November
29,
2004
MEMORANDUM
SUBJECT:
Additional
Explanation
of
the
Ecological
Risk
Assessment
for
Members
of
the
Plywood
and
Composite
Wood
Products
(
PCWP)
Source
Category
FROM:
Scott
Jenkins
Risk
and
Exposure
Assessment
Group
(
C404­
01)

TO:
David
E.
Guinnup,
Leader
Risk
and
Exposure
Assessment
Group
(
C­
404­
01)

Background
To
determine
whether
low­
risk
PCWP
sources
are
likely
to
cause
adverse
environmental
effects
due
to
emissions
of
hazardous
air
pollutants
(
HAP),
EPA
performed
a
screening
assessment
of
ecological
risks
from
these
sources.
The
assessment
is
described
in
the
memo
dated
January
28,
2004
from
Nancy
Jones
and
Lesley
Stobert
to
Dennis
Pagano
and
Maria
Pimentel
titled,
"
Multipathway
and
Ecological
Risks
from
Model
PCWP
Facilities"
(
see
appendix
A).
The
assessment
indicates
that
emissions
of
HAP
from
low­
risk
PCWP
sources
are
unlikely
to
pose
significant
risk
to
ecological
receptors.
The
purpose
of
this
memo
is
to
provide
additional
information
explaining
how
that
assessment
was
conducted.

Choice
of
HAP
The
ecological
assessment
focused
on
HAP
that
are
emitted
by
PCWP
facilities
and
that
have
the
potential
to
persist
in
the
environment
and
bioaccumulate.
The
list
of
persistent
and
bioaccumulative
HAP
(
PB
HAP)
is
described
in
EPA's
Air
Toxics
Risk
Assessment
Reference
Library
(
http://
www.
epa.
gov/
ttn/
fera/
risk_
atra_
main.
html).
We
did
not
evaluate
inhalation
risks
of
non­
PB
HAP
to
ecological
receptors
explicitly.
Rather,
we
assert
that
the
acute
and
chronic
dose­
response
values
for
human
inhalation
exposure,
which
will
be
used
by
PCWP
facilities
to
demonstrate
their
low
risk
status,
are
protective
of
inhalation
exposures
that
may
be
experienced
by
terrestrial
animals.
Human
dose­
response
threshold
values
are
derived
from
studies
that
consider
human
data
and
data
from
laboratory
animals.
With
the
addition
of
uncertainty
factors,
the
final
dose­
response
threshold
values
are
generally
significantly
lower
than
the
level
observed
to
cause
an
adverse
effect
in
exposed
animals.
Therefore,
if
the
maximum
inhalation
hazard
to
2
humans,
which
is
the
major
basis
for
the
low­
risk
demonstration,
is
below
the
level
of
concern,
we
do
not
expect
adverse
effects
on
environmental
receptors
due
to
inhalation
exposures.
We
have
tested
this
assertion
by
comparing
available
ecological
threshold
concentrations
in
air
with
the
corresponding
human
health­
based
reference
concentrations
for
several
key
compounds
emitted
by
PCWP
sources.
For
each
HAP
evaluated,
the
available
data
indicate
that
human
inhalation
dose­
response
values
are
protective
for
inhalation
exposures
to
ecological
receptors.
While
ecological
threshold
data
are
not
available
for
every
potential
endpoint
of
concern
for
every
HAP
emitted
by
this
source
category,
we
maintain
that
this
principle
will
likely
hold
true
across
HAP
and
endpoints.

Assumptions
Because
this
is
a
screening
assessment
rather
than
a
site­
specific
assessment,
we
made
several
ecosystem­
protective
assumptions.
We
derived
estimated
worst­
case
media
concentrations
by
assuming
the
maximum
air
concentrations
and
the
maximum
deposition
rates
occurred
at
the
same
location,
although
this
is
often
not
the
case.
We
examined
six
locations
representing
diverse
meteorological
conditions
and
for
the
final
assessment
we
used
the
location
providing
the
highest
predicted
HAP
concentrations.
We
used
the
most
conservative
ecological
screening
values
readily
available
(
see
Appendices)
which
may
overestimate
the
potential
for
toxicity
to
site­
specific
populations
and
communities.
Finally,
we
assumed
100
percent
bioavailability
of
the
HAP
although
site­
specific
bioavailability
is
often
much
less.

We
also
made
several
assumptions
that
were
not
necessarily
ecosystem­
protective.
The
pathways
and
receptors
evaluated
(
see
appendix
A)
were
assumed
to
be
representative
of
sensitive
individuals,
populations,
and
communities
(
including
endangered
species)
that
could
be
present
near
a
PCWP
facility.
Actual
site­
specific
sensitivities
to
HAP
and
the
sensitivities
to
HAP
of
virtually
all
threatened
or
endangered
species
are
unknown.
Additionally,
since
we
focused
this
assessment
on
the
impact
of
an
individual
PCWP
facility,
we
did
not
account
for
background
exposure
to
HAP
or
for
exposure
to
other
environmental
stressors.
However,
it
is
our
opinion
that
the
combination
of
assumptions
made
for
this
ecological
screening
assessment
represents
a
scenario
which
is
ecosystem­
protective
overall.

Calculation
of
Potential
Ecological
Hazard
To
determine
the
potential
for
ecological
hazard
we
used
the
hazard
quotient
method,
which
calculates
the
ratio
of
the
estimated
environmental
media
HAP
concentrations
to
the
appropriate
ecological
screening
values.
The
ecological
screening
values
used
are
estimates
of
the
maximum
concentration
that
should
not
affect
survival,
growth,
or
reproduction
of
sensitive
species
after
long­
term
(>
30
days)
exposure
to
HAP.
The
specific
screening
values
used
in
the
current
ecological
assessment
are
provided
in
the
original
ecological
assessment
memo
(
appendix
A)
and
the
methodology
used
to
derive
screening
values
is
provided
in
the
draft
secondary
lead
smelters
analysis
(
see
appendix
B).
3
Results
The
results
of
our
ecological
assessment
demonstrate
that
for
all
pollutants
assessed,
and
for
all
pathways
assessed,
the
ecological
hazard
quotient
values
are
less
than
1.
The
highest
hazard
quotient
is
0.043,
or
approximately
20
times
below
a
level
of
potential
concern.
Given
this
result,
and
the
ecosystem­
protective
nature
of
the
assessment
scenario,
we
believe
it
is
not
likely
that
any
of
the
HAP
evaluated
would
pose
an
ecological
risk
to
ecosystems
near
a
PCWP
facility.
4
OAQPS:
ESD:
REAG:
SJenkins:
bmiles:
x5648:
11/
29/
04
APPENDIX
A:
MULTIPATHWAY
AND
ECOLOGICAL
RISKS
FROM
MODEL
PCWP
FACILITIES
APPENDIX
B:
DRAFT
SECONDARY
LEAD
ASSESSMENT
