)
16.9
MRID
41898202
Pesticide
is
Wetted­
In
Yes
Labels
PCA
(
turf)
0.87
Default
Depth
of
Incorporation
(
Broadcast)
0.0
inch
Labels
Table
2.
Environmental
Fate
Input
Parameters
for
the
Estimation
of
Oxadiazon
using
SCIGROW.

Parameter
Value
Source
Organic
Carbon
Partition
Coefficient
(
median
K
OC)
2376
MRID
41898202
Aerobic
Soil
Metabolism
Half­
Life
(
median)
841
days
MRID
42772801
Table
3.
Modeling
Results
for
Use
of
Oxadiazon
on
(
Turf)
Golf
Courses
Parameter
Value
Source
Application
Method
Ground
Spray
Labels
Application
Rate
4.0
lb
a.
i./
A
Registrant
Applications
Permitted
per
Year
2
Registrant***

Application
Interval
(
days)
182
Registrant
FIRST
1.0
Peak
Untreated
Water
Concentration
246
ppb
N/
A
FIRST
1.0
Annual
Average
Untreated
Water
Concentration
100
ppb
N/
A
SCIGROW
Ground
Water
Concentration
0.6
ppb
N/
A
***
The
Registrant
supports
multiple
applications,
at
lower
application
rates.
63
RESULTS
OBTAINED
USING
FIRST
RUN
No.
1
FOR
OXADIAZON
ON
Turf
(
Golf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
%
CROPPED
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
AREA
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000(
8.000)
2
182
16.9
1.0
GROUND(
6.4)
87.0
.0
FIELD
AND
RESERVOIR
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
RESERVOIR)
(
RES.­
EFF)
(
RESER.)
(
RESER.)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
UNTREATED
WATER
CONC
(
MICROGRAMS/
LITER
(
PPB))
Ver
1.0
MAY
1,
2001
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
DAY
(
ACUTE)
ANNUAL
AVERAGE
(
CHRONIC)
CONCENTRATION
CONCENTRATION
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
246.388
100.013
RESULTS
OBTAINED
USING
SCIGROW
RUN
No.
1
FOR
OXADIAZON
INPUT
VALUES
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
APPL
(#/
AC)
APPL.
URATE
SOIL
SOIL
AEROBIC
RATE
NO.
(#/
AC/
YR)
KOC
METABOLISM
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000
2
8.000
2376.0
841.0
GROUND­
WATER
SCREENING
CONCENTRATIONS
IN
PPB
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.592986
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
A=
836.000
B=
2381.000
C=
2.922
D=
3.377
RILP=
1.821
F=
­
1.130
G=
.074
URATE=
8.000
GWSC=
.592986
64
APPENDIX
F:
EXPOSURE
AND
RISK
CHARACTERIZATION
Risk
characterization
integrates
the
results
of
the
exposure
and
ecotoxicity
data
to
evaluate
the
likelihood
of
adverse
ecological
effects.
The
means
of
this
integration
is
called
the
quotient
method.
Risk
quotients
(
RQs)
are
calculated
by
dividing
exposure
estimates
by
acute
and
chronic
ecotoxicity
values:
RQ
=
exposure/
toxicity.
To
evaluate
the
potential
risk
to
aquatic
and
terrestrial
organisms
from
the
use
of
Oxadiazon,
risk
quotients
(
RQs)
are
calculated
from
the
ratio
of
estimated
environmental
concentrations
(
EECs)
to
ecotoxicity
values.

For
risk
assessments,
EFED
used
dosage
rate
information
obtained
from
SRRD
and
BEAD.
Since
most
of
the
use
is
on
golf
courses,
turf
was
chosen
to
represent
all
sites.

Terrestrial
and
aquatic
risk
assessments
were
based
on:
­
4
lb
ai/
A
liquid
and
granular
product
at
1
and
2
applications
per
year
with
a
six
month
reapplication
interval
­
2.4
lb
ai/
A
liquid
product
at
2
application
per
year
with
a
six
month
reapplication
interval
(
NOTE:
aquatic
risk
assessments
did
not
include
granular
formulations)

RQs
are
then
compared
to
levels
of
concern
(
LOC)
criteria
used
by
OPP
for
determining
potential
risk
to
nontarget
organisms
and
the
subsequent
need
for
possible
regulatory
action.
The
criteria
indicate
that
a
pesticide
used
as
directed
has
the
potential
to
cause
adverse
effects
on
nontarget
organisms.
LOCs
currently
address
the
following
risk
presumption
categories:
(
1)
acute
high
­­
potential
for
acute
risk
is
high;
regulatory
action
may
be
warranted
in
addition
to
restricted
use
classification,
(
2)
acute
restricted
use
­­
the
potential
for
acute
risk
is
high,
but
it
may
be
mitigated
through
restricted
use
classification,
(
3)
acute
species
­
the
potential
for
acute
risk
to
species
is
high,
and
regulatory
action
may
be
warranted,
and
(
4)
chronic
risk
­
the
potential
for
chronic
risk
is
high,
and
regulatory
action
may
be
warranted.
Currently,
EFED
does
not
perform
assessments
for
chronic
risk
to
plants,
acute
or
chronic
risks
to
nontarget
insects,
or
chronic
risk
from
granular/
bait
formulations
to
birds
or
mammals.

The
ecotoxicity
test
values
(
measurement
endpoints)
used
in
the
acute
and
chronic
risk
quotients
are
derived
from
required
studies.
Examples
of
ecotoxicity
values
derived
from
short­
term
laboratory
studies
that
assess
acute
effects
are:
(
1)
LC
50
(
fish
and
birds),
(
2)
LD
50
(
birds
and
mammals),
(
3)
EC
50
(
aquatic
plants
and
aquatic
invertebrates)
and
(
4)
EC
25
(
terrestrial
plants).
Examples
of
toxicity
test
effect
levels
derived
from
long­
term
laboratory
studies
that
assess
chronic
effects
are:
(
1)
LOAEC
(
birds,
fish,
and
aquatic
invertebrates)
and
(
2)
NOAEC
(
birds,
fish
and
aquatic
invertebrates).
Generally,
the
most
sensitive
species
tested
are
used.
The
NOAEC
is
used
as
the
ecotoxicity
test
value
in
assessing
chronic
effects
to
birds,
mammals,
fish,
and
aquatic
invertebrates.

Risk
presumptions
and
the
corresponding
RQs
and
LOCs,
are
tabulated
in
Table
1.
65
Table
1.
Risk
presumptions
for
terrestrial
organisms
Risk
Presumption
RQ
LOC
Birds
Acute
High
Risk
EEC1/
LC50
or
LD50/
sqft2
or
LD50/
day3
0.5
Acute
Restricted
Use
EEC/
LC50
or
LD50/
sqft
or
LD50/
day
(
or
LD50
<
50
mg/
kg)
0.2
Acute
Species
EEC/
LC50
or
LD50/
sqft
or
LD50/
day
0.1
Chronic
Risk
EEC/
NOAEC
1
Wild
Mammals
Acute
High
Risk
EEC/
LC50
or
LD50/
sqft
or
LD50/
day
0.5
Acute
Restricted
Use
EEC/
LC50
or
LD50/
sqft
or
LD50/
day
(
or
LD50
<
50
mg/
kg)
0.2
Acute
Species
EEC/
LC50
or
LD50/
sqft
or
LD50/
day
0.1
Chronic
Risk
EEC/
NOAEC
1
1
abbreviation
for
Estimated
Environmental
Concentration
(
ppm)
on
avian/
mammalian
food
items
2
mg/
ft2
3
mg
of
toxicant
consumed/
day
LD50
*
wt.
of
bird
LD50
*
wt.
of
bird
Risk
presumptions
for
aquatic
organisms
Risk
Presumption
RQ
LOC
Acute
High
Risk
EEC1/
LC50
or
EC50
0.5
Acute
Restricted
Use
EEC/
LC50
or
EC50
0.1
Acute
Species
EEC/
LC50
or
EC50
0.05
Chronic
Risk
EEC/
NOAEC
1
1
EEC
=
(
ppm
or
ppb)
in
water
66
Risk
presumptions
for
plants
Risk
Presumption
RQ
LOC
Plant
Inhabiting
Terrestrial
and
Semi­
Aquatic
Areas
Acute
High
Risk
EEC1/
EC25
1
Acute
Species
EEC/
EC05
or
NOAEC
1
Aquatic
Plants
Acute
High
Risk
EEC2/
EC50
1
Acute
Species
EEC/
EC05
or
NOAEC
1
1
EEC
=
lbs
a.
i./
A
2
EEC
=
(
ppb
or
ppm)
in
water
67
Table
2.
Selection
of
Toxicological
Endpoints
Used
to
Determine
Risk
Quotients
(
RQs)

Type
Of
Toxicity
Organism
Species
Toxicological
Endpoint
Oral
Acute
Bird
Mallard
1040
mg/
kg
Dietary
Bobwhite/
Mallard
>
5000
ppm
Chronic
Bobwhite
500
ppm
1
Oral
Acute
Mammal
Rat
>
5000
mg/
kg
Chronic
Rat
100
ppm
2
Acute
Freshwater
Fish
Rainbow
trout/
Bluegill
0.88
ppm
Chronic
Rainbow
trout
0.88
ppb
3
Acute
Freshwater
Invertebrates
Daphnid
2.18
ppm
Chronic
Daphnid
0.03
ppm
Acute
Estuarine
Fish
Sheepshead
Minnow
1.5
ppm
Chronic
Sheepshead
Minnow
0.0015
ppm4
Acute
Estuarine
Invertebrates
Mysid
0.27
ppm
Chronic
Mysid
0.0037
ppm4
Acute
Aquatic
Plants
(
vascular)

Aquatic
Plants
(
Nonvascular)
duckweed
marine
diatom
EC50
=
41
ppb;
NOAEC
=
<
8
ppb
EC50
=
5.2
ppb
1
No
effects
on
any
reproductive
parameter
or
viability
of
of
F1
offspring
at
the
highest
dose
tested,
1000
ppm;
however
due
to
excessive
mortality
(
33%)
of
adult
female
birds
in
that
dose
level,
a
NOAEC
for
chronic
effects
was
set
at
500
ppm.
2
Based
on
LOAEL
of
>
38
mg/
kg/
day
for
inactive
mammary
tissue
and
fetal/
pup
death
observed
in
the
one
year
range­
finding
test
of
a
rat
reproduction
study.
NOAEC
>
100
ppm.
3
Rainbow
trout
was
more
sensitive
than
the
fathead
minnow
(
fathead
minnow
NOAEC=
33
ppb).
4
Extrapolation
from
acute/
chronic
ratio.
68
Table
6.
Environmental
Fate
Input
Parameters
for
GENEEC
2.0.

Chemical
Oxadiazon
PC
Code
109001
Water
Solubility
(
25

C)
1
ppm
Hydrolysis
Half­
Life
(
pH
7)
stable
Aerobic
Soil
Metabolism
Half­
Life
stable
Aerobic
Aquatic
Metabolism
Half­
life
not
available
Photolysis
Half­
Life
2.75
days
Soil/
Water
Equilibrium
Partition
Coefficient
(
Kd)
16.91
Depth
of
Incorporation
(
Broadcast)
0.0
in.

Wetted­
In
Yes
Table
7.
Modeling
Results
for
Use
on
Turf
Ground
spray1
granular
Application
Rate
2.0
3.0
4.0
4.0
4.0
Application
Frequency
1
1
1
2
2
Application
Interval
(
days)
N/
A
N/
A
182
182
182
GENEEC
2.0
Peak
EEC
44
67
89
173
150
21­
Day
EEC
43
65
87
170
147
60­
Day
EEC
42
63
84
163
142
3.
Low
boom
ground
sprayer
with
fine
spray
quality
(
EFED
defaults),
no
buffer
(
no
spray
zone).
69
APPENDIX
G:
ENVIRONMENTAL
FATE
AND
ECOLOGICAL
EFFECTS
DATA
REQUIREMENTS
Table
of
Data
Requirements
of
Ecological
Effects
for
Oxadiazon
Guideline
#
Data
Requirement
Is
Data
Requirement
Satisfied?
MRID
#'
s
Study
Classification
71­
1
850.2100
Avian
Oral
LD50
yes
41610101
core
71­
2
850.2200
Avian
Dietary
LC50
yes
41610102
41610103
core
core
71­
4
850.2300
Avian
Reproduction
yes
41993201
41993202
supplemental
core
72­
1
850.1075
Freshwater
Fish
LC50
yes
42350601
42330401
core
core
72­
2
850.1010
Freshwater
Invertebrate
Acute
LC50
yes
41784301
core
72­
3(
a)
850.1075
Estuarine/
Marine
Fish
LC50
yes
42615801
core
72­
3(
b)
850.1025
Estuarine/
Marine
Mollusk
EC50
yes
42570301
core
72­
3(
c)
850.1035
850.1045
Estuarine/
Marine
Shrimp
EC50
yes
42615802
core
72­
4(
a)
850.1400
Estuarine
Fish
Early
Life­
Stage
no
72­
4(
b)
850.1300
850.1350
Estuarine/
Marine
Invertebrate
Life­
Cycle
no
72­
5
850.1500
Freshwater
Fish
Full
Life­
Cycle
na
­
­

122­
1(
a)
850.4100
Seed
Germ./
Seedling
Emergence
no
­
­

122­
1(
b)
850.4150
Vegetative
Vigor
no
­
­
70
122­
2
850.4400
Aquatic
Plant
Growth
partially
­
­

123­
1(
a)
850.4225
Seed
Germ./
Seedling
Emergence
no
123­
1(
b)
850.4250
Vegetative
Vigor
no
123­
2
850.4400
Aquatic
Plant
Growth
partially
5
41610105
41610106
41610106
41610108
core
141­
1
850.3020
Honey
Bee
Acute
Contact
LD50
yes
4268301
core
141­
2
850.3030
Honey
Bee
Residue
on
Foliage
not
required
70­
1
Acute
and
Chronic
Sediment
Toxicity
Testing
no6
70­
1
Aquatic
Phototoxicity
Studies
no
1
Although
the
mallard
study
was
supplemental
since
a
NOAEC
was
not
established,
the
study
does
not
have
to
be
repeated;
the
bobwhite
was
more
sensitive
and
was
used
for
risk
assessment
purposes.

2
Early­
life
stage
fish
testing
with
an
estuarine
species
is
required.
The
raw
data
for
the
rainbow
trout
study
MRID
41811601
must
be
submitted.
This
information
was
requested
in
1997
under
D165510.

4
The
rates
used
should
be
low
enough
to
elicit
an
NOAEC
or
allow
for
accurate
estimation
of
the
EC05
for
all
measured
parameters.
The
measured
endpoints
should
include:
shoot
length,
root
length
and/
or
height,
and
a
phytotoxic
rating
of
the
visible
effects.
Testing
must
be
conducted
with
a
liquid
typical
end­
use
product,
rather
than
technical
product,
due
to
the
insolubility
of
the
material
and
since
historically,
plant
species
have
been
found
to
be
more
sensitive
to
the
end­
use
product,
than
technical.
Concentrations
must
be
measured,
and
results
must
be
based
on
measured
concentrations.
The
nominal
concentrations
used
in
statistical
analyses
most
likely
did
not
represent
actual
exposure.
This
information
was
requested
in
1995
under
D166982.

5
A
freshwater
blue­
green
algae
(
Anabaena
flos­
aquae)
is
required;
the
study
submitted
(
MRID
41610104)
was
invalid.

6
The
high
KOC
of
oxadiazon,
combined
with
the
high
persistance
exhibited
in
the
aerobic
soil
metabolism,
as
well
as
the
anaerobic
aquatic
metabolism
(>>
10
days)
trigger
the
requirement
of
a
Chronic
Sediment
Toxicity
Testing
with
both
Hyalella
azteca
and
Chironomus
tentans.
2
Waived
due
to
the
relatively
low
vapor
pressure
for
oxadiazon
(
1.00x10­
6
mm
Hg).

3Satisfied
by
submission
of
an
Anaerobic
Aquatic
Metabolism
study.

71
Table
of
Data
Requirements
of
Environmental
Effects
for
Oxadiazon
Guideline
#
Data
Requirement
Is
Data
Requirement
Satisfied?
MRID
#'
s
Study
Classificatio
n
161­
1
835.2120
Hydrolysis
Yes
41863603
acceptable
161­
2
835.2240
Photodegradation
in
Water
Yes
41897201
acceptable
161­
3
835.2410
Photodegradation
on
Soil
Yes
41898201
acceptable
161­
4
835.2370
Photodegradation
in
Air
waived2
N/
A
N/
A
162­
1
835.4100
Aerobic
Soil
Metabolism
Yes
42772801
acceptable
162­
2
835.4200
Anaerobic
Soil
Metabolism
Yes3
NA
N/
A
162­
3
835.4400
Anaerobic
Aquatic
Metabolism
Yes
42773802
supplemental
162­
4
835.4300
Aerobic
Aquatic
Metabolism
not
required
N/
A
N/
A
163­
1
835.1240
835.1230
Leaching­
Adsorption/
Desorption
Yes
44555608
,
41898202
acceptable,

supplemental
163­
2
835.1410
Laboratory
Volatility
waived1
N/
A
N/
A
163­
3
835.8100
Field
Volatility
waived1
N/
A
N/
A
164­
1
835.6100
Terrestrial
Field
Dissipation
Yes
41767401
acceptable
164­
2
835.6200
Aquatic
Field
Dissipation
not
required
N/
A
N/
A
164­
3
835.6300
Forestry
Dissipation
not
required
N/
A
N/
A
72
164­
4
835.6400
Combination
Products
and
Tank
Mixes
Dissipation
not
required
N/
A
N/
A
165­
4
850.1730
Accumulation
in
Fish
Yes
42226701
acceptable
165­
5
850.1950
Accumulation­
aquatic
non­
target
not
required
N/
A
N/
A
166­
1
835.7100
Ground
Water­
small
prospective
not
required
N/
A
N/
A
201­
1
840.1100
Droplet
Size
Spectrum
reserved
N/
A
N/
A
202­
1
840.1200
Drift
Field
Evaluation
reserved
N/
A
N/
A
73
APPENDIX
H:
QUALITATIVE
USE
ASSESSMENT
Case
No.:
2485
PC
Code:
109001
Date:
01­
10­
01
Analyst:
Stephen
Smearman
Oxadiazon
is
a
selective
preemergence
and
early
post
emergence
herbicide
used
primarily
to
control
annual
grasses
and
broadleaf
weeds.
The
tradename
for
Oxadiazon
in
the
US
is
Ronstar
(
formerly
Chipco
Ronstar)
and
formulations
are
available
as
emulsifiable
concentrates,
granules,
flowable
and
wetable
powders.

Based
upon
the
available
EPA
data
and
other
pesticide
usage
survey
information
for
Oxadiazon
on
all
sites
for
the
years
1989
through
1999,
an
annual
estimate
of
Oxadiazon's
total
usage
on
all
sites
averaged
249,000
pounds
of
active
ingredient
(
a.
i.)
on
an
average
of
52,000
acres
treated
over
the
last
10
years.
Most
of
the
acreage
is
treated
with
up
to
2.4
pounds
of
a.
i.
per
acre
owing
most
of
the
usage
applies
to
golf
courses
which
based
on
reported
usage
has
higher
application
rates
than
other
uses.
Oxadiazon's
largest
markets
in
terms
of
total
pounds
of
active
ingredient
is
allocated
to
golf
courses
(
65%).
The
remaining
usage
is
primarily
for
horticultural/
nursery
uses
and
on
processed
tomatoes
(
22%).
Other
reported
uses
include
potatoes
and
barley
which
accounts
for
an
respective
1.5%
and
less
than
1%
of
the
total
pounds
a.
i.
annually.
However,
there
are
no
tolerances
nor
labeled
uses
for
these
site
and
therefore
should
not
be
considered
during
risk
assessment.
However,
there
is
international
reported
use
of
Oxadiazon
on
rice
in
China
and
on
cotton
in
Mexico
and
Sudan.

Additional
estimates
of
total
acres
grown
and
total
acres
treated
for
the
non­
crop
sites
of
road
right
of
ways
(
ROW),
landscape
maintenance,
horticultural/
nursery
and
park
uses
are
not
currently
available
although
there
is
estimates
of
pounds
of
a.
i.
applied.
The
following
table
illustrates
the
usage
of
Oxadiazon.
74
USAGE
OF
OXADIAZON
Site
Acres
Grown
(
000)
Acres
Treated
(
000)
%
of
Crop
Treated
LB
AI
Applied
(
000)
Average
Application
Rate
Wtd
Avg
Est
Max
Wtd
Avg
Est
Max
Wtd
Avg
Est
Max
lb
ai/
acre/
yr
#
appl
/
yr
lb
ai/
A/
appl
*
Potatoes
1,373
2
4
0%
0%
4
8
2.0
1.0
2.0
*
Barley
7,326
0
1
0%
0%
0
1
1.0
1.0
1.0
Lots/
Farmsteads/
etc
56,000
1
3
0%
0%
1
4
1.3
1.0
1.3
Golf
Courses
1,618
49
98
3%
6%
160
235
2.4
1.0
2.4
Landscape
Mainten
­
­
­
­
­
12
24
3.0
­
­

Rights
of
Way
­
­
­
­
­
5
10
­
­
­

Parks
­
­
­
­
­
11
22
­
­
­

Horticultural
Nurseries
­
­
­
­
­
56
112
4.0
­
­

Total
51.915
106
249.03
416
COLUMN
HEADINGS
Wtd
Avg
=
Weighted
average­­
the
most
recent
years
and
more
reliable
data
are
weighted
more
heavily.
Est
Max
=
Estimated
maximum,
which
is
estimated
from
available
data.
Average
application
rates
are
calculated
from
the
weighted
averages.

NOTES
ON
TABLE
DATA
Usage
data
primarily
covers
1988
­
1998.
Calculations
of
the
above
numbers
may
not
appear
to
agree
because
they
are
displayed
as
rounded
to
the
nearest
1000
for
acres
treated
or
lb.
a.
i.
(
Therefore
0
=
<
500)
to
the
nearest
whole
percentage
point
for
%
of
crop
treated.
(
Therefore
0%
=
<
0.5%)
*
=
Available
EPA
sources
indicate
that
usage
is
observed
for
potatoes
and
barley
in
the
reported
data
for
this
site.
However,
there
are
no
tolerances
or
labeled
uses
for
these
site.
Reason
for
reported
usage
is
undetermined
and
therefore
usage
for
these
sites
should
not
be
used
for
risk
assessment.
­
=
missing
information
or
lack
of
confidence
in
the
data
to
determine
an
accurate
estimate
of
usage.
However,
these
sites
were
included
in
the
table
because
of
indicated
usage.

SOURCES:
EPA
data,
1988­
98;
USDA,
NASS,
1999
75
APPENDIX
I.
GENEEC
2.0
INPUT
PARAMETERS,
RESULTS,
AND
OUTPUTS
Environmental
Fate
Input
Parameters
for
GENEEC
2.0.

Chemical
Oxadiazon
PC
Code
109001
Water
Solubility
(
25

C)
1
ppm
Hydrolysis
Half­
Life
(
pH
7)
stable
Aerobic
Soil
Metabolism
Half­
Life
stable
Aerobic
Aquatic
Metabolism
Half­
life
not
available
Photolysis
Half­
Life
2.75
days
Soil/
Water
Equilibrium
Partition
Coefficient
(
K
d)
16.91
Depth
of
Incorporation
(
Broadcast)
0.0
in.

Wetted­
In
Yes
Table
2.
Modeling
Results
for
Use
on
Turf
Ground
spray1
granular
Application
Rate
2.0
3.0
4.0
4.0
4.0
Application
Frequency
1
1
1
2
2
Application
Interval
(
days)
N/
A
N/
A
182
182
182
GENEEC
2.0
Peak
EEC
44
67
89
173
150
21­
Day
EEC
43
65
87
170
147
60­
Day
EEC
42
63
84
163
142
4.
Low
boom
ground
sprayer
with
fine
spray
quality
(
EFED
defaults),
no
buffer
(
no
spray
zone).
76
RUN
No.
1
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000(
8.000)
2
182
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
173.14
172.44
169.50
163.00
158.23
RUN
No.
2
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
2.000(
4.000)
2
42
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
88.20
87.84
86.34
83.03
80.60
77
RUN
No.
3
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
3.000(
6.000)
2
182
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
129.85
129.33
127.12
122.25
118.67
RUN
No.
4
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000(
8.000)
2
182
16.9
1.0
GRANUL(
.0)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
150.41
149.80
147.25
141.60
137.46
78
RUN
No.
1
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
2.000(
2.000)
1
1
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
44.39
44.21
43.46
41.79
40.57
RUN
No.
1
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
3.000(
3.000)
1
1
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
66.59
66.32
65.19
62.69
60.85
79
RUN
No.
1
FOR
Oxadiazon
ON
Turf
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
NO­
SPRAY
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
(
FT)
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000(
4.000)
1
1
16.9
1.0
GRHIFI(
6.6)
.0
.0
FIELD
AND
STANDARD
POND
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
POND)
(
POND­
EFF)
(
POND)
(
POND)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
0
N/
A
2.75­
341.00
.00
341.00
GENERIC
EECs
(
IN
MICROGRAMS/
LITER
(
PPB))
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
MAX
4
DAY
MAX
21
DAY
MAX
60
DAY
MAX
90
DAY
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
AVG
GEEC
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
88.79
88.43
86.92
83.59
81.14
4Matringe,
M.,
J.­
M.
Camadro,
P.
Labbe,
and
R.
Scalla.
1989.
Protoporphyrinogen
oxidase
as
a
molecular
target
for
diphenyl
ether
herbicides.
Biochem.
J.
260:
231­
235.

5Birchfield,
N.
B.,
and
J.
E.
Casida.
1997.
Protoporphyrinogen
oxidase
of
mouse
and
maize:
Target
site
selectivity
and
thiol
effects
on
peroxidizing
herbicide
action.
Pesticide
Biochemistry
and
Physiology
57,
36­
43.

6Halling,
B.
P.,
D.
A.
Yuhas,
V.
F.
Fingar,
and
J.
W.
Winkleman.
1994.
"
Protoporphyrinogen
oxidase
inhibitors
for
tumor
therapy"
in
Porphyric
Pesticides:
Chemistry,
Toxicology,
and
Pharmaceutical
Applications,
(
S.
O.
Duke
and
C.
A.
Rebeiz,
Eds.)
pp.
280­
290,
American
Chemical
Society
Symposium
Series
559,
Am.
Chem.
Soc.,
Washington,
D.
C.,
1994.

7Birchfield,
N.
B.
Protoporphyrinogen
Oxidase
as
a
Herbicide
Target:
Characterization
of
the
[
3H]
Desmethylflumipropyn
Binding
Site.
Dissertation.
University
of
California,
Berkeley.
1996.

80
APPENDIX
J.
PHOTOXICITY
STUDY
PROTOCOL
for
LIGHT­
DEPENDENT
PEROXIDIZING
HERBICIDES
The
light­
dependent
peroxidizing
herbicides
(
LDPHs)
are
a
growing
class
of
weed
control
chemicals
(
see
partial
listing
attached).
They
act
in
plants
by
inhibiting
the
enzyme
protoporphyrinogen
oxidase
(
protox),
which
is
the
last
common
enzyme
in
the
heme
and
chlorophyll
biosynthetic
pathways.
4
Protox
exists
in
both
plants
and
animals
and
the
enzyme
from
both
sources
has
been
shown
to
be
highly
sensitive
to
many
LDPHs.
5
LDPH
protox
inhibition
in
plants
results
in
a
rapid
accumulation
of
protoporphyrin
IX,
a
phototoxic
heme
and
chlorophyll
precursor.
In
the
presence
of
light,
protoporphyrin
IX
is
a
powerful
generator
of
singlet
oxygen
which
in
plants
causes
lipid
membrane
peroxidation
leading
to
a
rapid
loss
of
turgidity
and
foliar
burns.
LDPH
exposure
in
mammals
has
been
shown
to
result
in
excretion
of
porphyrins
in
urine
(
porphynuria)
and
feces,
increased
liver
weight,
elevated
blood
porphyrin
levels,
developmental
abnormalities,
and
cancer.
Humans
with
a
hereditary
protox
disorder
(
variegate
porphyria)
which
results
in
lowered
protox
activity
exhibit
many
symptoms
similar
to
LDPH
exposure
in
addition
to
photosensitivity.
However,
photosensitivity
is
not
a
commonly
reported
symptom
of
LDPH
exposure
in
animals.

An
LDPH­
induced
occurrence
of
phototoxicity
in
rats6
and
increased
cytotoxicity
to
human
skin
cells
grown
in
culture
in
the
presence
of
light
and
an
LDPH7
have
been
reported
but
many
other
LDPH
toxicity
studies
make
no
mention
of
phototoxicity
in
animals.
The
scarcity
of
phototoxicity
data
in
animals
could
result
from
physiological
or
biochemical
distinctions
from
plants.
For
instance,
animals
exposed
to
LDPHs
may
not
normally
accumulate
protoporphyrin
IX
in
their
epidermis.
However,
phototoxicity
may
not
be
reported
in
many
LDPH
toxicity
tests
because
of
relatively
low
light
conditions
in
laboratories
and/
or
protection
afforded
by
the
animals'
fur
or
feathers.
Animals
without
fur
or
feathers
existing
in
sunny
environments
would
be
expected
to
be
at
highest
risk
for
potential
phototoxic
effects.

The
Aquatic
Biology
Tech
Team
(
ABTT)
recommends
that
phototoxicity
studies
be
conducted
on
8American
Society
for
Testing
and
Materials.
1994.
Standard
guide
for
conducting
the
frog
embryo
teratogenesis
assay­
Xenopus.
E
1439­
91.
In
Annual
Book
of
ASTM
Standards,
Vol
11.5,
pp.
825­
835.
Philadelphia,
PA.

81
herbicides
with
this
mode
of
action
to
determine
if
animals
exposed
to
LDPHs
and
intense
light
(
similar
to
sunlight)
show
increased
toxicity
relative
to
controls
exposed
to
LDPHs
and
low
intensity
light.
The
results
of
these
studies
will
help
to
determine
if
animals
that
are
exposed
to
sunlight
in
LDPH
use
areas
are
at
higher
risk
than
guideline
toxicity
studies
suggest.

The
ABTT
is
requesting
that
a
LDPH
phototoxicity
protocol
be
submitted
for
review
and
agreement
by
EFED
and
the
registrant
prior
to
study
initiation.
Protocols
for
standard
toxicity
tests
have
also
been
published.
8
In
nature,
fish
and
other
aquatic
organisms
are
expected
to
be
exposed
to
LDPHs
through
run­
off
and
spray
drift.
Aquatic
organisms
inhabiting
small,
shallow
water
bodies,
exposed
to
high
levels
of
solar
radiation
would
be
expected
to
be
at
greatest
risk
for
potential
phototoxic
effects.
Therefore,
the
ABTT
is
requesting
a
small
fish
species
be
used
in
a
phototoxicity
assay
to
assess
the
potential
of
light
to
increase
LDPH
toxicity.

The
ABTT
requests
that
the
study
adequately
address
the
following
issues
and
suggests
the
paper,
"
Photoenhanced
Toxicity
of
a
Carbamate
Insecticide
to
Early
Life
Stage
Anuran
Amphibians",
5
and
other
studies
in
the
peer­
reviewed
scientific
literature
serve
as
sources
of
additional
guidance:

Species
The
fathead
minnow
may
be
an
appropriate
test
species
because
of
existing
toxicity
protocols
which
may
be
adapted
for
this
study.

Exposure
duration
A
subchronic
exposure
duration
would
be
adequate
for
proof
of
principle.
A
single
exposure
may
not
allow
adequate
time
for
porphyrin
accumulation,
however,
a
life­
cycle
is
not
necessary
to
identify
a
phototoxic
effect.

Dosing
A
range
finding
study
should
be
conducted
under
defined
low
light
conditions
to
identify
an
LC
50
value
and
lower
dose
levels
expected
to
be
similar
to
controls.
Doses
used
in
the
phototoxicity
study
should
not
be
expected
to
result
in
significant
mortality
in
low
light
controls.
Dissolved
concentrations
of
the
test
chemical
should
be
confirmed
by
an
appropriate
analytical
method.

Endpoints
Behavioral
observations
should
be
made
in
addition
to
measurements
of
mortality,
growth,
weight,
morphology,
and
appearance.
Ideally,
measurements
of
protoporphyrin
and
heme
concentrations
in
the
blood
and
protox
activity
in
the
liver
of
each
test
organisms
should
be
made.

Light
sources
Artificial
light
may
be
preferred
to
natural
light
that
will
vary
in
different
regions
and
seasons
as
well
as
82
with
weather.
If
artificial
light
is
used,
the
light
should
resemble
full,
natural
sunlight
as
closely
as
possible,
particularly
around
400
nm.
The
most
important
wavelength
for
porphyrin
induced
phototoxicity
in
~
400
nm.
No
matter
what
the
light
source,
the
duration
and
intensity
of
UV
and
visible
light
should
be
reported
at
all
wavelengths
(
200­
800
nm).
At
this
point
EFED
does
not
have
a
specific
recommendation
for
an
artificial
light
source.

Dark,
light,
and
positive
controls
As
this
study
is
intended
to
identify
potential
effects
of
light
on
LDPH
toxicity,
an
appropriate
study
protocol
should
include
a
dark,
or
low
light,
control
group.
Another
group
not
exposed
to
chemicals
but
exposed
to
full
light
should
be
included
(
a
full
light
control).
In
addition
to
the
dark
and
light
controls,
a
positive
control
group
using
protoporphyrin
IX
may
be
useful.

Exposure
chambers
and
light
filters
Light
intensity
should
be
measured
inside
test
chambers
if
glass
or
any
other
material
is
placed
between
the
light
source
and
the
test
animals.
Any
filters
should
be
cured
under
the
study
light
for
72­
hours
prior
to
study
initiation
to
ensure
consistent
transmittance.
83
ATTACHMENT
1.

The
following
list
of
herbicides
are
believed
to
act
by
inhibiting
protoporphyringen
oxidase
in
the
heme
and
chlorophyll
biosynthetic
pathway.

acifluorfen
azafenidin
carfentrazone­
ethyl
flumiclorac­
pentyl
flumioxazin
fluthiacet­
methyl
fomesafen
lactofen
oxadiargyl
oxadiazon
oxyfluorfen
sulfentrazone
thidiazimin