UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
EPA
Clarifying
Questions
Regarding
the
USDA
document
"
Economic
Impact
of
the
Chlorpyrifos­
methyl
Phase­
out
in
U.
S.
Wheat
Storage"

FROM:
Bill
Gross,
Entomologist
Herbicide
and
Insecticide
Branch
Tim
Kiely,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THRU:
Arnet
Jones,
Chief
Herbicide
and
Insecticide
Branch
David
Widawsky,
Chief
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

TO:
Jackie
Mosby
Special
Review
and
Reregistration
Division
(
7508C)

The
following
is
a
list
of
clarifying
economic
and
biological
questions
regarding
the
findings
as
reported
in
the
USDA
funded
document
titled
"
Economic
Impact
of
the
Chlorpyrifosmethyl
Phase­
out
in
U.
S.
Wheat
Storage".

Biological
Questions
The
Chlorpyrifos­
methyl
Economic
Impact
Report
place
a
lot
of
emphasis
on
the
dollar
losses
in
stored
wheat
from
insect
infestations
in
the
absence
of
chlorpyrifos­
methyl.
We
assume
that
your
estimates
are
based
on
estimates
of
losses
to
the
rice
weevil,
in
that
CPM
does
not
control
the
lesser
grain
borer.
Can
you
elaborate
on
this?

Let's
assume
that
a
grower
stores
his/
her
wheat
on
farm,
cleans
the
empty
grain
bin
thoroughly
of
all
residual
stored
grain
insect
pests
before
harvest,
stores
the
wheat
without
the
2
application
of
a
grain
protectant,
and
the
stored
wheat
has
a
low
moisture
content.
What
are
the
estimated
losses
that
this
grower
could
expect
to
incur
at
the
grain
elevator?

If
Storicide
were
not
available
in
its
present
form
(
cyfluthrin
and
chlorpyrifos­
methyl)
and
the
two
products
were
registered
separately
as
grain
protectants,
can
you
estimate
the
losses
in
stored
wheat
to
lesser
grain
borer
and
rice
weevil
when
these
products
are
used
alone?

We
are
aware
that
the
lesser
grain
borer
and
rice
weevil
do
co­
exist;
however,
it
is
common
to
find
the
rice
weevil
in
greater
numbers
in
the
southern
wheat
production
regions,
and
the
lesser
grain
borer
in
the
northern
and
plains
wheat
production
regions.
Assuming
that
good
stored
grain
insect
pests
management
practices
are
observed
in
all
regions,
can
you
estimate
the
expected
losses
at
the
grain
elevators,
based
on
pests
presence
in
each
respective
region?

In
the
Efficacy
and
Cost
Table
of
your
Summary
Report,
you
indicate
that
Spinosad
is
not
effective
against
the
weevils;
however
some
literature
do
not
support
your
claim.
(
Liang
Fang,
Bhadriraju
Subramanyam
and
Frank
H.
Arthur.
Effectiveness
of
Spinosad
on
Four
Classes
of
Wheat
Against
Five
Stored­
Product
Insects.
Journal
of
Economic
Entomology,
95(
3):
640­
650
(
2002).)
In
addition,
efficacy
data
on
Spinosad
against
stored­
product
insect
pests
under
an
Experimental
Use
Permit
is
still
being
collected
Economic
Questions
The
estimated
loss
of
$
14.64
million
without
chlorpyrifos­
methyl
available
for
use
assumes
that
every
bushel
currently
treated
with
chlorpyrifos­
methyl
(
183
million
bushels)
will
receive
a
$
0.10
discount
in
the
absence
of
chlorpyrifos­
methyl
(
less
the
cost
of
chlorpyrifos­
methyl,
$
0.02
per
bushel).

A)
What
is
the
basis
for
the
assumption
that
every
bushel
currently
treated
with
chlorpyrifos­
methyl
will
receive
the
discount
if
chlorpyrifos­
methyl
is
no
longer
available
for
use
on
stored
wheat?
Page
20
of
the
assessment
states
that
"
Neither
the
presence
nor
the
abundance
of
insect­
damage
kernels
was
significantly
associated
with
a
greater
risk
of
price
discount,
which
appeared
to
indicate
a
tolerance
of
live
insects
and
their
damage
on
the
part
of
many
elevator
managers".
Why
would
you
assume
this
would
be
different
without
chlorpyrifos­
methyl
available
for
use?
What
proportion
of
the
treated
bushels
receive
the
discount
currently?
Is
there
any
evidence
to
suggest
that
the
bushels
currently
treated
with
chlorpyrifos­
methyl
would
receive
a
different
discount
than
if
chlorpyrifosmethyl
were
not
available
for
use,
and
users
were
applying
either
cyfluthrin
or
spinosad?
Also,
Table
8
suggests
that
no
more
than
30%
(
and
as
little
as
6%)
of
wheat
growers
receive
a
discount
from
elevator
managers
for
insect
damage.

B)
What
is
the
basis
for
the
assumption
of
a
$
0.10
per
bushel
discount?
Table
8
suggests
discounts
ranging
from
$
0.02
per
bushel
to
$
0.08
per
bushel.
3
C)
What
is
the
basis
for
the
estimated
cost
per
bushel
of
chemical
insect
control?
The
cost
for
each
active
ingredient
listed
was
presented
as
a
table
during
the
presentation
to
US
EPA.
