While
we
do
not
believe
that
the
proposed
requirements
for
area
sources
pose
more
than
a
minimal
burden
to
those
sources,
we
specifically
ask
for
comment
on
methods
by
which
EPA
could
apply
the
additional
regulatory
burden
being
proposed
by
this
rule
to
only
those
area
sources
which
pose
significant
risks
to
human
health.
For
example,
we
seek
comments
on
whether
there
could
be
a
methodology
by
which
facilities
could
conduct
site
specific
risk
assessments
to
demonstrate
that
their
PCE
emissions
pose
cancer
risk
levels
that
are
less
than
1­
in­
1
million,
with
a
hazard
index
of
less
than
one,
and
with
no
acute
or
adverse
environmental
effects,
and
thereby
avoid
the
additional
requirements
that
would
otherwise
apply
under
the
proposed
rule
revisions.
Comments
should
address
whether
such
an
approach
is
feasible
(
for
example,
if
facilities
would
be
able
to
conduct
these
risk
assessments),
the
legal
authority
for
such
an
approach,
the
methodology
sources
would
use
for
conducting
risk
assessments,
the
specific
criteria
by
which
potential
"
low­
risk"
sources
would
be
evaluated,
the
mechanism
for
evaluating
and
determining
whether
source
risk
assessments
meet
those
criteria,
how
the
process
would
be
implemented
by
federal
and/
or
state
and
local
agencies,
how
it
would
be
enforced
(
for
example,
through
a
permitting
program
or
other
regulatory
structure
to
ensure
that
any
sources
found
to
be
"
low­
risk"
remain
so),
and
what
would
be
the
consequences
if
and
when
a
source
for
whatever
reason
is
found
to
no
longer
qualify
as
a
"
low­
risk"
source.
