1
September
30,
2004
MEMORANDUM
SUBJECT:
Zinc
Pyrithione
Ecological
Hazard
and
Environmental
Risk
Characterization
Chapter
for
the
Reregistration
Eligibility
Decision
(
RED)
Document
(
D309561)

FROM:
Kathryn
Montague,
M.
S.,
Biologist
Risk
Assessment
and
Science
Support
Branch
Antimicrobials
Division
(
7510C)

THRU:
Rick
Petrie,
Team
Leader
Norm
Cook,
Branch
Chief
Risk
Assessment
and
Science
Support
Branch
Antimicrobials
Division
(
7510C)

Attached
is
the
Zinc
Pyrithione
ecological
hazard
and
environmental
risk
characterization
for
incorporation
into
the
RED
document.
This
has
been
revised
from
the
April,
2004,
version,
per
error
correction
and
public
comments.
2
ZINC
Pyrithione
(
Zinc
2­
pyridinethiol­
1­
oxide)(
088002)

Ecological
Hazard
Assessment
and
Environmental
Risk
Characterization
Executive
Summary:

Zinc
pyrithione
is
a
bacteriostat,
fungicide,
microbiocide/
microbiostat
registered
for
preservative
uses
in
food
packaging
adhesives,
food
packaging
materials,
conveyor
belts,
and
repeat
use
polymeric
food
contact
materials
(
indoor
food),
control
of
bacterial
growth
on
laundered
products
(
indoor
nonfood),
preservation
of
adhesives,
caulks,
patching
compounds,
sealants,
grouts,
latex
paints,
coatings,
dry
wall,
gypsum,
pearlite,
plaster
(
indoor
nonfood),
and
ductwork
(
HVAC
use).
Zinc
pyrithione
is
also
used
for
the
control
of
mildew
in
nonfood
contact
polymers
and
control
of
mildew
and
bacteria
in
styrene
butadiene
rubber
and
thermoplastic
resins
(
e.
g.
air
ducts).
Materials
preservation
extends
to
in­
can
preservation
of
clay,
mineral,
pigment
and
guar
gum
slurries,
latex
emulsions,
and
similar
high
solids
aqueous
media.
Zinc
pyrithione
is
also
conditionally
registered
as
an
antifoulant
for
incorporation
as
an
active
ingredient
into
boat
paints.

The
ecological
effects
database
for
zinc
pyrithione
is
adequate
to
support
the
indoor
uses
considered
in
this
RED.
Zinc
pyrithione
is
moderately
toxic
to
birds
via
acute
oral
exposure,
and
slightly
toxic
to
practically
non­
toxic
to
birds
via
dietary
exposure.
It
is
also
acutely
toxic
to
mammals
via
oral
ingestion
(
Toxicity
Category
II).
Zinc
pyrithione
is
very
highly
toxic
on
an
acute
basis
to
freshwater
and
marine
fish
and
invertebrates,
as
well
as
to
aquatic
plant
species.
It
also
causes
adverse
impacts
on
freshwater
and
marine
invertebrate
reproduction
and
growth
at
very
low
levels.

Due
to
the
high
toxicity
of
the
parent
compound
to
aquatic
organisms,
coupled
with
the
parent
compound's
tendency
to
break
down
fairly
rapidly
into
more
persistent
degradates
in
aquatic
systems,
aquatic
organism
acute
toxicity
tests
with
two
major
degradates
of
zinc
pyrithione
were
submitted.
These
data
indicate
that
both
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid
are
only
slightly
toxic
to
practically
non­
toxic
to
freshwater
and
marine/
estuarine
fish
and
invertebrates
and
aquatic
plants.

Zinc
pyrithione
caused
impacts
on
growth
and
reproduction
to
several
species
of
aquatic
organisms
in
laboratory
studies,
at
levels
slightly
below
the
LC
50.
These
types
of
effects
suggest
that
zinc
pyrithione
is
a
potential
endocrine
disruptor.
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
3
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
effects
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).
Appropriate
endocrine
disruption
screening
and/
or
testing
protocols
have
not
yet
been
validated.
When
such
tests
have
been
validated,
Arch
will
evaluate
zinc
pyrithione
in
such
assays
(
G.
Schiffliti,
pers.
comm.).

Environmental
exposure
modeling
was
not
conducted
for
the
indoor
uses
of
zinc
pyrithione
considered
in
this
RED.
Exposure
to
terrestrial
and
aquatic
organisms
and
plants
is
expected
to
be
minimal
from
these
indoor
uses.
Therefore,
a
full
ecological
risk
assessment
was
not
conducted
for
this
RED.
Risk
to
birds,
mammals,
fish,
aquatic
invertebrates,
and
plants,
including
Endangered
species,
is
not
anticipated
from
the
indoor
uses
of
zinc
pyrithione.
The
ecological
risks
from
the
time­
limited
antifoulant
paint
use
will
be
evaluated
later,
following
a
review
of
the
recently
submitted
ecotoxicity
studies.

An
environmental
risk
assessment
for
antifouling
paints
was
not
included
in
the
reregistration
eligibility
decision
document.
AD
has
recently
received
5
new
studies
conducted
by
Arch
in
support
of
zinc
pyrithione
registration
as
an
antifoulant,
and
these
studies
are
currently
in
review.
Once
the
data
have
been
reviewed
and
found
acceptable,
a
reassessment
of
the
environmental
risks
associated
with
the
antifouling
paint
uses
of
zinc
pyritione
will
be
conducted,
and
will
include
revised
environmental
modeling
as
well
as
endpoints
from
the
recently
conducted
studies.

I.
Toxicity
to
Terrestrial
Animals
A.
Birds,
Acute
and
Subacute
1.
Zinc
Pyrithione
parent
compound
An
acute
oral
toxicity
study
using
the
technical
grade
of
the
active
ingredient
is
required
to
establish
the
toxicity
of
a
pesticide
to
birds.
The
preferred
test
species
is
either
mallard
duck
or
bobwhite
quail.
Results
of
this
test
are
tabulated
below.

Table
1.
Avian
Acute
Oral
Toxicity
of
Zinc
Pyrithione
Species
%
a.
i.
LD50
(
mg/
kg)
95
%
c.
i.
NOAEL
Toxicity
category
MRID
No.
Author/
Yea
r
Study
Classificatio
n
4
Northern
bobwhite
(
Colinus
virginianus)
96
60
(
44
­
81)
<
31.2
moderately
toxic
43864611
Campbell/
1993
Core
These
results
indicate
that
zinc
pyrithione
is
moderately
to
avian
species
on
an
acute
oral
basis.
The
guideline
requirement
(
71­
1/
OPPTS
850.2100)
is
fulfilled
(
MRID#
43864611).

Two
subacute
dietary
studies
using
the
technical
grade
of
the
active
ingredient
are
required
to
establish
the
toxicity
of
a
pesticide
to
birds.
The
preferred
test
species
are
mallard
duck
(
a
waterfowl)
and
bobwhite
quail
(
an
upland
gamebird).
Results
of
avian
subacute
dietary
tests
are
tabulated
below.

Table
2.
Avian
Subacute
Dietary
Toxicity
of
Zinc
Pyrithione
Species
%
ai
LC50
(
ppm)
(
95
%
c.
i.)
NOAEC
(
ppm)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Northern
Bobwhite
(
Colinus
virginianus)
96
1063
(
789
­
1412)
<
253
slightly
toxic
43864610
Campbell/
1994
core
Mallard
(
Anas
platyrhynchos)
96
>
5000
(
N/
A)
<
275
practicall
y
nontoxic
43864612
Campbell/
1994
core
These
results
indicate
that
zinc
pyrithione
is
slightly
toxic
to
practically
non­
toxic
to
avian
species
on
a
subacute
dietary
basis.
The
guideline
requirement
(
71­
2/
OPPTS
850.2200)
is
fulfilled
(
MRID
#
43864610,
43864612).

B.
Birds,
Chronic
Avian
reproduction
studies
using
the
technical
grade
of
the
active
ingredient
are
required
for
a
pesticide
when
any
of
the
following
conditions
are
met:
(
1)
birds
may
be
subject
to
repeated
or
continuous
exposure
to
the
pesticide,
especially
preceding
or
during
the
breeding
season,
(
2)
the
pesticide
is
stable
in
the
environment
to
the
extent
that
potentially
toxic
amounts
may
persist
in
animal
feed,
(
3)
the
pesticide
is
stored
or
accumulated
in
plant
or
animal
tissues,
and/
or,
(
4)
information
derived
from
mammalian
reproduction
studies
indicates
reproduction
in
terrestrial
vertebrates
may
be
adversely
affected
by
the
anticipated
use
of
the
product.
The
currently
registered
uses
of
zinc
pyrithione
do
not
require
avian
reproduction
testing.
No
avian
reproduction
data
is
available
for
zinc
pyrithione.

C.
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
5
characteristics.
In
most
cases,
rat
or
mouse
toxicity
values
obtained
from
studies
conducted
to
support
data
requirements
for
human
health
risk
assessment
substitute
for
wild
mammal
testing.
These
toxicity
values
are
reported
in
the
table
below.

Table
3
.
Mammalian
Acute
Toxicity
of
Zinc
Pyrithione
Species
%
ai
Test
Type
Toxicity
Values
(
mg/
kg)/
category
MRID
No.
Author/
year
Laboratory
rat
(
Rattus
norvegicus)
tech
acute
oral
LD50
630(
m),
460
(
f)
/
II
42827901
Moreno/
1986
Mammalian
chronic
toxicity
studies
were
not
available
for
zinc
pyrithione.

D.
Insects
A
honey
bee
acute
contact
study
using
the
technical
grade
of
the
active
ingredient
is
not
required
for
the
currently
registered
uses
of
zinc
pyrithione.

E.
Terrestrial
Field
Testing
Terrestrial
field
testing
is
not
required
for
the
currently
registered
uses
of
zinc
pyrithione.

II.
Toxicity
to
Freshwater
Aquatic
Animals
A.
Freshwater
Fish,
Acute
1.
Parent
compound
Two
freshwater
fish
toxicity
studies
using
the
technical
grade
of
the
active
ingredient
are
required
to
establish
the
toxicity
of
a
pesticide
to
fish.
The
preferred
test
species
are
rainbow
trout
(
a
coldwater
fish)
and
bluegill
sunfish
(
a
warmwater
fish).
Results
of
these
tests
are
tabulated
below.

Table
4
.
Freshwater
Fish
Acute
Toxicity
of
Zinc
Pyrithione
Species
%
ai
LC50
(
ppb
ai)
(
95
%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Rainbow
trout
(
Oncorhynchus
mykiss)
97.8
3.6
(
3.07
­
4.33)
1.6
very
highly
toxic
43864613
Boeri/
1994
core
Table
4
.
Freshwater
Fish
Acute
Toxicity
of
Zinc
Pyrithione
Species
%
ai
LC50
(
ppb
ai)
(
95
%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
6
Fathead
minnow
(
Pimephales
promelas)
97.8
2.68
(
2.10
­
3.27)
1.1
very
highly
toxic
43864606
Boeri/
1994
core
These
results
indicate
that
zinc
pyrithione
is
very
highly
toxic
to
freshwater
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
1/
OPPTS
850.1075)
is
fulfilled
(
MRID#
43864613,
43864606).

2.
Degradates
Zinc
pyrithione
has
two
major
degradates,
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid.
Two
freshwater
fish
acute
toxicity
studies
using
these
degradates
were
submitted.

Table
5.
Freshwater
Fish
Acute
Toxicity
of
Pyridine
sulfonic
acid
(
zinc
pyrithione
degradate).

Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Rainbow
trout
(
Oncorhynchus
mykiss)
98
57100
(
48300
­
69800)
46900
slightly
toxic
43864627
Ward/
1993
core
Fathead
minnow
(
Pimephales
promelas)
98
68500
(
55200
­
85000)
55200
slightly
toxic
43864621
Boeri/
1994
core
These
results
indicate
that
pyridine
sulfonic
acid
is
slightly
toxic
to
freshwater
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
1/
OPPTS
850.1075)
is
fulfilled
(
MRID#
43864627,
43864621).

Table
6
.
Freshwater
Fish
Acute
Toxicity
of
Pyrithione
sulfonic
acid
(
zinc
pyrithione
degradate).

Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Rainbow
trout
(
Oncorhynchus
mykiss)
98.5
92300
(
73600
­
124000)
73600
slightly
toxic
43864616
Ward/
1994
core
Table
6
.
Freshwater
Fish
Acute
Toxicity
of
Pyrithione
sulfonic
acid
(
zinc
pyrithione
degradate).

Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
7
Fathead
minnow
(
Pimephales
promelas)
98.5
58800
(
48700
­
71000)
48700
slightly
toxic
43864618
Ward/
1994
core
These
results
indicate
that
pyrithione
sulfonic
acid
is
slightly
toxic
to
freshwater
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
1/
OPPTS
850.1075)
is
fulfilled
(
MRID#
43864616,
43864618).

B.
Freshwater
Fish,
Chronic
A
freshwater
fish
early
life­
stage
test
using
the
technical
grade
of
the
active
ingredient
is
required
for
a
pesticide
when
it
may
be
applied
directly
to
water
or
if
the
end­
use
product
is
expected
to
be
transported
to
water
from
the
intended
use
site,
and
any
of
the
following
conditions
are
met:
(
1)
the
pesticide
is
intended
for
use
such
that
its
presence
in
water
is
likely
to
be
continuous
or
recurrent
regardless
of
toxicity,
(
2)
any
aquatic
acute
LC50
or
EC50
is
less
than
1
mg/
l,
(
3)
the
EEC
in
water
is
equal
to
or
greater
than
0.01
of
any
acute
LC50
or
EC50
value,
or,
(
4)
the
actual
or
estimated
environmental
concentration
in
water
resulting
from
use
is
less
than
0.01
of
any
acute
LC50
or
EC50
value
and
any
one
of
the
following
conditions
exist:
studies
of
other
organisms
indicate
the
reproductive
physiology
of
fish
may
be
affected,
physicochemical
properties
indicate
cumulative
effects,
or
the
pesticide
is
persistent
in
water
(
e.
g.,
half­
life
greater
than
4
days).
The
preferred
test
species
is
rainbow
trout,
but
other
species
may
be
used..
Freshwater
fish
early
life­
stage
testing
is
required
for
zinc
omadine
and
its
major
degradates
due
to
the
very
high
acute
toxicity
of
parent
zinc
omadine
to
freshwater
fish.
The
results
of
this
testing
is
summarized
below:

Table
7.
Freshwater
Fish
Early
Life­
Stage
Toxicity
of
Zinc
Omadine
®
(
parent)

Species
%
ai
NOAEC/
LOAEC
(
ppb)
Endpoints
Affected
MRID
No.
Author/
Year
Study
Classification
Fathead
minnow
(
Pimephales
promelas)
98.2
1.22/
2.82
Survival,
sublethal
effects
(
bent
spinal
columns),
and
length
45204102
Boeri/
1999
core
The
guideline
requirement
(
72­
4b/
OPPTS
850.1300)
is
fulfilled
(
MRID#
44535401).
8
Table
8.
Freshwater
Fish
Early
Life­
Stage
Toxicity
of
Pyridine­
2­
sulfonic
acid
Species
%
ai
NOAEC/
LOAEC
(
ppb)
Endpoints
Affected
MRID
No.
Author/
Year
Study
Classification
Fathead
minnow
(
Pimephales
promelas)
98.2
NOAEC
=
10
(
highest
level
tested)
no
adverse
effects
observed
45204102
Boeri/
1999
core
The
guideline
requirement
(
72­
4b/
OPPTS
850.1300)
is
fulfilled.

C.
Freshwater
Invertebrates,
Acute
1.
Parent
compound
A
freshwater
aquatic
invertebrate
toxicity
test
using
the
technical
grade
of
the
active
ingredient
is
required
to
establish
the
toxicity
of
a
pesticide
to
invertebrates.
The
preferred
test
species
is
Daphnia
magna.
Results
of
this
test
are
tabulated
below.

Table
8
.
Freshwater
Invertebrate
Acute
Toxicity
of
Zinc
Pyrithione
(
parent)

Species
%
ai
LC50
or
EC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Waterflea
(
Daphnia
magna)
97.8
8.25
(
5.24
­
25.82)
<
1.1
very
highly
toxic
43864604
Boeri/
1994
core
Freshwater
amphipod,
Hyalella
azteca
98.2
136
ppb
highly
toxic
449218­
01
Supplemental
The
results
indicate
that
parent
zinc
pyrithione
is
highly
to
very
highly
toxic
to
aquatic
invertebrates
on
an
acute
basis.
The
guideline
requirement
(
72­
2/
OPPTS
850.1010)
is
fulfilled
(
MRID#
43864604).

2.
Degradates
Zinc
pyrithione
has
two
major
degradates,
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid.
Two
freshwater
invertebrate
acute
toxicity
studies
using
these
degradates
were
submitted.
9
Table
9
.
Freshwater
Invertebrate
Toxicity
of
Pyridine
Sulfonic
Acid
Species
%
ai
LC50
or
EC50
(
ppb
ai)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Waterflea
(
Daphnia
magna)
98
>
122000
122000
practically
non
toxic
43864622
Ward/
1994
core
The
results
indicate
that
pyridine
sulfonic
acid
is
practically
non­
toxic
to
aquatic
invertebrates
on
an
acute
basis.
The
guideline
requirement
(
72­
2/
OPPTS
850.1010)
is
fulfilled
(
MRID#
43864622)
for
this
degradate
of
zinc
pyrithione.

Table
10
.
Freshwater
Invertebrate
Toxicity
of
Pyrithione
Sulfonic
Acid
Species
%
ai
LC50
or
EC50
(
ppb
ai)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Waterflea
(
Daphnia
magna)
98.5
>
127000
32800
practically
non­
toxic
43864619
Ward/
1994
core
The
results
indicate
that
pyrithione
sulfonic
acid
is
practically
non­
toxic
to
aquatic
invertebrates
on
an
acute
basis.
The
guideline
requirement
(
72­
2/
OPPTS
850.1010)
is
fulfilled
(
MRID#
43864619)
for
this
degradate
of
zinc
pyrithione.

D.
Freshwater
Invertebrate,
Chronic
A
freshwater
aquatic
invertebrate
life­
cycle
test
using
the
technical
grade
of
the
active
ingredient
is
required
for
a
pesticide
if
the
end­
use
product
may
be
applied
directly
to
water
or
expected
to
be
transported
to
water
from
the
intended
use
site,
and
any
of
the
following
conditions
are
met:
(
1)
the
pesticide
is
intended
for
use
such
that
its
presence
in
water
is
likely
to
be
continuous
or
recurrent
regardless
of
toxicity,
(
2)
any
aquatic
acute
LC50
or
EC50
is
less
than
1
mg/
l,
or,
(
3)
the
EEC
in
water
is
equal
to
or
greater
than
0.01
of
any
acute
EC50
or
LC50
value,
or,
(
4)
the
actual
or
estimated
environmental
concentration
in
water
resulting
from
use
is
less
than
0.01
of
any
aquatic
acute
EC50
or
LC50
value
and
any
of
the
following
conditions
exist:
studies
of
other
organisms
indicate
the
reproductive
physiology
of
invertebrates
may
be
affected,
physicochemical
properties
indicate
cumulative
effects,
or
the
pesticide
is
persistent
in
water
(
e.
g.,
half­
life
greater
than
4
days).
The
preferred
test
species
is
Daphnia
magna.
Freshwater
aquatic
invertebrate
lifecycle
testing
was
required
for
zinc
pyrithione
due
to
the
likelihood
of
runoff
from
the
application
sites,
the
likelihood
of
repeated
or
continuous
exposure
from
multiple
applications,
and
the
high
acute
toxicity
to
freshwater
invertebrates.
Results
of
this
test
are
tabulated
below.
10
Table
11.
Freshwater
Aquatic
Invertebrate
Life­
Cycle
Toxicity
of
Zinc
Pyrithione
Species
%
ai
NOAEC/
LOAEC
(
ppb)
Endpoints
Affected
MRID
No.
Author/
Year
Study
Classification
Waterflea
(
Daphnia
magna)
98.2
2.7/
5.8
reproduction
length
44535401
Boeri/
1998
core
The
guideline
requirement
(
72­
4b/
OPPTS
850.1300)
is
fulfilled
(
MRID#
44535401).

E.
Freshwater
Field
Studies
No
freshwater
field
studies
were
submitted
for
zinc
pyrithione.

III.
Toxicity
to
Estuarine
and
Marine
Animals
A.
Estuarine
and
Marine
Fish,
Acute
1.
Parent
Acute
toxicity
testing
with
estuarine/
marine
fish
using
the
technical
grade
of
the
active
ingredient
is
required
for
a
chemical
when
the
end­
use
product
is
intended
for
direct
application
to
the
marine/
estuarine
environment
or
the
active
ingredient
is
expected
to
reach
this
environment
because
of
its
use
in
coastal
counties.
The
preferred
test
species
is
sheepshead
minnow.

Table
12
.
Acute
Toxicity
of
Zinc
Pyrithione
(
parent)
to
Estuarine/
Marine
Fish
Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Sheepshead
minnow
(
Cyprinodon
variegatus)
97.8
400
(
200­
590)
200
highly
toxic
43864605
Boeri/
1994
core
The
results
indicate
that
parent
zinc
pyrithione
is
highly
toxic
to
estuarine/
marine
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
3a/
OPPTS
850.1025)
is
fulfilled
(
MRID
#
43864605).

2.
Degradates
Zinc
pyrithione
has
two
major
degradates,
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid.
Two
marine/
estuarine
fish
acute
toxicity
studies
using
these
degradates
were
submitted.
11
Table
13.
Acute
Toxicity
of
Pyridine
Sulfonic
Acid
to
Estuarine/
Marine
Fish
Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Sheepshead
minnow
(
Cyprinodon
variegatus)
98
>
127000
127000
practicall
y
nontoxic
43864623
Boeri/
1994
core
The
results
indicate
that
pyridine
sulfonic
acid
is
practically
non­
toxic
to
estuarine/
marine
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
3a/
OPPTS
850.1025)
is
fulfilled
(
MRID
#
43864623).

Table
14.
Acute
Toxicity
of
Pyrithione
Sulfonic
Acid
to
Estuarine/
Marine
Fish
Species
%
ai
LC50
(
ppb
ai)
(
95%
c.
i.)
NOAEC
(
ppb
ai)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Sheepshead
minnow
(
Cyprinodon
variegatus)
98.5
>
137000
137000
practically
non­
toxic
43864617
Boeri/
1994
core
The
results
indicate
that
pyrithione
sulfonic
acid
is
practically
non­
toxic
to
estuarine/
marine
fish
on
an
acute
basis.
The
guideline
requirement
(
72­
3a/
OPPTS
850.1025)
is
fulfilled
(
MRID
#
43864617).

B.
Estuarine
and
Marine
Fish,
Chronic
Estuarine/
marine
fish
early
life­
stage
testing
is
not
required
for
the
currently
registered
uses
of
zinc
pyrithione.
The
freshwater
fish
early
life­
stage
test,
which
is
required,
should
provide
an
adequate
endpoint
for
use
in
future
risk
assessments,
since
freshwater
fish
species
appear
to
be
more
sensitive
to
zinc
pyrithione
than
marine/
estuarine
species.

C.
Estuarine
and
Marine
Invertebrates,
Acute
1.
Parent
Compound
Acute
toxicity
testing
with
estuarine/
marine
invertebrates
using
the
technical
grade
of
the
active
ingredient
is
required
for
a
pesticide
when
the
end­
use
product
is
intended
for
direct
application
to
the
marine/
estuarine
environment
or
the
active
ingredient
is
expected
to
reach
this
environment
because
of
its
use
in
coastal
counties.
The
preferred
test
species
are
mysid
shrimp
and
eastern
oyster.
Results
of
these
tests
are
tabulated
below.
12
Table
15:
Acute
Toxicity
of
Zinc
Pyrithione
(
parent)
to
Estuarine/
Marine
Invertebrates
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOAEC
(
ppb)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Eastern
oyster
(
Crassostrea
virginica)
shell
deposition
97.8
22.0
(
18.9
­
27.3)
7.1
very
highly
toxic
43864608
Boeri
et
al/
1994
core
Mysid
(
Mysidopsis
bahia)
97.8
4.7
(
4.04­
5.53)
1.6
very
highly
toxic
43864607
Boeri
et
al/
1994
core
The
results
indicate
that
parent
zinc
pyrithione
is
very
highly
toxic
to
estuarine/
marine
invertebrates
on
an
acute
basis.
The
guideline
requirements
(
72­
3b
and
72­
3c/
OPPTS
850.1035
and
850.1045)
are
fulfilled
(
MRID#
43864608,
43864607).

2.
Degradates
Zinc
pyrithione
has
two
major
degradates,
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid.
Two
freshwater
estuarine/
marine
invertebrate
acute
toxicity
studies
using
these
degradates
were
submitted.

Table
16:
Acute
Toxicity
of
Pyridine
Sulfonic
Acid
to
Estuarine/
Marine
Invertebrates
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOAEC
(
ppb)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Eastern
oyster
(
Crassostrea
virginica)
shell
deposition
99.1
85600
(
73300
­
102500)
51100
slightly
toxic
43864624
Boeri
et
al/
1994
core
Mysid
(
Mysidopsis
bahia)
98
71000
(
62800­
81100)
51900
slightly
toxic
43864626
Boeri
et
al/
1994
core
The
results
indicate
that
pyridine
sulfonic
acid
is
slightly
toxic
to
estuarine/
marine
invertebrates
on
an
acute
basis.
The
guideline
requirements
(
72­
3b
and
72­
3c/
OPPTS
850.1035
and
850.1045)
are
fulfilled
for
this
degradate
of
zinc
pyrithione
(
MRID#
43864624,
43864626).
13
Table
17:
Acute
Toxicity
of
Pyrithione
Sulfonic
Acid
to
Estuarine/
Marine
Invertebrates
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOAEC
(
ppb)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Eastern
oyster
(
Crassostrea
virginica)
shell
deposition
98.5
96200
(
89313
­
104560)
21900
slightly
toxic
43864615
Boeri
et
al/
1994
core
Mysid
(
Mysidopsis
bahia)
98.5
70300
(
61600­
81600)
19400
slightly
toxic
43864620
Boeri
et
al/
1994
core
The
results
indicate
that
pyrithione
sulfonic
acid
is
slightly
toxic
to
estuarine/
marine
invertebrates
on
an
acute
basis.
The
guideline
requirements
(
72­
3b
and
72­
3c/
OPPTS
850.1035
and
850.1045)
are
fulfilled
for
this
degradate
of
zinc
pyrithione
(
MRID#
43864615,
43864620).

D.
Estuarine
and
Marine
Invertebrate,
Chronic
An
estuarine/
marine
invertebrate
life­
cycle
toxicity
test
is
required
for
a
pesticide
if
the
end­
use
product
may
be
applied
directly
to
water
or
expected
to
be
transported
to
water
from
the
intended
use
site,
and
any
of
the
following
conditions
are
met:
(
1)
the
pesticide
is
intended
for
use
such
that
its
presence
in
water
is
likely
to
be
continuous
or
recurrent
regardless
of
toxicity,
(
2)
any
aquatic
acute
LC50
or
EC50
is
less
than
1
mg/
l,
or,
(
3)
the
EEC
in
water
is
equal
to
or
greater
than
0.01
of
any
acute
EC50
or
LC50
value,
or,
(
4)
the
actual
or
estimated
environmental
concentration
in
water
resulting
from
use
is
less
than
0.01
of
any
aquatic
acute
EC50
or
LC50
value
and
any
of
the
following
conditions
exist:
studies
of
other
organisms
indicate
the
reproductive
physiology
of
invertebrates
may
be
affected,
physicochemical
properties
indicate
cumulative
effects,
or
the
pesticide
is
persistent
in
water
(
e.
g.,
half­
life
greater
than
4
days).
Estuarine/
marine
invertebrate
life­
cycle
testing
was
submitted
for
zinc
pyrithione.

Table
18:
Chronic
Toxicity
of
Zinc
Pyrithione
(
parent)
to
Estuarine/
Marine
Invertebrates
Species
%
ai.
LOEC
(
ppb)
NOAEC
(
ppb)
MRID
No.
Author/
Year
Study
Classification
Mysid
(
Mysidopsis
bahia)
98.2
growth:
4.20
ppb
repro:
9.16
ppb
growth:
2.28
ppb
repro:
4.20
ppb
44911101
Boeri
et
al/
1999
core
14
E.
Estuarine
and
Marine
Field
Studies
No
estuarine
or
marine
field
study
data
is
available
for
zinc
pyrithione.

IV.
Toxicity
to
Plants
A.
Terrestrial
Currently,
terrestrial
plant
testing
is
not
required
for
pesticides
other
than
herbicides
except
on
a
case­
by­
case
basis
(
e.
g.,
labeling
bears
phytotoxicity
warnings,
incidents
of
plant
damage
have
been
reported,
or
literature
indicating
phytotoxicity
is
available).
Terrestrial
plant
testing
is
not
required
for
zinc
pyrithione.

B.
Aquatic
Aquatic
plant
testing
is
not
required
for
pesticides
other
than
herbicides
except
on
a
case­
by­
case
basis
(
e.
g.,
labeling
bears
phytotoxicity
warnings,
incidents
have
been
reported
involving
plants,
or
literature
is
available
that
indicates
phytotoxicity).
Since
algae
is
a
target
pest
for
zinc
pyrithione,
aquatic
plant
toxicity
testing
was
required.
Tier
II
data
were
submitted
on
the
freshwater
green
alga
Selenastrum
capricornutum
for
parent
zinc
pyrithione
and
the
major
degradates,
pyridine
sulfonic
acid
and
pyrithione
sulfonic
acid.
The
results
of
these
tests
are
tabulated
below.

1.
Parent
Compound
Table
19:
Acute
Toxicity
of
Zinc
Pyrithione
(
parent)
to
Alga
and
Aquatic
Plants
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOEC
(
ppb)
MRID
No.
Author/
Year
Study
Classification
Freshwater
green
alga
(
Selenastrum
capricornutum)
97.8
28.0
(
24.3­
33.0)
7.8
43864609
Ward
et
al/
1994
core
Blue­
green
alga
(
Anabaena
flos­
aquae)
98.3
7.1
3.8
45564901
core
Freshwater
diatom
(
Navicula
pelliculosa)
98.3
2.6
2.4
45565001
core
Aquatic
vascular
plant,
duckweed
(
Lemna
gibba)
98.2
8.87
4.0
45204104
core
The
results
indicate
that
parent
zinc
pyrithione
is
very
highly
toxic
to
aquatic
plants
on
an
acute
15
basis.
Guideline
123­
1/
OPPTS
850.5400
is
not
fulfilled
for
zinc
pyrithione;
testing
on
one
additional
species
(
marine
diatom,
preferably
Skeletonema
costatum)
is
required.

2.
Degradates
Table
20:
Acute
Toxicity
of
Pyridine
Sulfonic
Acid
to
Aquatic
Plants
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOAEC
(
ppb)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Freshwater
green
alga
(
Selenastrum
capricornutum)
98
28900
(
23000
­
46200)
5460
slightly
toxic
43864625
Boeri
et
al/
1994
core
The
results
indicate
that
pyridine
sulfonic
acid
is
slightly
toxic
to
freshwater
green
algae
on
an
acute
basis.
No
further
aquatic
plant
toxicity
testing
with
this
degradate
of
zinc
pyrithione
is
required.

Table
21:
Acute
Toxicity
of
Pyrithione
Sulfonic
Acid
to
Aquatic
Plants
Species
%
ai.
96­
hour
LC50/
EC50
(
ppb)
(
95%
c.
i.)
NOAEC
(
ppb)
Toxicity
Category
MRID
No.
Author/
Year
Study
Classification
Freshwater
green
alga
(
Selenastrum
capricornutum)
98.5
28200
(
26000
­
30800)
11800
slightly
toxic
43864614
Boeri
et
al,
1994
core
The
results
indicate
that
pyrithione
sulfonic
acid
is
slightly
toxic
to
freshwater
green
algae
on
an
acute
basis.
No
further
aquatic
plant
testing
is
required
for
this
degradate
of
zinc
pyrithione.

V.
Environmental
Exposure
and
Risk
Environmental
exposure
modeling
was
not
conducted
for
the
indoor
uses
(
materials
preservative)
of
zinc
pyrithione
considered
in
this
RED.
Exposure
to
terrestrial
and
aquatic
organisms
and
plants
is
expected
to
be
minimal
from
these
indoor
uses.
Therefore,
a
full
ecological
risk
assessment
was
not
conducted
for
this
RED.
Risk
to
birds,
mammals,
fish,
aquatic
invertebrates,
and
plants
is
not
anticipated
from
the
indoor
uses
of
zinc
pyrithione.

An
environmental
risk
assessment
for
antifouling
paints
was
not
included
in
the
reregistration
eligibility
decision
document.
AD
has
recently
received
5
new
studies
conducted
by
Arch
in
support
of
zinc
pyrithione
registration
as
an
antifoulant,
and
these
studies
are
currently
in
review.
16
Once
the
data
have
been
reviewed
and
found
acceptable,
a
reassessment
of
the
environmental
risks
associated
with
the
antifouling
paint
uses
of
zinc
pyritione
will
be
conducted,
and
will
include
revised
environmental
modeling
as
well
as
endpoints
from
the
recently
conducted
studies.

VI.
Endangered
Species
Considerations
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
risk
assessments
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.
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.

Based
on
the
low
likelihood
of
environmental
exposure
from
the
registered
indoor
uses,
adverse
impacts
to
endangered
species
are
not
expected
from
the
registered
uses
of
zinc
pyrithione.
The
ecological
risks
from
the
time­
limited
antifoulant
paint
use
will
be
evaluated
later,
following
a
review
of
the
recently
submitted
ecotoxicity
studies.
