3/
26/
2003
Questions
for
External
Peer
Reviewers
1.
Do
you
perceive
any
significant
problems
with
any
of
the
proposed
protocols
or
test
methods
that
would
jeopardize
evaluation
of
coating
efficacy?

Background:
EPA
recognizes
that
the
performance
of
coatings
on
wood
substrates
is
a
complex
phenomenon,
and
several
pre­
pilot
tests
would
normally
be
employed
to
reveal
flaws
in
the
test
plan
that
may
not
surface
until
well
into
the
study.
This
is
particularly
true
of
the
chamber
accelerated
weathering
tests
where
shrinking
and
swelling
of
the
ends
or
exposed
surfaces
of
the
coupons
may
cause
splitting
and
subsequent
leaching
onto
the
test
surfaces.
Can
the
panel
recommend
specific
test
parameters
(
chamber
temperature,
UV
light
intensity,
precipitation
cycles,
etc.,)
that
would
maximize
the
potential
for
evaluating
the
effects
of
weathering
factors
on
the
coatings
yet
minimize
the
chance
of
unnaturally
damaging
the
coating
or
substrate?

2.
Does
the
selection
criteria
of
the
coating
screening
study
provide
the
correct
coating
candidates
for
the
larger
weathering
study?
If
not,
what
should
be
changed?

Background:
There
is
little
published
data
that
demonstrates
the
initial
level
of
arsenic
reduction
provided
by
a
coating.
The
screening
step
may
or
may
not
provide
insight
into
rank
order
of
the
various
coatings
and/
or
rank
order
of
coating
classes
on
initial
application.
Further,
initial
apparent
efficacy
may
have
little
or
nothing
to
do
with
longer­
term
performance
with
weathering.
In
light
of
these
potential
shortcomings,
does
it
make
sense
for
EPA
to
inform
the
selection
of
coatings
process
with
rank
order
determined
by
the
screening
study?

3.
How
should
EPA
deal
with
coatings
that
require
or
recommend
a
multiple
coating
system
(
e.
g.
primer,
coating)?

Background:
Some
products
recommend
a
multiple
coat
system..
Should
EPA
evaluate
products
that
recommend
multiple
coatings?

4.
Are
the
mini
decks
a
sound
approach
to
evaluation
of
performance
in
the
field?

Background:
In
the
real
world,
playground
structures,
picnic
tables,
decks
etc.,
are
fastened
together
with
nails
and
screws.
The
structure
undergoes
stresses
from
use
as
well
as
weathering
and
these
stresses
may
cause
failure
of
the
coating
system
at
the
joints
and
fastening
points.
What
size
deck
would
the
panel
recommend
to
capture
the
stresses
that
might
be
expected?
5.
How
long
does
the
panel
recommend
that
the
mini
deck
field
trial
last?

Background:
The
accelerated
weathering
chambers
are
expected
to
provide
measurable
performance
separation
between
products
or
classes
of
products.
Does
the
panel
feel
that
the
out­
of­
doors
weathering
experiments
will
provide
useful
information
within
six
months?

6.
Should
EPA
standardize
test
coupon
size
between
the
chamber
and
out­
ofdoors
weathering
experiments?

Background:
Surface
to
volume
and
end
cut
to
length
ratios
may
impact
the
interactions
between
the
coating
and
the
substrate.
EPA
has
chosen
to
use
5/
4
X
6"
decking
in
the
lab
and
field
studies
with
board
lengths
of
about
30
cm
in
the
chambers
and
about
90
cm
in
the
field
tests.
Does
the
panel
feel
that
this
poses
a
serious
risk
to
comparison
of
the
chamber
and
out­
of­
doors
experiments?

7.
Which
is
the
better
approach
to
establish
baseline:
1)
sampling
the
specimens
on
the
surface
to
be
coated
and
subsequently
correcting
for
the
arsenic
removed
before
coating;
or
2)
coat
specimens
whose
surfaces
have
never
been
rubbed
and
establishing
baseline
on
contiguous
specimens?

Background:
The
amount
of
arsenic
measured
by
wipe
sampling
varies
along
the
length
of
a
board
and
from
front
to
back.
The
"
baseline"
concentration
of
arsenic
available
for
contact
at
the
surface
prior
to
coating
can
be
determined
by
wiping
the
surface
prior
to
coating
or
by
wiping
adjacent
surfaces.
Wiping
a
surface
to
be
coated
before
coating
provides
a
direct
measure
of
the
dislodgeable
amount
on
the
surface
prior
to
coating
but
also
removes
that
amount
from
the
surface.
Thus,
if
a
coating
is
applied
over
a
surface
that
has
been
wiped,
one
must
estimate
the
reduction
due
to
"
wiping
effect"
by
sampling
non­
coated,
non­
weathered
boards
a
second
time.
This
approach
to
determination
of
baseline
does
not
consider
that
the
application
process
as
well
as
possible
interactions
between
the
coating
and
the
treated
wood
may
impact
the
residue
level.

8.
EPA
proposes
to
use
deck
boards
of
6"
nominal
width
in
all
the
coatings
evaluations.
The
CPSC
wipe
device
is
3.5"
in
diameter.
This
means
that
the
arsenic
on
each
side
of
the
wipe
will
not
be
removed
by
the
wipe
procedure
at
each
sampling
event.
Can
this
confound
analysis
of
the
data?
Should
EPA
use
coupons
of
the
same
width
as
the
wipe
device
or
modify
the
width
of
the
wipe?

Background:
There
are
two
potential
confounders
related
to
this
question.
First
of
all,
the
wipe
procedure
may
be
considered
a
form
of
abrasion.
The
study
design
does
not
have
a
control
for
this
factor
except
that
the
proposed
mini­
decks
have
one
set
of
boards
that
are
only
wiped
at
the
final
sampling
period.
Secondly,
if
only
a
portion
of
a
board
is
wiped,
contaminants
from
the
non­
wiped
area
may
be
washed
onto
the
wiped
area
by
precipitation
or
condensation
run­
off.
For
the
purposes
of
the
study,
does
it
make
more
sense
to
reduce
the
width
of
the
test
boards
(
at
the
risk
of
exaggerating
surface/
volume
effects),
alter
the
wipe
sampling
device,
or
institute
some
other
control
measure?

9.
How
will
the
decision
to
only
determine
arsenic
concentrations
impact
the
usefulness
of
the
data?

Background:
The
study
design
determines
arsenic
but
not
chromium
or
copper.
The
decision
to
focus
on
arsenic
was
due
to
several
factors:
(
1)
resource
limitations,
(
2)
toxicity
potential
(
most
sensitive
cancer
endpoint)
and
(
3)
potential
confounder
for
chromium.
The
weathering
chambers
are
manufactured
from
aluminum
and
stainless
steel.
Stainless
steel
contains
significant
amounts
of
chromium.
EPA
has
no
data
at
this
point
to
evaluate
potential
chromium
contamination
from
the
chamber.
One
could
argue
that
EPA
should
monitor
chromium
­
if
for
no
other
reason
than
to
characterize
the
long­
term
performance
of
the
chambers.
How
crucial
is
chromium
data?
To
the
evaulation
of
coatings
performance,
to
characterization
of
the
CCA
wood
substrate,
to
evaulation
of
the
test
chambers
and
the
overall
protocol?
