UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
DATE:
September
12,
2003
SUBJECT:
Fenthion
Response
to
LCMCD
Comments
TO:
Fenthion
RED
Team
FROM:
Jackie
Mosby,
Acting
Branch
Chief
Reregistration
Branch
1
Special
Review
and
Reregistration
Division
During
the
comment
period
for
Bayer
Environmental
Science's
(
Bayer)
voluntary
cancellation
request
for
its
fenthion
registrations,
the
Agency
received
three
sets
of
comments
in
support
of
the
cancellation.
After
the
close
of
the
comment
period,
but
before
the
Agency
made
its
final
determination
on
the
cancellation
request,
the
Agency
received
one
additional
set
of
comments.
The
additional
set
of
comments
supports
the
continued
registration
of
fenthion
products.
The
Agency
reviewed
all
of
the
comments
and
decided
to
grant
Bayer's
voluntary
cancellations.
Please
see
the
Federal
Register
Notice
titled
"
Fenthion;
Product
Registrations
Cancellation
Order"
(
FRL­
7324­
2)
for
details
on
the
cancellation
order.
This
memorandum
specifically
responds
to
the
set
of
comments
in
support
of
continuing
the
fenthion
registrations.

The
submitter
of
the
comments
provided
the
following
reasons
for
supporting
the
continued
registration
of
fenthion:

1.
No
Adverse
Effects
Associated
with
Use
of
Fenthion
The
commenter
made
the
statement
that
"
Lee
County
Mosquito
Control
District,
Fort
Myers,
Florida,
has
been
applying
fenthion
for
adult
mosquito
control
since
July
2,
1965,
without
any
adverse
effects
to
the
environment,
including
birds."
The
commenter
cites
as
evidence
the
fact
that
fenthion
has
been
sprayed
in
the
area
around
or
adjacent
to
the
J.
N.
"
Ding"
Darling
National
Wildlife
Refuge,
located
on
Sanibel
Island,
for
ten
years,
and
there
have
been
no
bird
kills
in
the
refuge
associated
with
the
spraying
of
fenthion.

Agency
Response
The
Agency
commends
the
commenter
for
its
diligence
in
spraying
and
compliance
with
the
label
directions.
As
such,
there
should
be
no
incidents
on
the
refuge
as
long
as
fenthion
is
being
applied
according
to
the
label
directions.
Spraying
is
not
allowed
over
the
refuge,
and
drift
into
that
area
should
not
be
occurring;
therefore,
there
should
be
no
incidents,
as
there
is
no
exposure.
The
real
question
concerning
risk
to
birds
is
whether
birds
that
are
in
sprayed
areas
are
adversely
affected.
The
information
provided
on
the
Ding
Darling
refuge
is
not
probative
of
that
point.

Non­
target
species
(
i.
e.
birds)
in
areas
where
fenthion
is
sprayed,
however,
could
be
adversely
affected.
The
Agency's
Interim
Reregistration
Eligibility
Decision
(
IRED)
on
fenthion
concluded
that
acute
dietary
risk
to
birds
from
mosquito
adulticide
applications
was
"
high"
based
on
available
information.
The
Agency
also
found
"
that
fenthion
spraying,
especially
repeated
at
frequent
intervals,
may
cause
mortality
in
a
variety
of
bird
species."

The
IRED
also
discusses
a
number
of
incidents
of
bird
mortality
resulting
from
the
spraying
of
fenthion.
The
IRED
focuses
particularly
on
incidents
reported
by
the
US
Fish
and
Wildlife
Service
(
FWS)
that
occurred
on
Marco
Island.
According
to
the
FWS,
spraying
of
fenthion
resulted
in
mortality
of
at
least
16
bird
species
over
approximately
an
eleven­
month
time
span.
See
memorandum
by
W.
Erickson,
re:
Fenthion
Marco
Island
Incidents.
The
Agency
is
also
aware
of
a
number
of
other
bird
incidents
related
to
fenthion.
See
memorandum
from
M.
Powell
to
K.
David,
re:
Addendum
to
EFED's
IRED
Chapter
for
Fenthion,
Based
on
Incident
Reports
(
July
31,
1996).

EPA
does
not
believe
that
the
information
provided
on
the
J.
N.
"
Ding"
Darling
National
Wildlife
Refuge
demonstrates
that
fenthion
does
not
present
an
unreasonable
risk
of
adverse
effects
to
birds.

2.
More
Than
One
Pesticide
for
Mosquito
Control
Needed
The
commenter
stated
that
there
are
"
few
tools
for
public
that
public
health
vector
control
specialists
currently
have
available
for
adult
mosquito
control."
The
commenter
stated
that
there
are
two
products
available
that
are
equally
efficacious
for
public
health
control,
fenthion
and
naled,
but
that
both
are
necessary
in
rotation
in
order
to
avoid
pest
resistence
issues.

Agency
Response
The
Agency
agrees
with
the
commenter
that
naled
is
an
efficacious
and
appropriate
alternative
to
fenthion.
The
Agency
also
agrees
that
it
is
useful
to
have
more
than
one
"
tool"
available
to
address
a
pest
problem.
However,
when
the
Agency
considered
the
risks
and
benefits
for
fenthion,
as
required
by
the
Federal
Insecticide,
Fungicide,
and
Rodenticide
Act
(
FIFRA),
the
risks
posed
to
birds
and
aquatic
invertebrates
were
found
to
outweigh
the
benefits
from
its
use.

3.
There
Are
Problems
with
the
Alternatives
to
Fenthion
The
commenter
stated
that
alternatives
other
than
naled,
such
as
synthetic
pyrethroids
and
malathion
may
not
be
used
in
Lee
County,
Florida,
or
in
the
case
of
natural
pyrethrins,
are
in
limited
supply.
Agency
Response
The
Agency
addressed
the
issue
of
alternatives
to
fenthion
in
the
IRED
(
see
IRED
Sections
IV.
E
and
IV.
F).
The
Agency
agrees
with
the
commenter
that
there
may
be
drawbacks
to
several
of
the
alternatives;
however,
naled
is
an
efficacious
and
appropriate
alternative
to
fenthion,
as
used
in
Lee
County.
FIFRA
does
not
require
that
multiple
alternatives
to
a
pesticide
exist
in
order
for
the
Agency
to
issue
a
cancellation
order
under
FIFRA
§
6(
f).

4.
CDC
and
HHS
Appear
to
Support
the
Continued
Use
of
Fenthion
The
commenter
stated
a
Department
of
Health
and
Human
Services
(
HHS)
in
the
Centers
for
Disease
Control
and
Prevention
(
CDC)
official,
Dr.
Duane
Gubler,
stated
that
the
loss
of
a
single
mosquito
control
tool
would
"
seriously
compromise"
the
CDC's
ability
to
"
prevent
and
control
vector­
borne
disease
in
the
[
United
States]."

The
commenter
also
stated
that
the
Agency
cannot
cancel
fenthion,
in
light
of
its
obligations
under
FIFRA
§
4(
n)
to
consult,
when
requested
by
the
registrant,
with
the
HHS
before
approving
a
request
for
a
voluntary
cancellation.

Agency
Response
Bayer
requested,
pursuant
to
FIFRA
§
4(
n),
that
EPA
consult
with
HHS
before
canceling
its
fenthion
registrations.
After
consulting
with
HHS,
EPA
may
determine
that
the
benefits
of
the
public
health
or
vector
control
pesticide
are
so
significant
as
to
warrant
a
commitment
by
HHS
to
conduct
(
or
arrange
to
conduct)
studies
needed
to
support
continued
registration
of
the
pesticide.
EPA
sent
a
letter
to
CDC
requesting
consultation
and
inviting
CDC
to
submit
additional
information
on
fenthion.
EPA
received
a
response
from
HHS,
dated
August
1,
2003,
stating
that
it
does
not
take
exception
to
our
decision
to
cancel
fenthion,
but
indicating
that
more
than
one
tool
should
remain
available
for
mosquito
control.
EPA
believes
it
has
fulfilled
its
consultation
requirement
under
FIFRA
§
4(
n).

EPA
understands
that
individuals
within
HHS
and
CDC
may
support
the
continued
registration
of
fenthion;
however,
even
considering
available
information
from
HHS
and
CDC,
EPA
has
yet
to
find
fenthion
eligible
for
reregistration.
The
Agency
does
not
believe
the
commenter
has
provided
sufficient
justification
to
merit
denying
the
voluntary
cancellation
request.

5.
Outstanding
Data
Requirements
The
commenter
stated
that
there
have
been
discrepancies
between
the
data
gaps
EPA
identified
in
the
IRED
and
the
studies
EPA
has
included
in
the
Data
Call­
In
(
DCI)
notices.
The
commenter
suggested
that
there
were
no
outstanding
data
requirements
on
which
EPA
could
have
pursued
suspension
or
cancellation
under
FIFRA
§
4(
n)
or
§
6(
b).
The
commenter
also
appeared
to
suggest
that
this
confusion
led
Bayer
to
conclude
that
it
did
not
have
an
economic
stake
in
the
fenthion
registrations.
The
commenter
referenced
three
studies
in
particular:
developmental
neurotoxicity,
ecotoxicity,
and
worker
exposure.

Agency
Response
With
respect
to
the
studies
the
commenter
referenced,
EPA
notes
the
following:

Developmental
neurotoxicity
­
as
the
commenter
points
out,
this
study
was
included
in
a
1999
DCI.
Bayer's
fenthion
registrations
were
subject
to
this
DCI,
and
Bayer
was
required
to
conduct
the
study.
The
commenter
suggests
that
because
Bayer
went
on
to
cancel
the
food
uses
associated
with
fenthion,
the
study
is
not
necessary;
however,
EPA
has
never
waived
this
data
requirement
for
the
fenthion
registrations.
Therefore,
it
is
still
a
data
gap
and
would
need
to
be
addressed
in
order
for
Bayer
to
continue
its
fenthion
registrations.

Ecotoxicity
and
worker
exposure
­
while
these
studies
were
listed
as
data
gaps
in
the
IRED,
EPA
decided
not
to
issue
a
DCI
for
them,
due
to
the
fact
that
Bayer
requested
voluntary
cancellation
of
all
its
fenthion
registrations.
However,
if
another
registrant
chose
to
apply
for
a
fenthion
registration
in
the
future,
and
EPA
determined
that
the
application
for
registration
met
the
standard
for
registration
and
was
eligible
for
reregistration,
EPA
would
either
issue
a
DCI
at
that
time,
require
that
the
data
gaps
be
filled
before
registering
the
product,
or,
if
appropriate,
condition
the
registration
on
the
fulfillment
of
the
outstanding
data
gaps.

The
Agency
is
not
privy
to
all
the
factors,
economic
and
otherwise,
Bayer
considered
in
deciding
to
request
voluntary
cancellation.
In
determining
whether
to
grant
a
voluntary
cancellation
request,
it
is
immaterial
whether
EPA
could
have
cancelled
the
product
on
its
own
initiative.
Furthermore,
EPA
does
not
believe
that
its
failure
to
issue
a
DCI
for
a
pesticide
(
or
potential
confusion
over
data
gaps)
is
a
reason
to
deny
a
voluntary
cancellation
request.
As
noted
above,
EPA
has
fulfilled
its
obligation
under
FIFRA
§
4(
n).
