June
7,
2002
Donald
R.
Lynam
Vice
President,
Air
Conservation
Ethyl
Corporation
330
South
Fourth
Street
Richmond,
VA
23219­
4304
Dear
Dr.
Lynam,

On
March
28,
2002,
the
Ethyl
Corporation
(
Ethyl)
submitted
to
the
Environmental
Protection
Agency
(
EPA)
a
draft
peer­
reviewed
health
study
protocol
for
MMT
and
a
draft
peer­
reviewed
final
report,
as
required
under
the
Alternative
Tier
2
Health
Effects
Testing
Requirements.
The
draft
peer­
reviewed
protocol
submission
deals
with
protocols
associated
with
the
90­
day
primate
pharmacokinetic
(
PK)
health
study.
The
draft
peer­
reviewed
final
report
is
the
result
of
the
90­
day
exposure
of
young
adult
and
aged
rats
PK
health
study.
These
submissions
are
part
of
the
requirements
that
were
finalized
in
the
notification
received
by
Ethyl
on
May
25,
2000.
This
letter
provides
EPA's
comments
on
these
submissions.

In
regard
to
the
draft
peer­
reviewed
primate
PK
protocol,
we
believe
this
protocol
fulfills
EPA's
study
requirements.
We
concur
with
the
Technical
Advisory
Panel
(
TAP)
that
this
study
is
needed
to
provide
the
information
necessary
to
assess
the
human
health
risks
of
manganese
exposure
due
to
substantial
interspecies
response
variability.
We
also
believe
the
analyses
used
to
determine
the
proposed
exposure
concentrations
and
number
of
animals
needed
at
each
point
and
exposure
level
are
appropriate.
The
Chemical
Industry
Institute
of
Toxicology
(
CIIT)
has
adequately
addressed
the
TAP
concerns
regarding
the
experimental
time
points,
housing,
diets
and
evaluations
of
potential
pathogens
in
the
test
subjects.
Finally
we
strongly
concur
with
the
TAP
that
magnetic
resonance
(
MR)
brain
scanning
would
be
a
valuable
scientific
addition
to
the
primate
PK
study.
We
encourage
the
conduct
of
these
MR
measures
so
long
as
they
do
not
delay
the
required
primate
PK
study.

In
regard
to
the
draft
peer­
reviewed
final
report
on
the
90­
day
exposure
of
young
adult
and
aged
rats
PK
health
study,
the
conclusions
presented
seem
to
be
adequate
and
supported
by
the
results
of
the
study.
Additionally,
the
study
report
adequately
addresses
the
peer
reviewer
concerns.
­
2­

We
look
forward
to
Ethyl's
submission
of
the
revised
draft
protocol
and
the
final
report
as
required
under
the
notification.
If
you
have
any
questions
concerning
our
review,
please
contact
Joe
Sopata
of
my
staff
at
(
202)
564­
9034.

Sincerely,

/
s/

Robert
E.
Larson,
Acting
Director
Transportation
and
Regional
Programs
Division
cc:
Monica
Alvarez,
ORD/
OSP
J.
Michael
Davis,
ORD/
NCEA
Stan
Durkee,
ORD/
OSP
Hal
Zenick,
ORD/
NHEERL
William
Russo,
ORD/
NHEERL
Tim
Backstrom,
OGC
Kevin
Fast,
Hunton
&
Williams
