1
Napropamide
Overview
of
Risk
Assessment
March,
16
2005
Introduction
This
document
summarizes
EPA's
human
health,
environmental
fate,
and
ecological
risk
findings
for
the
pesticide
napropamide.
These
findings
are
presented
fully
in
the
human
health
risk
assessment
document,
"
Napropamide:
Revised
HED
Chapter
of
the
Reregistration
Eligibility
Decision
Document,"
dated
February
23,
2005;
and,
"
EFED
risk
assessment
for
the
Napropamide
Reregistration
Eligibility
Document,"
dated
March
1,
2005.
The
purpose
of
this
overview
is
to
present
the
key
features
and
findings
of
these
risk
assessments
in
order
to
assist
interested
parties
in
better
understanding
the
conclusions
reached
in
the
assessments.
This
overview
was
developed
in
response
to
comments
and
requests
from
the
public
that
risk
assessments
were
difficult
to
understand,
that
they
were
too
lengthy,
and
that
it
was
not
easy
to
compare
the
assessments
for
different
chemicals
due
to
the
use
of
different
formats.

The
napropamide
risk
assessments
and
additional
supporting
documents
are
posted
on
EPA's
Pesticide
Docket
website
(
http://
www.
epa.
gov/
edockets)
under
docket
number
OPP­
2004­
0162
for
public
viewing.
Public
comments
on
the
risk
assessments
will
be
invited
for
60
days.
During
the
comment
period,
EPA
will
continue
its
ongoing
efforts
to
consult
with
other
government
agencies
and
stakeholders
on
the
pesticide's
uses
and
risk
management
options.
After
the
comment
period
closes,
EPA
will
consider
the
comments
received,
continue
dialogue
with
other
government
agencies
and
stakeholders
as
needed,
and
develop
a
risk
management
decision.

Unlike
other
pesticides
for
which
EPA
has
followed
a
cumulative
risk
approach
based
on
a
common
mechanism
of
toxicity,
EPA
has
not
made
a
common
mechanism
of
toxicity
finding
for
napropamide
and
other
substances,
and
napropamide
does
not
appear
to
produce
a
toxic
metabolite
produced
by
other
substances.
For
the
purposes
of
this
risk
assessment
action,
therefore,
EPA
has
not
assumed
that
napropamide
has
a
common
mechanism
of
toxicity
with
other
substances.
For
information
regarding
EPA's
efforts
to
determine
which
chemicals
have
a
common
mechanism
of
toxicity
and
to
evaluate
the
cumulative
effects
of
such
chemicals,
see
the
policy
statements
released
by
EPA's
Office
of
Pesticide
Programs
concerning
common
mechanism
determinations
and
procedures
for
cumulating
effects
from
substances
found
to
have
a
common
mechanism
on
EPA's
website
at
http://
www.
epa.
gov/
pesticides/
cumulative/.
2
Use
Profile
Use
Sites:

$
Napropamide
is
a
selective
preemergence
herbicide
belonging
to
the
amide
class
of
pesticides.
It
controls
weeds
by
preventing
root
cell
elongation,
thus
disrupting
the
growth
process
during
germination.

$
Napropamide
is
registered
to
control
broadleaf
weeds
and
annual
grasses
on
numerous
food/
feed
and
non­
food/
feed
use
sites,
including
fruits
and
nuts,
vegetables,
ornamentals,
turf/
lawns,
forestry
sites
and
tobacco.

Formulations:

$
Napropamide
is
formulated
as
dry
flowables,
granulars
and
liquid
formulations.

Method
of
Application:

$
Napropamide
is
applied
at
rates
between
2
and
6
pounds
active
ingredient
per
acre
(
lbs
a.
i/
A)
on
all
crops/
sites
except
cranberries,
where
applications
at
up
to
15
lbs
a.
i./
A
are
allowed.
Aerial
applications
are
labeled
for
cranberries
only.
Applications
for
all
other
uses
are
made
using
ground
equipment,
including
ground
boom
and
hand­
held
sprayers,
granular
application
equipment,
and
chemigation
equipment.

Use
Summary:

$
According
to
usage
data,
the
highest
percent
crop
treated
are
on
cranberries,
strawberries,
tomatoes,
peppers,
tobacco,
artichokes,
and
eggplant.

$
Technical
Registrant:
United
Phosphorus
Inc.
3
Human
Health
Risk
Assessment
Dietary
(
Food
+
Water)
Risk
Dietary
risk
assessment
incorporates
both
exposure
to
and
toxicity
of
a
given
pesticide.
The
risk
is
expressed
as
a
percentage
of
a
maximum
acceptable
dose
(
i.
e.,
the
dose
which
will
result
in
no
unreasonable
adverse
health
effects).
This
dose
is
referred
to
as
the
population
adjusted
dose
(
PAD).
The
PAD
is
equivalent
to
the
Reference
Dose
(
RfD)
divided
by
the
special
FQPA
Safety
Factor.
EPA
is
concerned
when
estimated
dietary
risk
exceeds
100%
of
the
PAD.

Drinking
water
exposure
to
pesticides
can
occur
through
groundwater
and
surface
water
contamination.
EPA
considers
drinking
water
risks
and
uses
either
modeling
or
monitoring
data,
if
available,
to
estimate
those
risks.
Modeling
is
carried
out
in
tiers
of
further
refinement,
but
is
designed
to
provide
a
high­
end
estimate
of
exposure.

Acute
Dietary
Risk
No
toxicological
endpoint
was
selected
for
the
acute
dietary
exposure
scenario,
since
an
endpoint
attributable
to
a
single
exposure
was
not
identified
from
the
available
database.
Therefore,
no
acute
dietary
assessment
was
performed.

Chronic
Dietary
Risk
(
Food
+
Water)

A
risk
estimate
that
is
less
than
100%
of
the
chronic
PAD
(
the
dose
at
which
an
individual
could
be
exposed
over
the
course
of
a
lifetime
and
no
adverse
health
effects
would
be
expected)
does
not
exceed
the
Agency's
risk
concern.
The
cPAD
is
the
chronic
reference
dose
(
cRfD)
adjusted
for
the
FQPA
Safety
Factor.

Table
1.
Napropamide
:
Summary
of
the
Toxicology
Endpoint
Selection
Chronic
Dietary
Endpoint
Exposure
Scenario
Dose
&
Uncertainty
Factors
Endpoint
Study
Chronic
Dietary
NOAEL=
12
mg/
kg
Decreased
weight
gain
in
females
and
an
increased
incidence
of
liver
lesions
in
males
at
a
LOAEL
of
48/
55
mg/
kg/
day
(
m/
f)
Rat
Chronic/
Oncogenicity
Study.
MRID
Nos.
42189102
&
43068801
UF
=
100x
FQPA
Safety
Factor
=
1x
Chroinc
PAD
=
0.12
mg/
kg/
day
4
Toxicity
$
Napropamide
did
not
cause
developmental
toxicity
in
either
rats
or
rabbits
and
did
not
adversely
affect
reproductive
parameters
in
rats
over
three
generations.
There
is
no
quantitative
or
qualitative
evidence
of
increased
susceptibility
of
rat
or
rabbit
fetuses
after
in
utero
and/
or
postnatal
exposure
to
napropamide
in
the
developmental
and
reproduction
studies.
Dose­
response
relationships
are
well­
characterized
and
clear.
No
Observable
Adverse
Effect
Levels
(
NOAELs)/
Lowest
Observable
Adverse
Effect
Levels
(
LOAELs)
have
been
identified
for
the
critical
effects.
Therefore,
the
special
FQPA
safety
factor
for
napropamide
has
been
reduced
to
1X.

$
No
evidence
of
neurotoxicity
was
observed
in
any
study.
Based
on
the
weight
of
evidence,
a
developmental
neurotoxicity
(
DNT)
study
is
not
required
for
napropamide.

$
The
chronic
RfD
is
calculated
to
be
0.12
mg/
kg/
day
based
on
the
NOAEL
of
12
mg/
kg/
day
and
uncertainty
factors
of
10x
for
interspecies
and
10x
for
intraspecies.
Because
the
FQPA
safety
factor
was
reduced
to
1x,
the
chronic
RfD
is
equal
to
the
chronic
PAD.
The
chronic
Population
Adjusted
Dose
(
cPAD)
is
0.12
mg/
kg/
day.

Dietary
(
Food)

$
A
chronic
dietary
risk
assessment
was
conducted
using
the
Lifeline
TM
Model
Version
2.0
which
uses
food
consumption
data
from
the
United
States
Department
of
Agriculture's
(
USDA)
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII)
from
1994­
1996
and
1998.
In
this
analysis
the
chronic
dietary
exposure
and
risk
estimates
resulting
from
food
intake
were
determined
for
the
general
U.
S.
population
and
various
population
subgroups.

$
This
chronic
analysis
assumed
100%
crop
treated
and
tolerance­
level
residues
(
Tier
1)
for
all
commodities.
Processing
factors
were
based
on
the
results
of
processing
studies
for
commodities
where
such
data
were
available
(
apple
juice,
citrus
juice/
oil,
figs,
grape
juice/
raisins,
prunes
and
tomato
juice/
puree/
paste).
For
all
other
commodities,
default
processing
factors
were
used.

Dietary
(
Drinking
Water)

$
Napropamide
is
persistent
but
not
particularly
mobile
and
therefore
not
expected
to
pose
a
significant
risk
of
ground
water
contamination.
Surface
water
contamination
is
possible
through
run­
off
from
treated
fields.

$
Drinking
water
concentrations
for
ground
water
were
calculated
using
model
estimates
from
the
Tier
I
model
SCI­
GROW
2.2
model.
Drinking
water
concentrations
for
surface
water
were
estimated
using
the
Tier
II
PRZM
version
3.12/
EXAMS
model.
5
$
Potential
exposure
to
napropamide
from
drinking
water
derived
from
groundwater
results
in
a
chronic
drinking
water
estimated
concentration
(
DWEC)
of
4.5
ppb.
For
surface
water,
the
DWEC
is
0.5
ppb.

Results
$
The
chronic
dietary
risk
(
food
+
water)
of
napropamide
is
well
below
the
Agency's
level
of
concern
(
i.
e.,
less
than
100%
of
the
aPAD
is
utilized)
for
the
general
U.
S.
population
and
all
population
subgroups.
The
most
highly
exposed
subgroup
was
children,
1­
2
years
old
at
1.8%
of
the
cPAD.
Note
that
this
analysis
reflects
conservative
and
unrefined
Tier
1
estimates.

Cancer
Risk
Napropamide
has
been
classified
a
Group
"
E"
carcinogen
(
no
evidence
of
carcinogenicity).
Therefore,
a
cancer
assessment
was
not
conducted.

Residential
Risk
Napropamide
is
registered
for
use
in
the
residential
setting
to
kill
weeds
on
lawns.
Residents
may
be
exposed
to
napropamide
through
handling
the
pesticide,
or
by
entering
a
treated
site
after
a
residential
or
commercial
applicator
has
applied
napropamide.
It
is
formulated
for
residential
use
as
a
granular
product.

Residential
risk
is
measured
by
a
Margin
of
Exposure
(
MOE),
which
measures
how
close
the
residential
exposure
comes
to
the
NOAEL
from
animal
studies.
Generally,
MOEs
that
are
greater
than
100
do
not
exceed
the
Agency's
level
of
concern
(
the
standard
level
of
concern
MOE
incorporates
the
standard
uncertainty
factors
of
10x
for
interspecies
variability
and
10x
for
intraspecies
variability).

The
toxicological
endpoints
used
for
the
residential
risk
assessment
are
provided
in
Table
2.
No
short
­
or
intermediate­
term
dermal
exposures
or
risks
were
assessed
for
napropamide,
since
no
dermal
toxicological
endpoints
of
concerns
were
identified.
EPA
did
assess
short­
and
intermediate­
term
inhalation
exposures
and
risks
to
residential
handlers.
Since
the
residential
handler
exposure
scenarios
for
napropamide
are
only
considered
to
be
short­
term
in
nature
due
to
the
episodic
use
patterns,
EPA
does
not
anticipate
long­
term
exposures.
Therefore,
no
long­
term
dermal
or
inhalation
exposures
or
risks
were
assessed.
6
Table
2.
Napropamide
Toxicological
Endpoints
Used
for
Occupational
&
Residential
Risk
Assessment
Exposure
Scenario
Dose
Used
in
Risk
Assessment
Study
and
Toxicological
Effects
Incidental
Oral
Short­
Term
(
1­
30
days)
&
Incidental
Oral
Intermediate
(
1­
6
month)
NOAEL
=
30
mg/
kg/
day
UF
=
100x
FQPA
Safety
Factor
=
1x
Reproductive
Toxicity
­
Rat
LOAEL
=
100
mg/
kg/
day
based
on
decreased
pup
body
weight
MRID
No.
92125069
Inhalation
Short­
Term
(
1­
30
days)
&
Inhalation
Intermediate­
Term
(
1­
6
months)
Oral
Study
NOAEL
=
30
mg/
kg/
day
(
Inhalation
absorption
rate=
100%)
UF
=
100x
FQPA
Safety
Factor
=
1x
Reproductive
Toxicity
­
Rat
LOAEL
=
100
mg/
kg/
day
based
on
decreased
pup
body
weight
MRID
No.
92125069
Cancer
(
oral,
dermal,
inhalation)
Classification:
No
evidence
of
Carcinogenicity
Homeowner
Applications
to
Lawns
°
The
MOEs
for
residential
handler
inhalation
exposure
were
calculated
for
four
residential
exposure
scenarios
using
standard
assumptions,
maximum
label
rates,
and
unit
exposure
data
from
either
the
Pesticide
Handlers
Exposure
Database
(
PHED)
or
the
Outdoor
Residential
Exposure
Task
Force
(
ORETF).
The
estimated
risks
for
all
scenarios
do
not
exceed
the
Agency's
level
of
concern
for
inhalation
risk
assessments.
The
MOEs
ranged
from
28,000
to
190,000.

Residential
Turf
Post­
Application
Scenario
°
Residential
post­
application
exposure
to
napropamide
on
treated
lawns
was
assessed
for
toddlers
and
adults.
The
MOEs
for
residential
turf
exposures
were
calculated
using
Turf
Transferable
Residue
data,
maximum
label
rates
and
EPA's
Residential
Standard
Operating
Procedure.
Risks
were
calculated
for
incidental
oral,
hand­
to­
mouth,
object
to
mouth
and
soil
ingestion
pathways.
The
short
term
total
MOE
is
265,
and
is,
therefore,
below
EPA's
level
of
concern.

Aggregate
Risk
Short­
and
long
term
(
chronic)
aggregate
risks
assessments
were
conducted
for
napropamide.
The
short­
term
assessment
considered
both
dietary
(
food
+
water)
and
residential
exposures.
The
long­
term
assessment
considered
dietary
exposure
only,
since
the
current
uses
of
napropamide
are
not
expected
to
result
in
long­
term
residential
exposure.
7
Short­
Term
Aggregate
Risk
Short­
term
aggregate
exposure
takes
into
account
residential
exposure
plus
average
exposure
levels
from
residues
of
napropamide
in
food
and
water.
The
MOE
level
of
concern
for
short­
term
aggregate
risk
is
100.
Since
the
estimated
short­
term
aggregate
risk
MOEs
for
adults
and
children
(
toddlers)
are
14,340
and
260,
respectively,
short­
term
aggregate
risk
is
below
EPA's
level
of
concern
for
napropamide.

Long­
Term
Aggregate
Risk
The
chronic
aggregate
risk
assessment
considered
exposures
from
food
and
water
only
because
there
are
no
residential
uses
expected
to
result
in
chronic
exposures
for
this
chemical.
The
chronic
aggregate
risk
estimates
for
the
U.
S.
population
and
all
subgroups
are
<
2%
of
the
cPAD
and,
therefore,
below
the
Agency's
level
of
concern.

Occupational
Risk
Workers
can
be
exposed
to
a
pesticide
through
mixing,
loading,
applying,
flagging,
and
otherwise
handling
a
pesticide
as
well
as
reentering
previously
treated
sites.
Worker
risk
is
expressed
as
a
Margin
of
Exposure
(
MOE)
which
determines
how
close
the
occupational
exposure
comes
to
a
NOAEL,
which
is
the
highest
dose
given
in
studies
at
which
no
significant
toxic
effects
were
observed.
For
napropamide,
MOEs
less
than
100
exceed
the
Agency's
level
of
concern
for
risk
for
short
and
intermediate
term
occupational
inhalation
exposure
(
1­
30
days
and
30
days
to
several
months,
respectively).

Short­
Term
and
Intermediate­
Term
Handler
Risks
$
Napropamide
use
patterns
show
that
both
short­
term
and
intermediate
term
exposure
to
handlers
is
possible.

$
No
short­
or
intermediate
dermal
endpoint
of
concern
was
identified
for
napropamide,
and
no
long­
term
handler
exposure
is
expected
based
on
the
current
use
patterns.
Therefore,
only
short­
and
intermediate­
term
inhalation
exposures
were
assessed.

$
The
short­
term
and
intermediate­
term
inhalation
NOAEL
is
30
mg/
kg/
day
and
is
based
on
decreased
pup
weight
seen
in
a
reproductive
toxicity
study
in
rats
(
MRID
No.
92125069).
An
oral
endpoint
was
chosen
because
of
a
lack
of
inhalation
toxicity
studies.
An
absorption
factor
of
100%
is
assumed
for
exposure
via
the
inhalation
route.

$
No
chemical­
specific
handler
data
were
submitted,
so
short­
term
and
intermediate­
term
dermal
and
inhalation
exposures
for
handlers
were
developed
using
the
Pesticide
Handler
Exposure
Database
(
PHED)
Version
1.1.
8
$
Estimated
occupational
handler
exposures
for
all
scenarios
do
not
exceed
the
Agency's
level
of
concern
(
i.
e.,
MOEs
>
100).
Short­
and
intermediate
­
term
inhalation
MOEs
range
from
200
to
more
than
33,000.

Post­
Application
Risk
EPA
did
not
assess
occupational
postapplication
risks
to
agricultural
workers
following
treatments
to
agricultural
crops
with
napropamide,
since
no
dermal
endpoint
of
concern
was
identified
and
because
post
application
inhalation
exposure
is
expected
to
be
negligible
since
sprays
and
dusts
have
settled.

Ecological
Risk
Assessment
To
estimate
potential
ecological
risks,
EPA
integrates
the
results
of
exposure
and
ecotoxicity
studies
using
the
quotient
method.
Risk
quotients
(
RQs)
are
calculated
by
dividing
estimated
environmental
concentrations
(
EECs)
of
the
pesticide
by
acute
and
chronic
toxicity
values.
EECs
are
generally
based
on
the
maximum
application
rates
for
that
pesticide.

Risk
quotients
are
then
compared
to
the
Agency's
level
of
concern
(
LOCs).
These
LOCs
are
used
to
analyze
potential
risk
to
non­
target
organisms
and
to
determine
the
need
for
regulatory
action.
Risk
characterization
provides
further
information
on
the
likelihood
of
adverse
effects
occurring
by
considering
the
fate
of
the
chemical
in
the
environment,
communities
and
species
potentially
at
risk,
their
spatial
and
temporal
distributions,
and
the
nature
of
the
effects
observed
in
studies.
If
the
RQ
is
higher
than
the
LOC,
the
Agency
may
have
a
concern.

Environmental
Fate
and
Transport
$
Napropamide
may
be
persistent
in
the
terrestrial
environment
resulting
in
the
potential
for
napropamide
to
reach
the
aquatic
environment
by
runoff.

$
Based
on
laboratory
studies,
the
half
life
for
napropamide
is
approximately
446
days,
therefore
there
is
the
potential
for
the
chemical
to
accumulate
in
the
soil
with
repeated
applications.
However,
field
dissipation
studies
(
where
napropamide
was
soil
incorporated),
indicate
much
faster
dissipation
rates
on
the
order
of
17
to
24
days.

$
Napropamide
can
photodegrade
in
water,
however,
this
route
of
dissipation
is
expected
to
be
impeded
when
soil
incorporation
occurs
at
the
time
of
application.
In
addition,
any
napropamide
that
reaches
surface
water
will
tend
to
partition
to
suspended
soils
and
sediment,
thereby
reducing
the
amount
available
to
undergo
photolysis.

$
Napropamide
is
not
expected
to
be
a
bioaccumulative
compound
of
concern
because
it
is
water
soluble
and
is
rapidly
metabolized.
The
major
terminal
degradate
in
terrestrial
9
environments
is
carbon
dioxide,
but
photodegradation
in
aquatic
systems
creates
isomers
of
the
parent
compound.

Nontarget
Terrestrial
Animal
Risk
$
For
avian
risks,
no
acute
or
chronic
LOCs
were
exceeded.

$
Acute
risks
were
below
the
Agency's
level
of
concern
for
mammals.

$
Chronic
LOCs,
based
on
reduced
parental
and
offspring
body
weight,
were
exceeded
for
mammals
on
all
food
types
(
i.
e.,
short
grass,
tall
grass,
broadleaf
plants
and
small
insects,
fruits/
pods/
large
insects)
for
all
modeled
use
rates.
RQ
estimates
ranged
from
1
to
60
(
LOC=
1).

Nontarget
Terrestrial
Plants
°
For
spray
chemigation,
listed
terrestrial
and
wetland/
riparian
plant
(
monocot
and
dicot)
LOCs
for
seedling
emergence
in
areas
adjacent
to
treated
fields
were
exceeded
at
all
application
rates
evaluated.
RQ
estimates
ranged
from
1
to
348.

Nontarget
Aquatic
Animal
Risk
$
Acute
risks
for
non­
endangered
freshwater
or
marine/
estuarine
fish
and
invertebrates
were
below
the
Agency's
level
of
concern
for
all
uses.

$
Chronic
risks
to
aquatic
organisms
could
not
be
evaluated
because
there
were
no
chronic
data
submitted.
These
data
were
not
required,
however,
the
Agency
has
determined
that
chronic
toxicity
data
should
be
submitted
because
of
the
potential
environmental
persistence
of
napropamide
which
may
cause
chronic
exposure
to
aquatic
organisms.
Therefore,
chronic
risks
cannot
be
precluded.

Nontarget
Aquatic
Plant
Risk
°
Based
on
a
single
green
algae
toxicity
study,
risks
for
aquatic
plants
were
not
above
the
Agency's
level
of
concern.
Because
data
were
not
submitted
for
several
algal
and
aquatic
plant
species,
the
potential
for
adverse
effects
of
napropamide
exposure
to
aquatic
plants
and
algae
could
not
be
fully
assessed.

Risk
to
Endangered
Species
°
The
preliminary
risk
assessment
for
endangered
species
indicates
that
RQs
exceed
the
Agency's
level
of
concern
for:
freshwater
mollusks
(
LOC
=
0.05)
following
application
to
Florida
citrus
and
Georgia
pecans;
mammals
(
LOC
=
0.1)
on
all
modeled
use
rates;
and
10
terrestrial
monocot
and
dicot
plants
(
LOC=
1.0)
living
in
both
wetlands
and
adjacent
areas.
RQs
run
as
high
as
0.09
for
freshwater
mollusks,
60
for
mammals,
and
348
for
plants.
These
findings
are
based
solely
on
EPA's
screening
level
assessment
and
do
not
constitute
"
may
affect"
finding
under
the
Endangered
Species
Act.

Summary
of
Pending
Data
Residue
Chemistry
Deficiencies
860.1340
Residue
Analytical
Method
­
Plants.

860.1500
Crop
Field
Trials
are
required
for
the
following
commodities:
citrus
fruits,
pome
fruits,
stone
fruits,
berries,
and
tree
nuts
as
well
as
on
the
individual
crops
of
avocado,
cranberry,
fig,
grape,
kiwifruit,
olives,
persimmon,
and
strawberry.

860.1520
Magnitude
of
Residue
in
Processed
Food/
Feed
(
Coffee).

Product
Chemistry
Deficiencies
830.1550
Product
Identity
and
Disclosure
of
Ingredients
(
composition
and
chemical
identity)

830.1600
Starting
Materials
&
Manufacturing
Process
(
Description
of
Beginning
Materials
Used
to
Produce
the
Product)

830.1620
Description
of
the
Production
Process
830.1700
Preliminary
Analysis
830.1750
Certified
Limits
(
Certification
of
Limits)

830.1800
Enforcement
Analytical
Method
(
Analytical
methods
to
verify
certified
limits)

830.6313
Stability
to
Normal
and
Elevated
Temperatures,
Metals
and
Metal
Ions
(
stability)

830.7050
Ultraviolet/
Visible
Absorption
Environmental
Toxicity
850.1300
Daphnid
Chronic
Toxicity
Test
(
early
life
stage
in
fish)
11
850.1350
Mysid
(
Shrimp)
Chronic
Toxicity
Test
(
life
cycle
in
aquatic
invertebrates)

850.1500
Fish
Life
Cycle
Study
850.4400
Aquatic
Plant
Toxicity
Test
Using
the
Following
Species:
Lemna
gibba,
Skeletonema
costatum,
Anabaena
flos­
aquae,
and
a
freshwater
diatom
such
as
Navicula
pelliculosa.
