Document ID: EPA-HQ-OPP-2004-0220-0005
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-07-22T04:00Z

UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
July
19,
2004
MEMORANDUM:

SUBJECT:
2,4­
DB
[
4­(
2,4­
dichlorophenoxy)
butyric
acid]
and
2,4­
DB
dimethylamine
salt
(
PC
Codes
030801,
030819):
REVISED
Product
Chemistry
and
Residue
Chemistry
Summary
Documents
for
the
Reregistration
Eligibility
Decision
Document
(
RED).
Reregistration
Case
0196.
DP
Barcode.
D291212.

FROM:
Danette
Drew,
Chemist
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

THROUGH:
Whang
Phang,
Branch
Senior
Scientist
Reregistration
Branch
1
Health
Effects
Division
(
7509C)

TO:
Mika
Hunter
Special
Review
Branch
Special
Review
and
Reregistration
Division
(
7508C)

Attached
is
the
revised
product
chemistry
and
residue
chemistry
considerations
for
the
Reregistration
Eligibility
Decision
for
2,4­
DB
acid
[
4­(
2,4­
dichlorophenoxy)
butyric
acid]
and
its
dimethylamine
salt.
This
revision
reflects,
where
appropriate,
comments
made
by
the
2,4­
DB
Task
Force
under
the
Phase
1
error­
only
comment
period.
Comments
regarding
the
water
solubility,
octanol/
water
coefficients
and
dissociation
constant
of
2,4­
DB
will
be
addressed
during
Phase
3
as
will
comments
regarding
the
product
chemistry
requirements
for
the
49.2%
formula
intermediary
2,4­
DB
dimethylamine
salt.
This
document
supercedes
D290793
dated
12/
11/
03.
2
Executive
Summary
2,4­
DB
[
4­(
2,4­
dichlorophenoxy)
butyric
acid]
is
a
plant
growth
regulator
and
herbicide
registered
for
use
on
alfalfa,
clover,
peanuts,
soybean,
peppermint,
spearmint,
and
trefoil.
It
is
currently
manufactured
as
the
acid
(
030801)
and
the
dimethylamine
salt
(
030819);
no
other
salt
or
ester
products
are
currently
registered.
End­
use
products
are
formulated
either
as
soluble,
emulsifiable,
or
flowable
concentrates
(
SC/
L,
EC,
or
FlC).
2,4­
DB
can
be
applied
either
as
a
broadcast
application
early
season,
or
a
directed
spray
late
season.
Ground
or
aerial
applications
may
be
made.
Maximum
label
application
rates
for
food/
feed
crops
range
from
0.19
lb
ae
(
acid
equivalents)/
A
to
0.68
lb
ae/
A.

Tolerances
for
residues
of
2,4­
DB
in
plant
commodities
are
currently
expressed
as
the
combined
residues
of
the
herbicide
4­(
2,4­
dichlorophenoxy)
butyric
acid
and
its
metabolite
2,4­
dichlorophenoxyacetic
acid
(
2,4­
D)
which
is
also
a
registered
active
ingredient.
Current
tolerance
levels
are
set
at
0.2
ppm
(
based
on
negligible
residues)
in
alfalfa;
clover;
mint,
hay;
peanut;
trefoil,
birdsfoot;
soybean;
and
soybean,
hay.
No
tolerances
in
livestock
commodities
or
food/
feed
processed
commodities
have
been
established.

The
qualitative
nature
of
the
2,4­
DB
residue
in
plant
and
livestock
commodities
is
adequately
understood
based
on
acceptable
metabolism
studies
in
alfalfa,
peanuts,
soybeans,
dairy
cows
and
laying
hens.
Plant
and
livestock
metabolism
studies
were
conducted
using
the
acid
form
of
2,4­
DB(
030801).
The
Agency
granted
a
waiver
(
5/
11/
94
Greybeard
Committee
memorandum)
for
metabolism
studies
for
the
DMA
salt
concluding
that
studies
for
the
acid
will
suffice
to
characterize
metabolism
for
both
the
salt
and
the
acid.

In
plants,
2,4­
DB
is
metabolized
in
several
ways
including
side­
chain
degradation
[
to
form
2,4­
dichlorophenoxyacetic
acid
(
2,4­
D)
and
related
products],
ring
hydroxylation,
position
shift
of
the
chlorine
atoms
on
the
ring,
and
dechlorination.
Incorporation
of
radioactivity
into
sugar,
protein,
and
other
natural
constituents
also
resulted
from
metabolism
of
the
ring­
labeled
compound.
The
parent
2,4­
DB
(
acid)
is
the
primary
residue
found
in
most
crop
matrices.

In
the
hen
study,
the
highest
radioactivity
was
found
in
eggs,
fat,
and
liver.
Most
of
the
residue
was
identified
as
the
unchanged
parent
compound.
In
dairy
cows,
the
highest
radioactivity
was
found
in
milk,
liver,
and
kidney;
residues
in
muscle
and
fat
were
very
low.
Metabolites
included
2,4­
DB
per
se,
the
glycine
conjugate
of
2,4­
DB,
and
2,4­
dichlorophenol.

The
HED
Metabolism
Committee
concluded
that
the
residue
to
be
regulated
in
plant
and
livestock
commodities
is
2,4­
DB
per
se,
and
that
2,4­
D
need
not
be
included
in
the
tolerance
expression.
The
metabolite
1,4­
benzoquinone
was
excluded
from
the
tolerance
expression
because
it
is
significant
only
in
certain
animal
feedstuffs,
and
other
residues
were
excluded
because
they
each
comprise
only
a
small
portion
of
the
total
residue.
2,4­
DB
parent
appears
as
the
major
compound
in
many
of
the
plant
and
livestock
matrices,
and
the
2,4­
D
metabolite
is
present
only
at
low
levels.
It
is
generally
agreed
that
2,4­
DB
(
and
other
straight­
chain,
even­
numbered
higher
analogues)
are
3
toxic
only
to
plants
that
possess
an
active
beta­
oxidation
enzyme
system
capable
of
degrading
the
herbicide
to
the
growth
regulator
compound
2,4­
D;
it
is
the
2,4­
D
degradate
that
accumulates
in
regions
of
active
metabolism
and
causes
cell
division,
cell
enlargement,
and
(
if
present
in
sufficient
concentrations)
cell
death
(
D.
Miller,
11/
14/
95
and
1/
29/
96).

Based
on
the
HED
Metabolism
Committee
decision
and
available
residue
field
trial
data
for
2,4­
DB,
and
in
maintaining
consistency
with
the
2,4­
D
recommended
tolerances
(
D287660,
W.
Hazel,
undergoing
completion),
the
tolerance
for
residues
of
2,4­
DB
in
plant
commodities
should
be
expressed
as
residues
of
2,4­
DB,
both
free
and
conjugated,
determined
as
the
acid.
The
reassessed
tolerances
for
plants
are
listed
as
follows:
alfalfa,
forage
(
0.70
ppm);
alfalfa,
hay
(
2.0
ppm);
clover,
forage
and
clover,
hay
(
insufficient
data
available);
peppermint,
tops
and
spearmint,
tops
(
0.20
ppm);
soybean,
seed
(
0.50
ppm),
soybean,
forage
(
0.70
ppm),
soybean,
hay
(
2.0
ppm);
peanut
(
0.05
ppm);
trefoil,
forage
(
0.70
ppm)
and
trefoil,
hay
(
2.0
ppm).

As
with
plant
commodities,
the
tolerance
for
residues
of
2,4­
DB
in
livestock
commodities
should
be
expressed
as
residues
of
2,4­
DB,
both
free
and
conjugated,
determined
as
the
acid.
The
appropriate
tolerance
for
2,4­
DB
is
0.05
ppm
(
LOQ)
in
the
meat
byproducts
of
cattle,
goats,
hogs,
horses,
and
sheep.
There
is
no
reasonable
expectation
of
the
transfer
of
residues
of
2,4­
DB
from
feedstuffs
to
livestock
meat,
fat
or
milk;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
milk
and
in
meat
and
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required.

The
poultry
feeding
study
(
MRID
44997902)
indicates
that
residues
of
2,4­
DB
are
not
expected
to
transfer
to
poultry
eggs
and
tissues
as
a
result
of
the
current
registered
uses
of
2,4­
DB
on
poultry
feedstuffs;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
poultry
meat,
fat,
meat
byproducts
and
eggs
are
not
required.

Sufficient
data
are
available
to
determine
that
residues
of
2,4­
DB
do
not
significantly
concentrate
in
any
peanut,
soybean
or
mint
processed
food/
feed
item;
thus,
tolerances
are
not
required
for
the
processed
commodities
of
these
crops.

Adequate
tolerance
enforcement
methods
are
currently
available.
2,4­
DB
is
completely
recovered
(>
80%)
by
FDA
MultiResidue
Test
Method
402
(
PAM
Vol
I,
updated
10/
97).
The
Pesticide
Analytical
Manual
(
PAM)
Vol.
II,
lists
Method
I,
a
GC
method
with
microcoulometric
detection,
for
the
enforcement
of
tolerances
for
2,4­
DB
residues;
this
method
is
the
PAM
Vol.
I
method
for
chlorophenoxy
acid
residues
in
food.

2,4­
DB
Task
Force
(
consisting
of
A.
H.
Marks
and
Co.,
Ltd.,
Aceto
Agricultural
Chemicals,
and
Atanor
S.
A.)
submitted
GC/
ECD
(
gas
chromatography
with
electron­
capture
detection)
analytical
methods
that
determine
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
several
plant
and
livestock
commodities.
The
methods
were
found
to
be
adequate
for
data
collection.
If
the
4
submitted
GC/
ECD
analytical
method
for
plant
commodities
is
proposed
as
a
2,4­
DB
tolerance
enforcement
method
then
the
method
should
be
modified
to
include
determination
of
both
free
and
conjugated
2,4­
DB
and
an
independent
laboratory
validation
(
ILV)
should
be
performed.
If
the
GC/
ECD
method
is
proposed
as
the
enforcement
method
for
determining
2,4­
DB
in
livestock
commodities,
independent
laboratory
validation
of
the
method
should
be
performed.
Adequate
method
radiovalidation
data
have
been
submitted
for
livestock
commodities.

Product
Chemistry
Deficiencies
°
The
registrant
must
submit
the
data
required
in
the
attached
product
chemistry
data
summary
tables
(
pp
7­
13),
and
required
data
for
dibenzo­
p­
dioxins
and
dibenzofurans,
and
either
certify
that
the
suppliers
of
beginning
materials
and
the
manufacturing
process
for
the
2,4­
DB
products
have
not
changed
since
the
last
comprehensive
product
chemistry
review
or
submit
a
complete
updated
product
chemistry
data
package.
HED
has
no
objections
to
the
reregistration
of
2,4­
DB
with
respect
to
product
chemistry
data
requirements
if
these
data
are
submitted
for
review.

Residue
Chemistry
Deficiencies
860.1200
$
Labels
for
EPA
Reg.
No.
56077­
26
(
now
66222­
76)
and
EPA
Reg
No.
56077­
52
(
now
66222­
80)
only
prohibit
the
grazing
of
forage
or
feeding
of
hay
within
60
days
of
the
application
of
a
tank
mix
with
Lorax
50W
application,
and
there
is
no
indication
of
any
restriction
when
2,4­
DB
is
applied
alone.
The
restriction
should
be
against
feeding/
grazing
soybean
forage
and
harvesting
hay
for
60
days
following
any
2,4­
DB
application.

860.1340
°
The
submitted
plant
analytical
methods
are
adequate
for
data
collection
but
must
be
adequately
validated
for
each
study
for
which
it
is
used.
If
any
of
the
submitted
analytical
methods
for
plant
commodities
are
proposed
as
a
2,4­
DB
tolerance
enforcement
method
then
the
method
should
be
modified
to
include
determination
of
free
and
conjugated
2,4­
DB.
An
ILV
should
be
performed.

°
The
submitted
methods
for
livestock
commodities
are
adequate
for
data
collection.
The
radiovalidation
data
show
that
the
analytical
methods
adequately
recover
fortified
residues
of
2,4­
DB
from
whole
egg
and
aged
residues
of
2,4­
DB
from
poultry
fat,
poultry
liver,
and
goat
milk.
If
the
submitted
method
is
proposed
as
the
enforcement
method
for
determining
2,4­
DB
in
livestock
commodities
then
an
ILV
of
the
method
should
be
performed.
5
860.1500
°
Additional
field
trials
on
clover
forage
and
hay
are
required
at
the
maximum
label
rate
(
1.3
lb
ae/
A)
with
a
60­
day
PHI
to
reassess
the
2,4­
DB
tolerances.
Ten
additional
trials
are
recommended
in
the
following
regions:
1
(
Region1),
1
(
Region
2),
1
(
Region
4),
3
(
Region
5),
1
(
Region
6),
1
(
Region
7),
1
(
Region
8),
1
(
Region
9).

860.1650
°
Analytical
reference
standards
must
be
supplied
as
requested
by
the
EPA
National
Pesticide
Standards
Repository
for
2,4­
DB.
Standards
may
be
sent
to
:

USEPA
National
Pesticide
Standards
Repository/
Analytical
Chemistry
Branch/
OPP
710
Mapes
Road
Fort
George
G.
Meade,
MD
20755­
5350
cc
:
D.
Drew,
RF,
K.
Farwell
(
RRB1)
RDI:
RRB3
Team:
10/
20/
03;
ChemSAC:
11/
19/
03;
Whang
Phang
(
BSS,
RRB1)
7/
19/
04
6
O
Cl
Cl
O
O
­

NH2(
CH3)
2
+

O
Cl
Cl
O
OH
2,4­
DB
REREGISTRATION
ELIGIBILITY
DECISION
DOCUMENT:

PRODUCT
CHEMISTRY
CONSIDERATIONS
(
PC
Codes
030801
and
030819;
Case
No.
0196)

DP
Barcode
No.
D291212
DESCRIPTION
OF
CHEMICAL
2,4­
DB
[
4­(
2,4­
dichlorophenoxy)
butyric
acid]
is
a
plant
growth
regulator
and
herbicide
registered
for
use
on
alfalfa,
clover,
peanuts,
soybean,
peppermint,
spearmint,
and
trefoil.
It
is
currently
marketed
as
the
acid
(
030801)
and
the
dimethylamine
salt
(
030819);
no
other
salt
or
ester
products
are
currently
registered.

2,4­
DB
Acid
2,4­
DB
Dimethylamine
Salt
Empirical
Formula:
C
10
H
10
Cl
2
O
3
C
12
H
17
Cl
2
NO
3
Molecular
Weight:
249.1
293.9
CAS
Registry
No.:
94­
82­
6
­
PC
Code:
030801
030819
Color:
off­
white
Light
orange/
brown
Physical
State:
flakes/
powder
Viscous
liquid
Melting
Point:
113.5­
117.5

C
­
Water
Solubility:
46
ppm
Miscible
Vapor
Pressure:
7x10­
7
mm
Hg
­
Log
K
OW:
3­
4
­
7
MANUFACTURING
USE
PRODUCTS
An
Office
of
Pesticide
Programs
Information
Network
(
OPPIN
Query)
search
conducted
6/
30/
03
identified
five
2,4­
DB
acid
technical
products
and
one
2,4­
DB
DMA
Manufacturing
Use
Product
(
MP).
The
status
of
the
Product
Chemistry
Data
requirements
for
these
products
is
summarized
in
the
tables
below.
This
information
was
derived
from
reviews
available
in
the
registration
jackets
for
each
registered
technical
product
and
the
MP
as
of
7/
3/
03,
and
from
Health
Effects
Division
files.
For
the
technical
products,
which
are
all
similar
to
each
other,
physical
/
chemical
property
data
were
assumed
to
be
satisfied
for
all
technical
products
for
members
of
the
2,4­
DB
Task
Force,
if
these
data
were
available
for
any
of
the
products.
2,4­
DB
Task
Force
members
include
A.
H.
Marks
&
Company,
Ltd.,
Atanor
S.
A.,
and
Aceto
Agricultural
Chemicals
Corporation.
This
assumption
was
not
made
for
non­
Task
Force
companies
(
Drexel
Chemical
Company
and
Makhteshim­
Agan
of
North
America
Inc.).

The
Agency
issued
a
Data
Call­
In
(
DCI,
6/
87)
for
the
determination
of
15
chlorinated
dibenzo­
pdioxins
and
dibenzofurans
in
2,4­
DB
products.
A.
H.
Marks
&
Co.,
Atanor
S.
A.,
and
Cedar
(
transferred
to
Makhteshim­
Agan
of
North
America)
have
provided
analyses
indicating
that
these
impurities
are
not
present
at
levels
above
the
required
Limits
of
Detection
(
LODs)
in
their
products.
No
data
has
been
provided
for
the
Aceto
Agricultural
Chemicals
Corp.
or
Drexel
Chemical
Co.
products.

CONCLUSIONS
The
registrant
must
submit
the
data
required
in
the
attached
data
summary
tables,
and
required
data
for
dibenzo­
p­
dioxins
and
dibenzofurans,
and
either
certify
that
the
suppliers
of
beginning
materials
and
the
manufacturing
process
for
the
2,4­
DB
products
have
not
changed
since
the
last
comprehensive
product
chemistry
review
or
submit
a
complete
updated
product
chemistry
data
package.
HED
has
no
objections
to
the
reregistration
of
2,4­
DB
with
respect
to
product
chemistry
data
requirements
if
this
data
is
submitted
for
review.
8
Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
Aceto
Agricultural
Chemicals
Corp.
Product(
s):
98%
T
(
EPA
Reg.
No.
2749­
93)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
N
830.1600
Description
of
materials
used
to
produce
the
product
N
830.1620
Description
of
production
process
N
830.1670
Discussion
of
formation
of
impurities
N
830.1700
Preliminary
analysis
N
830.1750
Certified
limits
N
830.1800
Enforcement
analytical
method
N
830.6302
Color
Y
b
830.6303
Physical
state
Y
b
830.6304
Odor
Y
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
Y
b
830.6314
Oxidation/
reduction:
chemical
incompatibility
Y
b
830.6315
Flammability
N/
A
830.6316
Explodability
Y
b
830.6317
Storage
stability
Y
b
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
Y
b
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
Y
b
830.7050
UV/
visible
absorption
Y
b
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
Y
b
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
Y
b
830.7370
Dissociation
constant
Y
b
830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
Y
b
830.7840/
7860Water
solubility
Y
b
830.7950
Vapor
pressure
Y
b
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
b
Task
Force
data
for
similar
registered
products
are
available
to
fulfill
this
requirement.
9
10
Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
A.
H.
Marks
&
Company
Ltd
Product(
s):
96%
T
(
EPA
Reg.
No.
15440­
20)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
Y
457701­
01
830.1600
Description
of
materials
used
to
produce
the
product
Y
457701­
01
830.1620
Description
of
production
process
Y
457701­
02
830.1670
Discussion
of
formation
of
impurities
Y
457701­
03
830.1700
Preliminary
analysis
Y
457701­
05
830.1750
Certified
limits
Y
457701­
04,
­
05
830.1800
Enforcement
analytical
method
Y
457701­
05
830.6302
Color
Y
b
830.6303
Physical
state
Y
b
830.6304
Odor
Y
b
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
Y
b
830.6314
Oxidation/
reduction:
chemical
incompatibility
Y
b
830.6315
Flammability
N/
A
830.6316
Explodability
Y
b
830.6317
Storage
stability
Y
c
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
Y
b
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
Y
b
830.7050
UV/
visible
absorption
Y
b
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
Y
b
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
Y
b
830.7370
Dissociation
constant
Y
b
830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
Y
b
830.7840/
7860Water
solubility
Y
b
830.7950
Vapor
pressure
Y
b
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
b
No
MRIDs
provided.
See
David
Miller
review
of
2/
23/
96
11
c
No
MRID
provided.
See
Shyam
B.
Mathur
review,
2/
23/
96.

Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
Drexel
Chemical
Co.
Product(
s):
98%
T
(
EPA
Reg.
No.
19713­
124)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
N
830.1600
Description
of
materials
used
to
produce
the
product
N
830.1620
Description
of
production
process
N
830.1670
Discussion
of
formation
of
impurities
N
830.1700
Preliminary
analysis
N
830.1750
Certified
limits
N
830.1800
Enforcement
analytical
method
N
830.6302
Color
N
830.6303
Physical
state
N
830.6304
Odor
N
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
N
830.6314
Oxidation/
reduction:
chemical
incompatibility
N
830.6315
Flammability
N/
A
830.6316
Explodability
N
830.6317
Storage
stability
N
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
N
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
N
830.7050
UV/
visible
absorption
N
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
N
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
N
830.7370
Dissociation
constant
N
830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
N
830.7840/
7860Water
solubility
N
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
12
830.7950
Vapor
pressure
N
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
13
Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
Atanor
S.
A..
Product(
s):
98%
T
(
EPA
Reg.
No.
46146­
1)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
Y
459969­
01
830.1600
Description
of
materials
used
to
produce
the
product
Y
459969­
01
830.1620
Description
of
production
process
Y
459969­
01
830.1670
Discussion
of
formation
of
impurities
Y
459969­
01
830.1700
Preliminary
analysis
Y
459969­
01
830.1750
Certified
limits
Y
459969­
01
830.1800
Enforcement
analytical
method
Y
459969­
01
830.6302
Color
Y
459969­
04
830.6303
Physical
state
Y
459969­
04
830.6304
Odor
Y
459969­
04
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
Y
459969­
04
830.6314
Oxidation/
reduction:
chemical
incompatibility
N/
A
830.6315
Flammability
N/
A
830.6316
Explodability
N
830.6317
Storage
stability
N
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
N
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
Y
459969­
04
830.7050
UV/
visible
absorption
Y
459969­
04
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
Y
459969­
04
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
Y
459969­
04
830.7370
Dissociation
constant
Y
No
diss
const.

830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
Y
459969­
04
830.7840/
7860Water
solubility
Y
459969­
04
830.7950
Vapor
pressure
Y
459969­
04
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
14
15
Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
Makhteshim­
Agan
of
North
America
Inc
Product(
s):
97%
T
(
EPA
Reg.
No.
66222­
78)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
N
830.1600
Description
of
materials
used
to
produce
the
product
N
830.1620
Description
of
production
process
N
830.1670
Discussion
of
formation
of
impurities
N
830.1700
Preliminary
analysis
N
830.1750
Certified
limits
N
830.1800
Enforcement
analytical
method
N
830.6302
Color
N
830.6303
Physical
state
N
830.6304
Odor
N
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
N
830.6314
Oxidation/
reduction:
chemical
incompatibility
N
830.6315
Flammability
N/
A
830.6316
Explodability
N
830.6317
Storage
stability
N
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
N
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
N
830.7050
UV/
visible
absorption
N
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
N
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
N
830.7370
Dissociation
constant
N
830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
N
830.7840/
7860Water
solubility
N
830.7950
Vapor
pressure
N
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
16
17
Case
No.
0196
Chemical
No.
030801
Case
Name:
2,4­
DB
Registrant:
Makhteshim­
Agan
of
North
America
Product(
s):
75%
T
(
EPA
Reg.
No.
66222­
80;
transferred
from
Cedar
Chemical
Co
2/
3/
03,
EPA
Reg.
No.
56077­
85
for
which
data
below
were
generated)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
Y
b
830.1600
Description
of
materials
used
to
produce
the
product
Y
b
830.1620
Description
of
production
process
Y
b
830.1670
Discussion
of
formation
of
impurities
Y
b
830.1700
Preliminary
analysis
Y
b
830.1750
Certified
limits
N
830.1800
Enforcement
analytical
method
Y
b
830.6302
Color
Y
830.6303
Physical
state
Y
b
830.6304
Odor
Y
b
830.6313
Stability
to
normal
and
elevated
temperatures,
metals,
and
metal
ions
Y
b
830.6314
Oxidation/
reduction:
chemical
incompatibility
Y
b
830.6315
Flammability
N/
A
830.6316
Explodability
Y
b
830.6317
Storage
stability
Y
b
830.6319
Miscibility
N/
A
830.6320
Corrosion
characteristics
Y
b
830.6321
Dielectric
breakdown
voltage
N/
A
830.7000
pH
Y
b
830.7050
UV/
visible
absorption
Y
b
830.7100
Viscosity
N/
A
830.7200
Melting
point/
melting
range
Y
b
830.7220
Boiling
point/
boiling
range
N/
A
830.7300
Density/
relative
density/
bulk
density
Y
b
830.7370
Dissociation
constant
Y
b
830.7550/
7560
/
7570
Partition
coefficient
(
n­
octanol/
water)
Y
b
830.7840/
7860Water
solubility
Y
b
830.7950
Vapor
pressure
Y
b
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
18
b
MRID
No.
431192;
Shyam
B.
Mathus
review,
3/
28/
94.

Case
No.
0196
Chemical
No.
030819
Case
Name:
2,4­
DB
DMA
Registrant:
A.
H.
Marks
&
Co.
Ltd
Product(
s):
49.2%
FI
(
EPA
Reg.
No.
15440­
33)

PRODUCT
CHEMISTRY
DATA
SUMMARY
Guideline
Number
Requirement
Requirement
Fulfilled?
a
Reference
830.1550
Product
identity
and
composition
Y
439695­
01
830.1600
Description
of
materials
used
to
produce
the
product
Y
439695­
01
830.1620
Description
of
production
process
Y
439695­
01
830.1670
Discussion
of
formation
of
impurities
Y
439695­
01
830.1700
Preliminary
analysis
Y
439695­
05
830.1750
Certified
limits
Y
439695­
01
830.1800
Enforcement
analytical
method
Y
439695­
05
830.6302
Color
N
830.6303
Physical
state
Y
439695­
04
830.6304
Odor
N
830.6314
Oxidation/
reduction:
chemical
incompatibility
Y
439695­
04
830.6316
Explodability
Y
439695­
04
830.6317
Storage
stability
N
830.6320
Corrosion
characteristics
Y
439695­
04
830.7000
pH
N
830.7100
Viscosity
Y
439695­
04
830.7300
Density/
relative
density/
bulk
density
Y
439695­
04
a
Y
=
Yes;
N
=
No;
N/
A
=
Not
Applicable.
19
AGENCY
MEMORANDA
CITED
IN
THIS
DOCUMENT
CBRS
No(
s).:
None
DP
Barcode:
D218938
Subject:
2,4­
DB
Review
of
Product
Chemistry
GDLNs
63­
14,
63­
16,
63­
17,
and
63­
20.
From:
D.
Miller
To:
J.
Coombs
Dated:
2/
23/
96
MRID(
s):
None
CBRS
No(
s).:
14501
DP
Barcode:
D208171
Subject:
Protocol
for
the
Determination
of
Chlorinated
Dioxins
and
Dibenzofurans
From:
S.
Funk,
PhD.
To:
Walter
Waldrop
Dated:
11/
30/
94
MRID(
s):
None
CBRS
No(
s).:
13056
DP
Barcode:
D198007
Subject:
Task
Force
Response
Regarding
Dissociation
Constant
for
2,4­
DB
DMA
Salt
From:
Freshteh
Toghrol,
Ph.
D.
To:
Walter
Waldrop
Dated:
10/
6/
94
MRID(
s):
None
CBRS
No(
s).:
13157
DP
Barcode:
D198970
Subject:
A.
H.
Marks:
Product
Chemistry
Data
for
Reregistration
Purposes
and
to
Support
registration
of
Their
Pending
96%
T.
From:
Freshteh
Toghrol,
Ph.
D.
To:
Joanne
Miller
and
Walter
Waldrop
Dated:
9/
30/
94
MRID(
s):
43095501
CBRS
No(
s).:
11288
DP
Barcode(
s):
D187428
Subject:
Cedar
Chemical
Corporation
97%
Technical
From:
P.
Deschamp
To:
J.
Coombs
Dated:
4/
8/
93
MRID(
s):
42626501
CBRS
No(
s).:
11046
DP
Barcode(
s):
D185750
Subject:
Reregistration
of
2,4­
DB
DMA
Salt.
Additional
Vapor
Pressure
Information
In
Response
to
S.
Knizner's
8/
20/
92
Review.
From:
K.
Dockter
To:
Walter
Waldrop
and
J.
Coombs
20
Dated:
2/
9/
93
MRID(
s):
425693­
01,
­
04
CBRS
No(
s).:
10280
DP
Barcode(
s):
D180984
Subject:
Vapor
Pressure
Determination
of
2,4­
DB
Dimethylamine
Salt
From:
Steven
A.
Knizner
To:
J.
Coombs
Dated:
8/
20/
92
MRID(
s):
None
CBRS
No(
s).:
10241
DP
Barcode(
s):
D180796
Subject:
2,4­
DB
Dimethylamine
Salt
Reregistration.
Product
Chemistry
Guideline
63­
7
From:
A.
Aikens
To:
W.
Waldrop
and
J.
Coombs
Dated:
8/
7/
92
MRID(
s):
None
CBRS
No(
s).:
8909
DP
Barcode(
s):
D170669
Subject:
Reregistration
of
2,4­
DB.
Task
Force
Response
to
Registration
Standard
for
Product
Chemistry:
Boiling
Point;
Density.
From:
Stephen
Funk,
Ph.
D.
To:
J.
Coombs
Dated:
6/
23/
92
MRID(
s):
415829­
01,
­
02
CBRS
No(
s).:
9696
DP
Barcode:
D176603
Subject:
Determination
of
Polychlorinated
Dibenzi­
p­
dioxins
and
Dibenzofurans
in
A.
H.
Marks
Technical
2,4­
DB.
From:
S.
Funk,
PhD.
To:
J.
Coombs
Dated:
6/
3/
92
MRID(
s):
None
CBRS
No(
s).:
9561
DP
Barcode:
D175442
Subject:
Determination
of
Polychlorinated
Dibenzi­
p­
dioxins
and
Dibenzofurans
in
Cedar
Chemical
Company
Technical
2,4­
DB.
From:
S.
Funk,
Ph.
D.
To:
J.
Coombs
Dated:
6/
3/
92
MRID(
s):
None
CBRS
No(
s).:
9364
DP
Barcode:
D174121
Subject:
Waiver
Request
from
the
2,4­
DB
Task
Force
concerning
a
vapor
pressure
study
for
the
dimethylamine
salt
of
2,4­
DB.
From:
Dennis
McNeilly
To:
J.
Coombs
Dated:
3/
6/
92
MRID(
s):
None
CBRS
No(
s).:
9068
DP
Barcode(
s):
D172238
Subject:
Determination
of
Polychlorinated
Dibenzi­
p­
dioxins
and
Dibenzofurans
in
Technical
2,4­
DB.
21
From:
Stephen
Funk,
Ph.
D.
To:
J.
Coombs
Dated:
1/
13/
92
MRID(
s):
421029­
00,
­
01;
418008­
01,
­
02;
420653­
01
through
­
08.

CBRS
No(
s).:
8615
DP
Barcode(
s):
D161185
Subject:
Analysis
of
technical
2,4­
DB
Acid
for
Polychlorinated
Dibenzi­
p­
dioxins
and
Dibenzofurans.
Response
to
DCI.
From:
S.
Funk,
Ph.
D.
To:
E.
Ferris
Dated:
10/
31/
91
MRID(
s):
417655­
00,
­
01
CBRS
No(
s).:
7698
DP
Barcode(
s):
D161375
Subject:
A.
H.
Marks
Response
to
the
2,4­
DB
Registration
Standard:
Product
Chemistry
From:
Fresteh
Toghrol,
Ph.
D.
To:
L.
Rossi
/
J.
Coombs;
Reto
Engler
Dated:
7/
9/
91
MRID(
s):
411482­
01
CBRS
No(
s).:
6822
Subject:
2,4­
DBTechnical
Acid
­
Reregistration
Standard
­
Response
of
the
2,4­
DB
Task
Force
to
the
Product
Chemistry
Chapter
From:
G.
Makhijani
To:
J.
Coombs
Dated:
8/
9/
90
MRID(
s):
413814­
02
CBRS
No(
s).:
6823
Subject:
2,4­
DB
Product
Chemistry
Data
­
Physical
and
Chemical
Characteristics
From:
G.
Makhijani
To:
J.
Coombs
Dated:
8/
3/
90
MRID(
s):
415170­
01
through
­
04
CBRS
No(
s).:
6555
Subject:
2,4­
DB
Registration
Standard
Response
to
Product
Chemistry
Data
Requirements.
From:
H.
Fonouni
To:
J.
Coombs
and
R.
Engler
Dated:
4/
26/
90
MRID(
s):
414022­
01
through
­
16;
413749­
01
CBRS
No(
s).:
6626
Subject:
Product
Chemistry
data
­
2,4­
DB
Dimethylamine
salt
­
2,4­
DB
Task
Force
From:
G.
Makhijani
To:
J.
Coombs
Dated:
5/
25/
90
MRID(
s):
414604­
01
CBRS
No(
s).:
6330
Subject:
Data
Call­
In
Notice
for
Analytical
Chemistry
Data
on
Polyhalogenated
Dibenzo­
p­
dioxins
and
Dibenzofurans.
From:
S.
Funk,
PhD.
To:
E.
Feris
Dated:
6/
13/
90
22
MRID(
s):
413185­
01
through
­
03.

CBRS
No(
s).:
3732
Subject:
Aceto
response
Regarding
Analysis
of
2,4­
DB
for
TCDD
From:
R.
Loranger,
Ph.
D.
To:
G.
Werdig
/
F.
Rubis
Dated:
7/
15/
88
MRID(
s):
None
CBRS
No(
s).:
6367
Subject:
Product
Chemistry
Data
for
Aceto
DB
175
(
2,4­
DB
Dimethylamine
Salt)
From:
S.
Funk,
Ph.
D.
To:
E.
Feris
Dated:
3/
13/
90
MRID(
s):
408179­
01
CBRS
No(
s).:
5665
Subject:
Polyhalogenated
Dibenzo­
p­
dioxins
/
Dibenzofurans
Data
Call­
In
Notice
From:
F.
Griffith
To:
C.
Grubbs
/
V
Prunier
Dated:
9/
19/
89
MRID(
s):
None
CBRS
No(
s).:
2704
Subject:
Additional
Product
Chemistry
Data
for
Union
Carbide's
Technical
2,4­
DB
From:
Richard
Loranger,
Ph.
D.
To:
S.
Lewis
/
G.
Werdig
Dated:
9/
29/
87
MRID(
s):
402959­
01,
­
02,
­
03.

CBRS
No(
s).:
587,
591
Subject:
product
Chemistry
and
Similarity
of
2,4­
DB
technicals
From:
R.
Loranger,
Ph.
D.
To:
G.
Werdig
/
S.
Lewis
Dated:
3/
13/
86
MRID(
s):
Accession
No.
259904
CBRS
No(
s).:
None
Subject:
Addendum
to
3/
13/
86
review
on
similarity
of
2,4­
DB
technicals
From:
R.
Loranger,
Ph.
D.
To:
G.
Werdig
/
S.
Lewis
Dated:
6/
30/
86
MRID(
s):
None
CBRS
No(
s).:
None
Subject:
2,4­
DB
Registration
Standard
From:
C
Trichilo,
Ph.
D.
To:
A.
Rispin
/
R.
Mountfort
Dated:
2/
1/
88
CBRS
No(
s).:
RD
Review
DP
Barcode:
D286840
Subject:
Product
Chemistry
review
of
a
Technical
Grade
of
Active
Ingredient,
New
Manufacturing
Process
of
a
Registered
Chemical,
Food/
Feed
Uses
From:
S.
Malak,
Ph.
D.
To:
J.
Miller
/
Diane
Morgan
Dated:
1/
9/
03
23
MRID(
s):
455969­
01
through
­
04.

CBRS
No(
s).:
RD
Review
DP
Barcode:
D286249
Subject:
Product
Chemistry
Review
of
Technical
,4­
DB
From:
S.
Mathur
To:
J.
Miller
/
J.
Stone
Dated:
1/
22/
03
MRID(
s):
457701­
01
through
­
05
CBRS
No(
s).:
RD
Review
Subject:
Product
Chemistry
review
for
End
Use
Product
From:
S.
Mathur
To:
J.
Miller
/
Diane
Morgan
Dated:
3/
28/
94
MRID(
s):
432192­
01
RESIDUE
CHEMISTRY
CONSIDERATIONS
(
PC
Codes
030801,
030819)

(
DP
Barcode
No.
D291212)

A.
INTRODUCTION
Background
2,4­
DB
[
4­(
2,4­
dichlorophenoxy)
butyric
acid]
is
a
plant
growth
regulator
and
herbicide
registered
for
use
on
alfalfa,
clover,
peanuts,
soybean,
peppermint,
spearmint,
and
trefoil.
It
is
currently
marketed
as
the
acid
(
030801)
and
the
dimethylamine
salt
(
030819);
no
other
salt
or
ester
products
are
currently
registered.
End
Use
products
are
formulated
either
as
soluble,
emulsifiable,
or
flowable
concentrates
(
SC/
L,
EC,
or
FlC).
2,4­
DB
can
be
applied
either
as
a
broadcast
application
early
season,
or
a
directed
spray
late
season.
Ground
or
aerial
applications
may
be
made.

Tolerances
for
residues
of
2,4­
DB
in
plant
commodities
are
currently
expressed
as
the
combined
residues
of
the
herbicide
(
4­(
2,4­
dichlorophenoxy)
butyric
acid
and
its
metabolite
2,4­
dichlorophenoxyacetic
acid
(
2,4­
D).
Current
tolerance
levels
are
set
at
0.2
ppm
residues
in
all
crops.
Neither
tolerances
for
livestock
commodities
nor
food/
feed
tolerances
for
processed
commodities
have
been
established.

2,4­
DB
was
the
subject
of
a
Reregistration
Standard
Guidance
Document
dated
2/
88.
The
information
contained
in
this
document
outlines
the
Residue
Chemistry
Science
Assessments
with
respect
to
the
reregistration
of
2,4­
DB.
24
O
Cl
Cl
O
OH
TABLE
1.
2,4­
DB
Nomenclature
Compound
Chemical
Structure
Common
name
2,4­
DB
Company
code
number
None
specified
IUPAC
name
4­(
2,4­
dichlorophenoxy)
butyric
acid
Chemical
abstract
name
4­(
2,4­
dichlorophenoxy)
butanoic
acid
CAS
registry
number
94­
82­
6
TABLE
2.
Physicochemical
Properties
of
the
Technical
Grade
of
2,4­
DB
Parameter
Value
Reference
Melting
point/
range
113.5­
117.5

C
D198970,
9/
30/
94,
F.
Toghrol
pH
(
20

C)
4.31
(
1%
w:
v)
D198970,
9/
30/
94,
F.
Toghrol
Density
(
22

C)
1.461
D198970,
9/
30/
94,
F.
Toghrol
Water
solubility
(
25

C)
46
ppm
D161375,
7/
9/
91,
F.
Toghrol
Solvent
solubility
(
25

C)
100
g/
L
in
acetone
50
g/
L
in
ethanol
D161375,
7/
9/
91,
F.
Toghrol
Vapor
pressure
7.1
x
10­
7
mm
Hg
at
23.6

C
DEB
No.
6823,
8/
3/
90,
G.
Makhijani
Dissociation
constant,
pKa
2.99
x
10­
5
DEB
No.
6823,
8/
3/
90,
G.
Makhijani
Octanol/
water
partition
coefficient,
Log(
KOW)
2.62
DEB
No.
6823,
8/
3/
90,
G.
Makhijani
UV/
visible
absorption
spectrum
Three
distinct
bands
at
202,
229,
and
284
nm;
no
appreciable
differences
in
the
extinction
coefficients
between
acidic,
neutral,
and
basic
solutions.
D286840,
1/
9/
03,
S.
Malak
860.1200
Directions
for
Use
An
OPPIN
search
conducted
7/
9/
03
indicated
that
there
are
14
end­
use
products
(
EPs)
of
2,4­
DB
that
may
be
used
on
food/
feed
crops
grown
in
the
U.
S.
(
Table
3).
There
are
four
Special
Local
Need
(
SLN)
registrations
under
FIFRA
Section
24.

Table
3.
2
,4­
DB
End­
Use
Products
with
Food/
Feed
Uses
EPA
Reg.
No.
Percent1
lbs
a.
e/
gal
Formulation
Type
Label
Date
a.
i.
a.
e.

2,4­
DB
Dimethylamine
Salt
Products
(
030819)

Aceto
Agricultural
Chemicals
Corp.
EPA
Reg.
No.
Percent1
lbs
a.
e/
gal
Formulation
Type
Label
Date
a.
i.
a.
e.

25
2749­
126
23
19.5
1.75
SC/
L
3/
17/
94
2749­
516
25.9
21.9
2
SC/
L
9/
9/
94
A.
H.
Marks
&
Co.
LTD
15440­
32
26.85
22.6
2
EC
9/
16/
96
15440­
34
23.7
19.8
1.75
SC/
L
7/
29/
97
Albaugh
Inc
42750­
38
25.9
22.0
2
SC/
L
1/
9/
03
42750­
39
23.0
19.5
1.75
SC/
L
3/
20/
03
Micro­
Flo
Co.
LLC
51036­
231
23.0
19.5
1.75
FlC
2/
9/
95
51036­
232
25.9
22.0
2
SC/
L
2/
9/
95
Makhteshim­
Agan
of
North
America
Inc
66222­
76
26.2
22.0
2
SC/
L
4/
30/
86
66222­
77
23.0
19.5
1.75
SC/
L
4/
5/
02
66222­
79
23.0
19.5
1.75
SC/
L
4/
30/
86
Nu­
Farm
Inc
71368­
32
23.0
19.5
1.75
SC/
L
1/
28/
02
71368­
33
25.9
21.9
2
SC/
L
1/
28/
02
2,4­
DB
Acid
Products
(
030801)

Makhteshim­
Agan
of
North
America
Inc
66222­
80
75
­
­
SC/
L
2/
13/
96
1a.
e.
=
percent
acid
equivalent,
a.
i.
=
percent
active
ingredient
(
dimethylamine
salt
of
2,4­
DB)

A
comprehensive
summary
of
the
registered
food/
feed
use
patterns
of
2,4­
DB,
based
on
these
product
labels,
is
presented
in
Table
4.

Information
provided
by
the
Biological
and
Economic
Analysis
Division
(
BEAD,
Alan
Halvorson,
10/
31/
01)
indicates
that
2,4­
DB
is
typically
applied
at
rates
significantly
less
than
the
maximum
label
rate.
Typically
only
one
application
is
made
to
a
crop
each
year
except
in
Conservation
Reserve
Program
Areas
where
an
average
of
1.2
applications
per
year
are
made.
The
percent
of
crop
treated
is
significantly
less
than
10%
for
all
crops
except
peanuts
for
which
38%
crop
treated
is
estimated.
26
Table
4.
2,4­
DB
Food/
Feed
Use
Patterns
Crop
Maximum
Single
Application
Rate1
Maximum
Number
Application
s
Minimum
Application
Interval
(
Days)
PHI2
(
Days)
PGI3
(
Days)
lbs
ae/
A
lbs
ai/
A
Alfalfa,
seedling
1.3
1.5
1
NA4
60
60
Alfalfa,
established
1.3
1.5
1
NA4
30
30
Birdsfoot
trefoil,
seedling
only
1.3
1.5
1
NA4
NA
60
Clover,
seedling
1.3
1.5
1
NA4
NS5
60
Soybeans,
postemergence
broadcast
0.19
0.22
NS5
NS5
60
60
Soybeans,
postemergence
directed
spray
0.34
0.4
2
NS5
60
60
Peanuts
(
specified
states
in
SE
U.
S.)
0.22
0.25
2
NS5
45
FR6
Peanuts
(
specified
states
in
SW
U.
S.)
0.34
0.4
2
14
30
FR6
CRPA7
1.3
1.5
NS5
NS5
Do
not
graze
or
feed
treated
crops
Peppermint/
spearmint
(
ID94001000
WA94002700
MT95000500
OR94001500)
0.64
0.75
NS5
NS5
90
NA4
1lbs
ae/
A
=
lbs.
acid
equivalent/
A;
lbs
ai/
A
=
lbs
active
ingredient/
A
2PHI
=
Pre­
harvest
Interval
3PGI
=
Pre­
grazing
Interval
4NA
=
Not
Applicable
to
this
use
5NS
=
Not
Specified
6FR
=
feeding
restriction
for
vines
and
hay
7CRPA
=
Conservation
Reserve
Program
Areas
860.1300
Nature
of
the
Residue­
Plants
DER
Reference
List:
42965901(
alfalfa),
43033901
(
peanut),
43033803
(
soybean).
Metabolism
Committee
Decision
Memos:
5/
11/
94
Greybeard
Committee
Decision;
D.
Miller,
D220888,
11/
14/
95;
D.
Miller,
D221954,
1/
29/
96.

The
qualitative
nature
of
the
2,4­
DB
residue
in
plant
commodities
is
adequately
understood
based
on
acceptable
metabolism
studies
in
alfalfa,
peanuts
and
soybeans.
27
2,4­
DB
is
metabolized
in
several
ways
including
side­
chain
degradation
[
to
form
2,4­
dichlorophenoxyacetic
acid
(
2,4­
D)
and
related
products],
ring
hydroxylation,
position
shift
of
the
chlorine
atoms
on
the
ring,
and
dechlorination.
Incorporation
of
radioactivity
into
sugar,
protein,
and
other
natural
constituents
also
resulted
from
metabolism
of
the
ring­
labeled
compound.
1,4­
benzoquinone
is
a
major
metabolite
in
soybean
hay,
pods,
and
vines.
However,
the
parent
is
the
primary
residue
found
in
most
crop
matrices.

The
HED
Metabolism
Committee
(
D.
Miller,
11/
14/
95
and
1/
29/
96)
concluded
that
the
residue
to
be
regulated
in
plants
is
2,4­
DB
per
se,
and
that
2,4­
D
need
not
be
included
in
the
tolerance
expression.
1,4­
benzoquinone
was
to
be
excluded
from
the
tolerance
expression
because
it
is
significant
only
in
certain
animal
feeds,
and
other
residues
were
excluded
because
they
each
comprise
only
a
small
portion
of
the
total
residue.
(
MRID
Nos.
429659­
01,
430338­
01,
430338­
03,
430339­
01).
If
additional
crops
with
direct
human
consumption
are
registered,
additional
metabolism
studies
may
be
required.

Plant
metabolism
studies
for
2,4­
DB
utilized
the
acid
form
(
030801).
The
Agency
granted
a
waiver
(
5/
11/
94
Greybeard
Committee
memorandum)
for
metabolism
studies
for
the
DMA
salt
concluding
that
studies
for
the
acid
will
suffice
to
characterize
metabolism
for
both
the
salt
and
the
acid.

860.1300
Nature
of
the
Residue
­
Livestock
DER
Reference
List:
43009801
(
hen),
43033802
(
goat).
Metabolism
Committee
Decision
Memos:
5/
11/
94
Greybeard
Committee
Decision;
D.
Miller,
D220888,
11/
14/
95;
D.
Miller,
D221954,
1/
29/
96.

The
qualitative
nature
of
the
residue
in
ruminants
and
poultry
is
adequately
understood
based
on
adequate
studies
in
dairy
cows
and
laying
hens.
In
the
hen
study,
the
highest
radioactivity
was
found
in
eggs,
fat,
and
liver.
Most
of
the
residue
was
identified
as
the
unchanged
parent
compound.
In
dairy
cows,
the
highest
radioactivity
was
found
in
milk,
liver,
and
kidney;
residues
in
muscle
and
fat
were
very
low.
Metabolites
included
the
glycine
conjugate
of
2,4­
DB,
2,4­
DB
per
se,
and
2,4­
dichlorophenol.

Based
on
these
data,
the
HED
Metabolism
Committee
(
D.
Miller,
11/
14/
95
and
1/
29/
96)
concluded
that
the
residue
to
be
regulated
in
meat,
milk,
poultry
and
eggs
is
2,4­
DB
per
se,
and
that
2,4­
D
need
not
be
included
in
the
tolerance
expression.
Other
metabolites
were
excluded
due
to
either
lower
potential
for
toxicity
or
relatively
insignificant
residue
levels.

Livestock
metabolism
studies
for
2,4­
DB
utilized
the
parent
compound
(
acid,
030801).
The
Agency
granted
a
waiver
(
5/
11/
94
Greybeard
Committee
memorandum)
for
metabolism
studies
for
the
DMA
salt
concluding
that
studies
for
the
acid
will
suffice
to
characterize
metabolism
for
both
the
salt
and
the
acid.

860.1340
Residue
Analytical
Methods
DER
Reference
List:
43033801,
43358601,43201701
(
soybean);
43121801
(
alfalfa);
43393301(
peanuts);
44334704,
44546301,
44997901
(
livestock
commodities).
28
The
Pesticide
Analytical
Manual
(
PAM)
Vol.
II,
lists
Method
I,
a
GC
method
with
microcoulometric
detection,
for
the
enforcement
of
tolerances
for
2,4­
DB
residues;
this
method
is
the
PAM
Vol.
I
method
for
chlorophenoxy
acid
residues
in
food.

Residue
Analytical
Methods
­
Plants
Soybean
Seed,
Forage,
Hay,
and
Straw
The
2,4­
DB
Task
Force
submitted
descriptions
of
and
recovery
data
for
a
GC
analytical
method
with
electron­
capture
detection
(
GC/
ECD)
for
determining
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
soybean
seed,
forage,
hay,
and
straw
(
1993,
MRID
43033801).

Residues
in
soybean
matrices
are
extracted
twice
by
homogenization
with
acidified
acetonitrile
(
ACN,
containing
1.5%
phosphoric
acid)
and
centrifuged.
The
ACN
extracts
are
combined,
mixed
with
deionized
water,
and
readjusted
to
pH
2
with
HCl:
water
(
1:
1,
v:
v),
if
necessary.
The
aqueous
extract
is
then
partitioned
three
times
with
ethyl
ether.
The
resulting
ether
fractions
are
combined
and
partitioned
four
times
with
water
adjusted
to
pH
11
with
sodium
hydroxide;
saturated
NaCl
may
be
added
to
inhibit
emulsion
formation.
The
aqueous
fractions
are
combined,
placed
under
a
nitrogen
stream
to
evaporate
traces
of
ether,
and
readjusted
to
pH
2
with
HCl:
water
(
1:
1,
v:
v).
The
acidified
aqueous
extract
is
then
applied
to
C18
and
C8
solid
phase
extraction
(
SPE)
columns
arranged
in
series.
The
columns
are
preconditioned
with
dichloromethane,
methyl­
tert­
butyl
ether
(
MTBE),
ACN,
and
acidified
water
(
pH
2)
under
a
vacuum.
Residues
of
interest
are
eluted
from
the
columns
with
MTBE
under
positive
pressure.
The
collected
eluant
is
washed
twice
with
MTBE
and
the
organic
and
aqueous
phases
are
allowed
to
separate.
The
organic
phases
are
combined,
mixed
with
a
small
amount
of
mineral
oil
to
serve
as
a
keeper,
and
concentrated
under
a
nitrogen
stream.
At
this
step,
an
aliquot
is
removed
for
analysis
for
2,4­
D
phenol
by
GC/
ECD
using
a
Stabilwax
column.

The
remainder
of
the
concentrated
sample
is
mixed
with
diazomethane
in
ether
and
applied
to
an
alumina
column
preconditioned
with
hexane.
The
derivatized
residues
are
then
eluted
from
the
column
with
hexane
and
mixed
with
a
small
amount
of
isooctane
as
a
keeper.
The
eluant
is
then
concentrated
by
rotary
evaporation,
mixed
with
hexane.
After
concentration
under
a
nitrogen
stream,
the
sample
is
analyzed
for
2,4­
DB
and
2,4­
D
by
GC/
ECD
using
a
DB­
1
column.
The
limit
of
detection
is
0.01
ppm
and
the
limit
of
quantitation
is
0.05
ppm
for
the
parent
and
each
metabolite
in
the
four
soybean
matrices.

Recoveries
of
2,4­
DB
less
than
70%
were
obtained
at
all
fortification
levels
in
all
commodities
except
soybean
straw;
recoveries
were
55.8­
104.8%
from
soybean
seed,
71.5­
101.3%
from
soybean
straw,
48.7­
106.7%
from
soybean
hay,
and
49.2­
100.5%
from
soybean
forage,
each
fortified
at
0.05­
0.40
ppm.
Although
it
was
determined
by
the
HED
Metabolism
Committee
that
residues
of
2,4­
D
will
not
be
regulated,
recoveries
of
2,4­
D
were
variable;
49.4­
130.7%
from
soybean
seed,
71.5­
146.2%
from
soybean
straw,
43.7­
167.9%
from
soybean
hay,
and
51.2­
148.9%
from
soybean
forage
fortified
at
0.05­
0.40
ppm.
Recoveries
of
2,4­
D
phenol
(
also
not
to
be
regulated)
were
adequate,
with
some
high
recoveries,
in
soybean
seed
(
72.0­
122.8%),
soybean
straw
(
71.1­
163.8%),
soybean
hay
(
65.5­
149.7%),
and
soybean
forage
(
61.0­
110.0%)
fortified
at
0.05­
0.40
ppm.
29
The
method
recovery
data
indicate
that
the
submitted
GC/
ECD
method
for
the
determination
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
soybean
commodities
is
marginally
adequate
for
data
collection.
The
submitted
method
may
be
used
for
data
collection
purposes
but
the
method
must
be
adequately
validated
for
each
study
for
which
it
is
used.

The
2,4­
DB
Task
Force
has
also
submitted
(
1994;
MRID
43358601)
an
amendment
to
a
previously
submitted
GC/
ECD
method
for
the
determination
of
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in/
on
soybean
commodities.
The
report
of
the
amended
method
includes
a
list
of
all
modifications
made
to
the
method.
All
of
the
modifications
are
minor,
and
most
were
made
to
correct
small
errors
or
to
improve
the
clarity
of
the
method
instructions.
No
new
validation
data
were
submitted
with
the
amended
method.
Therefore,
the
conclusions
specified
in
the
review
of
the
original
method
submission
remain
the
same.

Alfalfa
Forage
and
Hay
and
Soybean
Processed
Commodities
The
2,4­
DB
Task
Force
has
submitted
descriptions
of
and
validation
data
for
residue
analytical
methods
for
the
determination
of
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
alfalfa
forage
and
hay
(
1994;
MRID
43121801)
and
soybean
meal,
hulls,
soapstock,
crude
oil,
and
refined
oil
(
1994,
MRID
43201701).

Alfalfa
and
soybean
matrices
(
except
crude
and
refined
oil)
are
homogenized
twice
with
acidified
acetonitrile
(
ACN;
containing
1.5%
phosphoric
acid)
and
centrifuged;
soybean
soapstock
is
mixed
with
celite
prior
to
homogenization
to
prevent
the
sample
from
sticking
to
the
glass.
The
ACN
extracts
are
combined,
mixed
with
deionized
water,
and
readjusted
to
pH
2
with
HCl:
water
(
1:
1,
v:
v),
if
necessary.
The
ACN:
water
extract
is
then
partitioned
three
times
with
ethyl
ether.
The
resulting
ether
fractions
are
combined
and
partitioned
four
times
with
water
(
adjusted
to
pH
11
with
sodium
hydroxide);
if
an
emulsion
forms,
saturated
sodium
chloride
is
added.
The
aqueous
fractions
are
combined,
placed
under
a
stream
of
nitrogen
to
remove
traces
of
ether,
and
readjusted
to
pH
2
with
HCl:
water
(
1:
1,
v:
v).
Soybean
crude
and
refined
oil
samples
are
dissolved
in
hexane
and
partitioned
four
times
with
1%
aqueous
sodium
hydroxide
(
freshly
prepared);
if
an
emulsion
forms,
saturated
sodium
chloride
is
added.
The
pH
of
the
aqueous
fraction
is
adjusted
to
pH
2
with
HCl:
water
(
1:
1,
v:
v).
The
acidified
aqueous
extract
(
all
matrices)
is
then
applied
to
C18
and
C8
solid
phase
extraction
(
SPE)
columns
arranged
in
series.
The
columns
are
sequentially
preconditioned
with
dichloromethane,
methyl­
tert­
butyl
ether
(
MTBE),
ACN,
and
acidified
water
(
pH
2)
under
vacuum.
Residues
of
interest
are
eluted
from
the
SPE
columns
with
MTBE
under
positive
pressure.
The
collected
eluant
containing
MTBE
and
water
is
washed
twice
with
MTBE,
and
the
organic
and
aqueous
phases
are
allowed
to
separate.
The
organic
fractions
are
combined,
mixed
with
a
small
amount
of
mineral
oil,
and
concentrated
under
a
nitrogen
stream.
At
this
step,
an
aliquot
is
removed
for
analysis
of
2,4­
D
phenol
by
GC/
ECD
using
a
Stabilwax
column.

The
remainder
of
the
concentrated
MTBE
extract
is
mixed
with
diazomethane
in
ether
and
applied
to
an
alumina
column
preconditioned
with
hexane.
The
derivatized
residues
are
then
eluted
from
the
column
with
hexane
and
mixed
with
0.5
mL
of
isooctane.
Derivatized
extracts
of
soybean
meal,
hulls,
and
crude
and
refined
oil
do
not
undergo
the
alumina
column
cleanup
step.
The
eluant/
derivatized
extract
is
concentrated
by
rotary
evaporation,
mixed
with
hexane,
and
then
30
concentrated
under
a
nitrogen
stream.
The
concentrated
residues
are
analyzed
for
2,4­
DB
and
2,4­
D
by
GC/
ECD
using
a
DB­
1
column.
The
registrant
reported
the
following
limits
of
detection:
0.013
ppm
for
2,4­
DB
and
2,4­
D
in
alfalfa
forage
and
hay;
0.067
ppm
for
2,4­
DB
and
2,4­
D
in
soybean
processed
commodities;
and
0.02
ppm
for
2,4­
D
phenol
in
each
matrix.
The
limit
of
quantitation
was
reported
to
be
0.05
ppm
for
the
parent
and
each
metabolite
in
each
matrix.
However,
the
data
suggest
that
the
limit
of
quantitation
is
more
nearly
0.2
ppm
as
unreliable
recoveries
were
consistently
seen
in
samples
fortified
at
lower
levels.

The
method
recovery
data
indicate
that
the
submitted
GC/
ECD
method
for
the
determination
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
alfalfa
forage
and
hay
is
marginally
adequate
for
data
collection.
Recoveries
of
each
analyte,
from
samples
fortified
at
0.05­
0.40
ppm,
were
variable.
Recoveries
less
than
70%
were
observed
for
each
analyte
in
both
forage
and
hay,
and
recoveries
greater
than
120%
were
observed
for
2,4­
DB
and
2,4­
D
phenol
in
forage
and
hay.
Acceptable
recoveries
of
2,4­
DB
were
obtained
from
16
of
23
forage
samples
and
12
of
16
hay
samples.
Per
an
HED
Metabolism
Committee
decision,
2,4­
D
and
2,4­
D
phenol
are
not
residues
of
concern,
thus
the
recoveries
calculated
by
the
registrant
for
these
metabolites
are
not
relevant.

The
method
recovery
data
indicate
that
the
submitted
GC/
ECD
method
for
the
determination
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
soybean
processed
commodities
is
marginally
adequate
for
data
collection.
Recoveries
of
each
analyte,
from
samples
fortified
at
0.05­
0.40
ppm,
were
variable.
Recoveries
less
than
70%
were
observed
for
each
analyte
in
each
commodity
(
except
2,4­
D
in
hulls),
and
recoveries
greater
than
120%
were
observed
for
2,4­
DB
and
2,4­
D
in
meal,
hulls,
and
refined
oil,
and
for
2,4­
D
phenol
in
meal
and
hulls.
Acceptable
recoveries
of
2,4­
DB
were
obtained
from
9
of
19
meal
samples,
13
of
19
hull
samples,
8
of
11
soapstock
samples,
21
of
25
crude
oil
samples,
and
22
of
28
refined
oil
samples.
Because
2,4­
D
and
2,4­
D
Phenol
are
not
residues
of
concern,
the
recoveries
calculated
for
these
metabolites
are
not
relevant.

Peanut
2,4­
DB
Task
Force
submitted
analytical
methods
for
determining
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in
peanut
nutmeat,
hulls,
vines
and
hay
(
1994;
MRID
43393301).
The
peanut
method
is
essentially
identical
to
the
method
described
above
for
soybean
seed,
forage,
hay,
and
straw
(
MRID
43033801).

The
submitted
GC/
ECD
method
is
adequate
for
collecting
data
on
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
D
phenol
in/
on
peanut.
The
HED
Metabolism
Committee
has
concluded
that
2,4­
D
and
2,4­
D
phenol
are
not
residues
of
concern;
therefore,
the
recoveries
calculated
by
the
registrant
for
these
metabolites
are
not
relevant
at
this
time.
Method
recoveries
of
2,4­
DB
from
the
regulated
commodities
peanut
and
peanut
hay
fortified
at
0.05
ppm
were
91%
to
169%
(
one
of
six
fortified
samples
above
120%).
The
validated
limit
of
quantitation
(
LOQ)
of
2,4­
DB
in/
on
peanut
matrices
is
0.05
ppm.

Conclusions.
The
submitted
plant
analytical
methods
are
adequate
for
data
collection
but
must
be
adequately
validated
for
each
study
for
which
it
is
used.
If
any
of
the
above
analytical
methods
for
plant
commodities
are
proposed
as
a
2,4­
DB
tolerance
enforcement
method,
independent
laboratory
validation
should
be
performed.
31
Residue
Analytical
Methods
­
Livestock
Ruminant
The
2,4­
DB
Task
Force
submitted
a
GC/
ECD
method
for
determining
residues
of
2,4­
DB
and
its
glycine
conjugate
in
beef
tissues
and
milk
(
1997,
MRID
44334704).
The
registrant
has
also
submitted
data
on
the
recovery
of
2,4­
DB
glycine
conjugate
on
account
of
its
significant
contribution
to
the
TRR
as
determined
in
the
ruminant
metabolism
study.
The
HED
Metabolism
Committee
(
D221954,
D.
Miller,
1/
17/
96)
has
concluded
that
2,4­
DB
per
se
is
the
residue
of
concern
in
livestock
commodities.

Residues
in
muscle
are
extracted
with
acidified
acetonitrile
(
ACN),
centrifuged,
filtered,
and
diluted
with
water.
2,4­
DB
Residues
are
sequentially
partitioned
into
diethyl
ether
(
Et
2
O)
then
0.1%
NaOH.
Residues
are
then
concentrated,
acidified
to
pH
2,
and
applied
to
C8
and
C18
columns
eluted
with
methyl
(
tert)
butyl
ether
(
MTBE)
for
cleanup.
The
residues
in
the
eluate
are
concentrated,
and
methylated
using
boron
trifluoride
in
methanol
(
BF
3/
MeOH)
prior
to
analysis
by
GC/
ECD.

Residues
in
fat
are
extracted
with
hexane,
partitioned
into
0.1%
NaOH,
acidified
(
pH
2­
3),
and
partitioned
into
Et
2
O.
Residues
of
2,4­
DB
are
then
purified
and
determined
using
the
same
procedures
described
above
for
muscle.

Residues
in
kidney
and
liver
are
initially
hydrolyzed
in
4N
HCl
(
reflux
2
hours).
Hydrolyzed
residues
are
then
partitioned
into
ACN
and
cleaned
up
on
a
florisil
column
eluted
with
ACN.
Residues
in
the
eluate
are
partitioned
into
1%
NaOH,
acidified
(
pH
2),
concentrated,
and
partitioned
into
ethyl
acetate:
hexane
(
1:
9,
v/
v).
The
organosoluble
residues
are
then
cleaned
up
on
an
alumina
column
eluted
with
MeOH:
1%
NaOH
(
1:
9,
v/
v),
acidified
(
pH
2),
partitioned
into
MTBE,
and
concentrated.
The
2,4­
DB
residues
are
then
methylated
with
BF
3/
MeOH
prior
to
analysis
by
GC/
ECD.

Samples
of
milk
are
hydrolyzed
in
2N
HCl
(
reflux
1
hour),
and
residues
in
the
resulting
hydrolysate
are
extracted
with
ACN.
The
ACN
layer
is
removed
and
the
purification
and
determination
proceed
as
described
above
for
kidney
and
liver.

The
submitted
GC/
ECD
method
used
for
determining
residues
of
2,4­
DB
in
ruminant
tissues
and
milk
are
adequate.
The
validated
limit
of
quantitation
(
LOQ)
of
2,4­
DB
in
tissues
and
milk
is
0.05
ppm
and
0.01
ppm,
respectively.
The
limit
of
detection
(
LOD)
is
0.03
ppm
in
tissue
and
0.006
ppm
in
milk.
Overall
method
recoveries
from
tissue
fortified
at
0.05­
0.2
ppm
and
from
milk
fortified
at
0.01­
0.1
ppm
were
63­
119%
for
2,4­
DB
and
70­
114%
for
2,4­
DB
glycine.

Poultry
The
2,4­
DB
Task
Force
has
submitted
an
analytical
method
for
determining
residues
of
2,4­
DB
in
poultry
tissues
and
eggs
(
1998;
MRID
44546301).
The
HED
Metabolism
Committee
(
D.
Miller,
1/
17/
96)
has
concluded
that
2,4­
DB
per
se
is
the
residue
of
concern
in
livestock
commodities.
The
poultry
metabolism
study
(
DP
Barcodes
D196291,
D197243,
and
D197685,
D.
Miller,
1/
26/
95)
indicated
that
2,4­
DB
parent
compound
was
either
bound
or
conjugated
in
fat
and
egg
yolk
as
32
evidenced
by
the
release
of
2,4­
DB
only
after
base
hydrolysis
following
organic
extraction.
The
registrant
proposed
that
2,4­
DB
is
not
readily
metabolized
by
hens
and
is
incorporated
into
body
fat
and
egg
yolk.
The
submitted
method
includes
a
lipid
saponification
(
base
hydrolysis)
procedure
for
poultry
fat
and
eggs
which
is
intended
to
release
2,4­
DB
fatty
acid
conjugates.

Residues
in
muscle
are
extracted
with
acidified
ACN,
centrifuged,
filtered,
and
diluted
with
deionized
water.
The
extract
is
acidified
(
pH
2)
using
concentrated
HCl,
and
2,4­
DB
residues
are
sequentially
partitioned
into
diethyl
ether
then
0.1%
NaOH.
Residues
are
then
concentrated,
acidified
to
pH
2,
and
applied
to
C8
and
C18
columns
and
eluted
with
MTBE
for
cleanup.
The
residues
in
the
eluate
are
concentrated,
and
methylated
using
boron
trifluoride
in
methanol
(
BF
3/
MeOH)
prior
to
analysis
by
GC/
ECD.

Residues
in
liver
are
extracted
with
acidified
ACN,
centrifuged,
filtered
and
cleaned
up
on
a
Florisil
column
eluted
with
ACN.
Residues
in
the
eluate
are
partitioned
into
1%
NaOH,
acidified
(
pH
2),
concentrated,
and
partitioned
into
ethyl
acetate:
hexane
(
1:
9,
v/
v).
The
organosoluble
residues
are
then
cleaned
up
on
an
alumina
column
eluted
with
MeOH:
1%
NaOH
(
1:
9,
v/
v),
acidified
(
pH
2),
partitioned
into
MTBE,
and
concentrated.
The
2,4­
DB
residues
are
then
methylated
with
BF
3/
MeOH
prior
to
analysis
by
GC/
ECD.

Residues
of
free
2,4­
DB
in
fat
are
extracted
with
hexane,
partitioned
into
1.0%
NaOH,
centrifuged,
and
residues
in
the
NaOH
extract
are
separated
from
the
homogenate
and
retained.
Fatty
acid
conjugates
of
2,4­
DB
in
the
post­
extraction
fat/
hexane
slurry
are
filtered,
concentrated,
and
base
hydrolyzed
by
refluxing
in
a
KOH/
MeOH
solution.
The
hydrolyzed
residues
are
then
concentrated,
reconstituted
in
water,
and
combined
with
the
free
2,4­
DB
residues
in
the
retained
NaOH
solution.
After
acidic
conditions
(
pH
2)
are
established,
the
residues
are
centrifuged,
and
the
resulting
solids
and
supernatant
are
separated.
Residues
in
the
hydrolyzed
solids
are
further
extracted
by
homogenization
with
ACN
and
Celite
®
,
filtered,
and
combined
with
the
residues
retained
in
the
aqueous
supernatant.
The
pH
is
adjusted
to
12
using
1%
NaOH,
and
the
residues
are
concentrated
to
remove
the
ACN,
and
acidified.
The
residues
are
then
partitioned
into
ethyl
acetate:
hexane
(
1:
9,
v/
v),
and
the
organosoluble
residues
purified
and
determined
using
the
same
procedures
described
above
for
liver.

Residues
of
free
2,4­
DB
in
egg
are
extracted
with
hexane,
partitioned
into
1.0%
NaOH,
centrifuged,
and
residues
in
the
aqueous
extract
are
separated
from
the
homogenate
and
retained.
Fatty
acid
conjugates
of
2,4­
DB
in
the
post­
extraction
fat/
hexane
homogenate
are
filtered,
concentrated,
and
base
hydrolyzed
by
refluxing
in
a
KOH/
MeOH
solution.
The
hydrolyzed
residues
are
then
concentrated,
reconstituted
in
water,
and
combined
with
the
free
2,4­
DB
residues
in
the
retained
NaOH
solution.
The
residues
are
acidified
to
pH
2,
partitioned
into
ACN
after
the
addition
of
NaCl,
filtered,
and
residues
in
the
filter
cake
extracted
further
with
ACN
mixed
with
Celite
®
.
Residues
in
the
combined
ACN
extracts
are
cleaned
up
on
a
Florisil
column
eluted
with
ACN,
partitioned
into
1.0%
NaOH,
concentrated
to
remove
ACN,
and
acidified.
Residues
are
then
partitioned
into
ethyl
acetate:
hexane
(
1:
9,
v/
v),
and
the
organosoluble
residues
purified
and
determined
using
the
same
procedures
described
above
for
liver.

The
GC/
ECD
method
used
for
determining
residues
of
2,4­
DB
in
poultry
tissues
and
eggs
is
adequate.
The
validated
LOQ
of
2,4­
DB
in
tissues
and
eggs
are
0.05
ppm
and
0.01
ppm,
33
respectively.
The
limits
of
detection
(
LOD)
are
0.02
ppm
in
tissue
and
0.004
ppm
in
eggs.
Overall
method
recoveries
for
2,4­
DB
from
tissue
fortified
at
0.05­
0.2
ppm
and
from
eggs
fortified
at
0.01­
0.1
ppm
were
58­
122%.

Conclusions:
The
submitted
GC/
ECD
methods
for
ruminant
tissues,
milk,
poultry
tissues
and
eggs
are
adequate
for
data
collection.
A
radiovalidation
study
using
14C­
labeled
samples
has
been
submitted
(
MRID
44997901).
The
radiovalidation
data
show
that
the
analytical
methods
adequately
recover
fortified
residues
of
2,4­
DB
from
whole
egg
and
aged
residues
of
2,4­
DB
from
poultry
fat,
poultry
liver,
and
goat
milk.
If
the
submitted
methods
are
proposed
as
the
enforcement
method(
s)
for
determining
2,4­
DB
in
livestock
commodities,
independent
laboratory
validation
of
the
methods
should
be
performed.

860.1360
Multiresidue
Method
(
MRM)
Testing
2,4­
DB
is
completely
recovered
(>
80%)
by
FDA
MultiResidue
Test
Method
402
(
PAM
Vol
I,
updated
10/
97).

860.1380
Storage
Stability
Data
DER
Reference
List:
44334705,
44997902
,43607001,
43607002.

The
submitted
storage
stability
data
are
adequate
and
indicate
that
2,4­
DB
is
stable
in
frozen
beef
liver
(
91
days),
muscle
(
101
days),
fat
(
105
days),
kidney
(
119
days),
and
milk
(
116
days
;
139
days
for
2,4­
DB
glycine).
These
data
support
the
maximum
storage
intervals
from
the
ruminant
feeding
study
of

35
days
observed
for
tissues
and
milk.

Storage
stability
data
submitted
with
the
poultry
feeding
study
indicate
2,4­
DB
is
relatively
stable
in
frozen
eggs
(
135
days),
fat
(
137
days),
liver
(
127
days,
and
muscle
(
98
days).

The
registrant
did
not
submit
storage
stability
data
for
2,4­
DB
on
alfalfa,
but
indicated
that
alfalfa
forage
and
hay
are
similar
to
soybean
forage
and
hay
which
was
shown
to
be
stable
for
a
period
of
at
least
25
months
(
for
review,
see
D.
Miller,
4/
17/
96,
CBRS
No.
15508,
DP
Barcode
D215038).
The
registrant
also
did
not
provide
any
storage
stability
data
for
peanut
nutmeat,
vines,
hay,
and
hulls
contending
that
these
commodities
are
similar
to
soybean
seed,
forage,
hay,
and
straw,
respectively.
HED
will
translate
storage
stability
data
from
soybean
commodities
to
alfalfa,
peanut,
and
mint
.
The
soybean
storage
stability
data
are
adequate
to
support
the
submitted
field
trial
data.

All
future
plant
and
livestock
magnitude
of
the
residue
studies
must
have
supporting
storage
stability
data.
The
Agency
prefers
that
concurrent
storage
stability
studies
be
conducted.

860.1400
Water,
Fish,
and
Irrigated
Crops
2,4­
DB
is
not
presently
registered
for
direct
use
on
water
and
aquatic
food
and
feed
crops;
therefore,
no
residue
chemistry
data
are
required
under
this
guideline
topic.
34
860.1460
Food
Handling
2,4­
DB
is
not
presently
registered
for
use
in
food
handling
establishments,
therefore,
no
residue
chemistry
data
are
required
under
this
guideline
topic.

860.1480
Meat,
Milk,
Poultry,
Eggs
DER
Reference
List:
44334705,
44997902.

The
ruminant
feeding
study
(
MRID
44334705)
indicates
that
residues
of
2,4­
DB
may
transfer
to
beef
liver
as
a
result
of
the
current
registered
uses
of
2,4­
DB
on
livestock
feedstuffs.
Residues
of
2,4­
DB
were
at
or
below
the
limit
of
quantitation
(

0.01
ppm)
for
all
milk
samples
from
the
1x,
3x,
and
10x
(
the
maximum
theoretical
dietary
burden)
feeding
rate.
For
all
tissue
matrices,
residues
of
2,4­
DB
were
<
0.05
ppm
(
LOQ)
in
samples
from
the
1x
and
3x
dose
groups.
One
sample
each
of
kidney
and
liver
from
the
10x
dose
group
bore
residues
of
2,4­
DB
at
0.05
and
0.11
ppm,
respectively.
All
other
tissue
samples
from
the
10x
dose
group
were
<
0.05
ppm.
The
appropriate
tolerance
for
2,4­
DB
is
0.05
ppm
(
LOQ)
in
the
meat
byproducts
of
cattle,
goats,
hogs,
horses,
and
sheep.
There
is
no
reasonable
expectation
of
the
transfer
of
residues
of
2,4­
DB
from
feedstuffs
to
livestock
meat,
fat
or
milk;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
milk
or
in
the
meat
and
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required.

The
poultry
feeding
study
(
MRID
44997902)
indicates
that
residues
of
2,4­
DB
are
not
expected
to
transfer
to
poultry
eggs
and
tissues
as
a
result
of
the
current
registered
uses
of
2,4­
DB
on
poultry
feedstuffs.
Residues
of
2,4­
DB
were
at
or
below
the
limit
of
quantitation
(
0.01ppm
for
eggs
and
0.05
ppm
for
poultry
tissues)
in
all
samples
at
the
3x
and
10x
(
the
maximum
theoretical
dietary
burden)
feeding
rate;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
poultry
meat,
fat,
meat
byproducts
and
eggs
are
not
required.

TABLE
5.
Calculation
of
Maximum
Theoretical
Dietary
Burden
(
MTDB)
for
Cattle
Feedstuffs
%
Dry
Matter
a
%
Diet
a
Tolerance
(
ppm)
b
Dietary
Contribution
(
ppm)
c
Beef
Cattle
Alfalfa
hay
89
70
2.0
1.57
Soybean
seed
89
15
0.5
0.08
TOTAL
BURDEN
85
1.65
Dairy
Cattle
Alfalfa
hay
89
60
2.0
1.35
Soybean
seed
89
15
0.5
0.08
TOTAL
BURDEN
75
1.43
a
Table
1,
OPPTS
GLN
860.1000.
b
Recommended
tolerances
from
ruminant
study
protocol
review
(
DP
Barcode
D224176,
D.
Miller,
5/
7/
96).
c
Contribution
=
[
tolerance
/
%
DM
(
if
cattle)]
X
%
diet).
35
TABLE
6.
Calculation
of
Maximum
Theoretical
Dietary
Burden
(
MTDB)
for
Poultry
Feedstuffs
%
Diet
a
Tolerance
(
ppm)
b
Dietary
Contribution
(
ppm)
c
Poultry
Soybean
seed
20
0.5
0.1
TOTAL
BURDEN
0.1
a
Table
1,
OPPTS
GLN
860.1000.
b
Recommended
tolerance/
diet
from
ruminant
study
protocol
review
(
DP
Barcode
D224176,
D.
Miller,
5/
7/
96).
c
Contribution
=
[
tolerance
/
%
DM
(
if
cattle)]
X
%
diet).

860.1500
Crop
Field
Trials
DER
Reference
list:
43620301
(
alfalfa),
00116018
(
clover)
,
00102943
(
mint),
43621201
(
peanut),
43607001
(
soybean).

The
following
is
a
summary
of
the
magnitude
of
the
2,4­
DB
residue
studies
for
currently
registered
food/
feed
crops.

Table
7.
Summary
of
Residues
from
the
Crop
Field
Trials
with
2,4­
DB.

Crop
Matrix
Applic.
Rate
(
lb
ae/
A)
PHI
(
days)
Residues
(
ppm)

Min.
Max.
HAFT
Mean
Std.
Dev.

ALFALFA
(
label
use
=
1.3
lb
ae/
A
total
application
rate,
30­
day
PHI
[
60­
day
PHI
seedling)
1
Alfalfa,
forage
(
established)
1.3
28­
34
<
0.05
0.492
0.49
0.23
0.16
Alfalfa,
hay
(
established)
1.3
31­
39
<
0.05
1.73
1.7
0.38
0.44
Alfalfa,
forage
(
seedling)
1.3
59­
62
<
0.05
0.144
0.14
0.05
0.032
Alfalfa,
hay
(
seedling)
1.3
61­
70
<
0.05
0.24
0.24
0.11
0.068
MINT
(
label
use
=
0.64
lb
ae/
A
total
application
rate,
90­
day
PHI)
5
Peppermint,
hay
0.64
133­
212
<
0.01
<
0.01
<
0.01
<
0.005
­

Spearmint,
hay
0.64
133­
212
<
0.01
<
0.01
<
0.01
<
0.005
­

PEANUT
(
label
use
=
0.68
lbae/
A
total
application
rate,
30­
day
PHI)
6
Peanut
(
nutmeat)
0.68
53­
104
<
0.05
<
0.05
<
0.05
0.025
­

Peanut,
hay
0.68
53­
104
0.06
0.55
0.55
0.27
0.16
SOYBEAN
(
label
use
=
0.68
lbae/
A
total
application
rate,
60­
day
PHI)
7
Soybean,
seed
0.68
69­
99
<
0.05
0.45
0.45
0.09
0.12
Soybean,
forage
0.68
13­
35
<
0.05
4.6
4.6
0.81
1.5
Soybean,
hay
0.68
14­
34
<
0.05
6.7
6.7
0.95
2.0
Table
7.
Summary
of
Residues
from
the
Crop
Field
Trials
with
2,4­
DB.

Crop
Matrix
Applic.
Rate
(
lb
ae/
A)
PHI
(
days)
Residues
(
ppm)

Min.
Max.
HAFT
Mean
Std.
Dev.

36
CLOVER
(
label
use
=
1.3
lb
ae/
A
total
application
rate,
PHI
unspecified)
8
Clover
0.84­
1.68
36­
43
<
0.1
<
0.1
<
0.1
<
0.05
­

1
alfalfa:
1.3
lb
ae/
A
based
on
application
of
the
2
lb/
gal
dimethylamine
salt
formulation
(
1.5
lb
ai/
A).
2
2.23
ppm
outlier
excluded
as
per
Dixon
outlier
test
(
D215039
and
D2157586,
D.
miller,
5/
15/
96).
3
8.34
ppm
outlier
excluded
as
per
Dixon
outlier
test
(
D215039
and
D2157586,
D.
miller,
5/
15/
96).
4
1.53
ppm
outlier
excluded
as
per
Dixon
outlier
test
(
D215039
and
D2157586,
D.
miller,
5/
15/
96)
5
mint:
0.64
lb
ae/
A
based
on
application
of
the
2
lb/
gal
EC
isooctyl
ester
formulation
(
1
lb
ai/
A)
6
peanut:
0.68
lb
ae/
A
based
on
application
of
the
2
lb/
gal
dimethylamine
salt
formulation
(
0.8
lb
ai/
A).
7
soybean:
0.68
lb
ae/
A
based
on
application
of
the
2
lb/
gal
dimethylamine
salt
formulation
(
0.8
lb
ai/
A).
8
clover:
0.84­
1.68
lb
ae/
A
based
on
application
of
the
2
lb/
gal
EC
isooctyl
ester
formulation
(
1­
2
lb
ai/
A)

Alfalfa
MRID
43620301
The
2,4­
DB
Task
Force
submitted
data
from
22
trials
conducted
at
13
sites
in
the
states
of
CA(
2),
IA(
2),
MI(
1),
NE(
2),
NY(
1),
PA(
1),
WI(
2),
SD(
1)
and
MN
(
1)
depicting
the
magnitude
of
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
alfalfa
forage
and
hay
(
only
the
results
of
2,4­
DB,
the
residue
of
concern,
will
be
discussed
in
this
memorandum).
At
each
of
the
13
trial
sites,
alfalfa
in
separate
plots
was
treated
using
ground
equipment
at
a
nominal
1.3
lbs
ae/
A
and
harvested
approximately
30,
60,
and
90
days
following
application
(
applied
as
1.5
lb
ai/
A
of
the
2
lb/
gal
dimethylamine
salt
formulation;
1x
the
maximum
label
rate).
Applications
were
made
to
both
spring­
seeded
and
fallseeded
(
established)
alfalfa
and
to
alfalfa
seedlings.
Residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
alfalfa
commodities
were
determined
using
a
GC/
ECD
method.
The
recovery
data
indicate
that
the
GC/
ECD
method
is
adequate
for
2,4­
DB
data
collection
in
alfalfa.

The
residues
of
2,4­
DB
in/
on
alfalfa
forage
at
30
and
60
days
PHI
ranged
from
nondetectable
(<
0.05
ppm)
to
0.49
ppm
(
excluding
a
2.23
ppm
outlier)
and
nondetectable
to
0.14
ppm
(
excluding
a
1.53
ppm
outlier)
in/
on
established
or
newly­
seeded
alfalfa,
respectively,
following
treatment
with
1.3
lbs
ae/
A
per
label
directions.

The
residues
of
2,4­
DB
in/
on
alfalfa
hay
treated
at
approximately
30
days
PHI
ranged
from
nondetectable
(<
0.05
ppm)
to
1.7
ppm.

Apparent
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
in/
on
nine
samples
of
22
untreated
alfalfa
forage.
Detected
levels
on
the
remaining
forage
control
samples
ranged
from
0.05
ppm
to
0.32
ppm.
With
26
control
hay
samples,
residues
were
ND
(<
0.05
ppm)
on
15
samples,
with
detectable
residues
of
from
0.12
to
0.40
ppm
on
the
remaining
untreated
samples.
The
registrant
contends
that
many
of
these
apparent
residues
were
observed
primarily
as
broad,
non­
analyte
chromatographic
peaks
with
retention
times
similar
to
that
of
the
analyte.
While
HED
believes
that
the
registrant
did
not
adequately
demonstrate
this
explanation,
HED
will
conclude
that
these
control
analyses
are
acceptable
and
do
not
adversely
affect
interpretation
of
the
data.
37
Geographic
representation
is
adequate
since
the
test
states
of
CA,
IA,
MI,
NE,
NY,
PA,
WI,
SD
and
MN
represent
the
majority
of
alfalfa
growing
regions.

Alfalfa
samples
were
stored
frozen
(
from
­
33
to
­
7

F)
for
less
than
two
years
between
sample
collection
and
sample
extraction.
While
no
storage
stability
data
were
obtained
for
2,4­
DB
in
alfalfa
commodities,
alfalfa
forage
and
hay
are
similar
to
soybean
forage
and
hay,
in
which
residues
of
2,4­
DB
were
shown
to
be
stable
for
a
period
of
at
least
25
months.
The
soybean
storage
stability
data
support
the
storage
intervals
in
the
alfalfa
field
trials.

Based
on
the
submitted
alfalfa
field
trials,
the
current
tolerance
for
alfalfa
forage
of
0.2(
N)
ppm
should
be
increased
to
0.7
ppm.
There
is
no
current
tolerance
for
alfalfa
hay.
Based
on
a
30
day
precutting
interval,
the
registrant
should
propose
a
tolerance
on
alfalfa
hay
of
2.0
ppm.
The
submitted
field
trial
data
on
alfalfa
may
be
translated
to
trefoil.

Clover
MRID
00116018
Data
were
submitted
from
four
clover
(
crimson
and
ladino)
field
trials
conducted
in
CA
(
2)
and
OR(
2).
Residues
of
2,4­
DB
were
nondetectable
(<
0.10
ppm)
in
4
clover
samples
harvested
36­
43
days
following
one
postemergent
broadcast
application
of
0.84­
1.68
lb
ae/
A
2,4­
DB
(
0.65x­
1.3
x
the
proposed
maximum
label
rate
of
1.3
lb
ae/
A,
applied
as
the
2
lb/
gal
EC
isooctyl
ester
formulation).
Samples
were
analyzed
using
a
GLC
method
with
electron
capture
detection.
Samples
were
stored
frozen
at
an
unspecified
temperature
for
85
days.
(
2,4­
DB
Registration
Standard,
C.
Trichilo,
2/
1/
88).

Additional
field
trials
on
clover
forage
and
hay
are
required
at
the
maximum
label
rate
with
a
60
day
PHI
to
reassess
the
2,4­
DB
tolerance.
Ten
additional
trials
are
recommended
in
the
following
regions:
1
(
Region1),
1
(
Region
2),
1
(
Region
4),
3
(
Region
5),
1
(
Region
6),
1
(
Region7),
1
(
Region
8),
1
(
Region
9).
Alternatively,
if
a
crop
group
tolerance
for
NonGrass
Animal
Feeds
(
CG18)
is
desired,
eight
additional
trials
are
recommended
in
the
following
regions:
1
(
Region1),
1
(
Region
2),
1(
Region
4),
2
(
Region
5),
1
(
Region
6),
1
(
Region
7),
1
(
Region
8).

Mint
MRID
00102943
IR­
4
submitted
field
trial
data
from
6
trials
conducted
in
OR
(
4)
and
WA
(
2)
depicting
the
magnitude
of
residue
of
2,4­
DB
(
and
2,4­
D)
on
peppermint
and
spearmint
hay.
Residues
of
2,4­
DB
were
nondetectable
(<
0.01
ppm)
in
12
peppermint
hay
samples
and
in
6
spearmint
hay
samples
harvested
133­
212
days
following
one
postemergent
application
of
1
lb
ae/
A
2,4­
DB
(
1.6
x
the
proposed
maximum
label
rate
of
0.64
lb
ae/
A,
applied
as
the
2
lb/
gal
EC
isooctyl
ester
formulation).
Samples
were
analyzed
using
a
GLC/
microcoulimetric
method
which
is
adequate
for
data
collection.
Sample
storage
information
was
not
provided
(
PP#
6E1736,
R.
J.
Hummel,
6/
2/
1976).

A
subsequent
review
of
a
Special
Local
Need
request
concluded
that
2,4­
DB
residues
would
not
exceed
the
established
tolerance
of
0.2
ppm
in
mint
hay
if
a
preharvest
interval
of
90
days
is
observed
following
early
postemergence
application
of
the
dimethylamine
salt
to
mint
at
rates
up
to
38
0.75
lb
ai/
A
(
0.64
lb
ae/
A)(
D217848,
J.
Garbus,
8/
22/
95).

Peanut
MRID
43621201
The
2,4­
DB
Task
Force
submitted
data
from
11
trials
conducted
at
11
sites
in
the
states
of
AL(
2),
FL,
GA(
3),
NC,
TX(
3),
and
VA
depicting
the
magnitude
of
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
peanut
vines,
nutmeat,
hulls,
and
hay
(
only
the
results
of
2,4­
DB,
the
residue
of
concern,
will
be
discussed
in
this
memorandum.
Since
peanut
vines
and
hulls
are
no
longer
considered
significant
livestock
feedstuff,
those
results
are
not
presented
here).
At
each
of
the
11
trial
sites,
2,4­
DB
was
applied
to
peanuts
(
broadcast)
at
2
applications
of
0.34
lbs
ae/
A
(
total
application
of
0.68
lb
ae/
A
applied
as
0.8
lb
ai/
A
of
the
2
lb/
gal
dimethylamine
salt
formulation;
1x
the
maximum
label
rate;
retreatment
interval
about
28
days).
Residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
peanut
commodities
were
determined
using
a
GC/
ECD
method.
The
recovery
data
indicate
that
the
GC/
ECD
method
is
adequate
for
2,4­
DB
data
collection
in
peanuts.

Residues
of
2,4­
DB
in/
on
all
11
samples
of
peanut
nutmeat
harvested
53
days
following
a
total
application
of
2,4­
DB
at
0.8
lbs
ae/
A
were
nondetectable
(<
0.05
ppm).
Residues
in
peanut
hay
from
the
11
trial
sites
ranged
from
0.08
ppm
to
0.55
ppm
Apparent
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
in/
on
two
of
2
samples
of
untreated
peanut
nutmeat.
Four
samples
of
peanut
hay
displayed
residues
of
0.09,
0.26,
0.21,
and
0.06
ppm.

Geographic
representation
is
adequate
since
the
test
states
of
AL,
FL,
GA,
NC,
TX,
and
VA
represent
the
majority
of
peanut
growing
regions.

Peanut
samples
were
stored
frozen
(
from
­
32
to
0

F)
for
less
than
two
years
between
sample
collection
and
sample
extraction.
While
no
storage
stability
data
were
obtained
for
2,4­
DB
in
peanut
commodities,
peanut
nutmeat
and
hay
are
similar
to
soybean
seed
and
hay,
in
which
residues
of
2,4­
DB
were
shown
to
be
stable
for
a
period
of
at
least
25
months.
The
soybean
storage
stability
data
support
the
storage
intervals
in
the
peanut
field
trials.

The
application
schedules
in
the
peanut
field
trials
represent
PHIs
of
53
to
104
days.
Current
labels
specify
a
minimun
30
day
PHI.
The
current
tolerance
(
based
on
combined
residues
of
2,4­
DB
and
2,4­
D
for
peanut
nutmeat
of
0.2(
N)
ppm)
can
be
lowered
to
0.05
ppm.
The
labels
should
be
modified
to
specify
a
minimum
60
day
PHI.

Soybean
MRID
43607001
The
2,4­
DB
Task
Force
submitted
data
from
56
trials
conducted
at
13
trial
sites
in
AR(
2),
GA(
2),
IL(
2),
IN(
1),
IA(
2),
LA(
2),
MN(
1),
and
NC(
1)
depicting
the
magnitude
of
residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
soybean
forage,
hay,
seed,
and
straw
(
only
the
results
of
2,4­
DB,
the
residue
of
concern,
will
be
discussed
in
this
memorandum.
Since
soybean
straw
is
not
considered
a
significant
livestock
feedstuff,
those
results
are
not
presented
here).
Five
different
application
scenarios
were
tested,
with
the
most
severe
being
two
postemergence
directed
applications,
one
at
a
39
crop
height
of
8­
12
inches
and
the
other
at
early
to
mid
bloom
(
total
application
of
approximately
0.68
lb
ae/
A
applied
as
0.8
lb
ai/
A
of
the
2
lb/
gal
dimethylamine
salt
formulation;
1x
the
maximum
label
rate;
data
from
other
[
lower]
application
rates
are
not
presented
here).
Residues
of
2,4­
DB,
2,4­
D,
and
2,4­
DCP
in/
on
soybean
commodities
were
determined
using
a
GC/
ECD
method.
The
recovery
data
indicate
that
the
GC/
ECD
method
is
adequate
for
2,4­
DB
data
collection
in
soybeans.
The
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
to
0.45
ppm
in/
on
soybeans
harvested
69­
99
days
following
the
last
of
two
postemergence
directed
applications
at
the
maximum
label
rate.

The
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
to
4.6
ppm
in/
on
soybean
forage
harvested
13­
35
days
following
the
last
of
two
postemergence
directed
applications
at
the
maximum
label
rate.

The
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
to
6.7
ppm
in/
on
soybean
hay
harvested
14­
40
days
following
the
last
of
two
postemergence
directed
applications
at
the
maximum
label
rate.

Apparent
residues
of
2,4­
DB
were
nondetectable
(<
0.05
ppm)
in/
on
seven
samples
of
untreated
forage,
seven
samples
of
untreated
hay,
six
samples
of
untreated
seed,
and
four
samples
of
untreated
straw.
Detectable
residues
of
2,4­
DB
were
observed
in
duplicate
analyses
of
one
sample
of
untreated
hay
at
0.071
and
0.083
ppm.
In
addition,
two
samples
each
of
untreated
forage,
hay,
and
straw,
and
one
sample
of
untreated
seed
were
analyzed
in
replicate.
For
each
sample,
detectable
residues
of
2,4­
DB
were
observed
in
some
but
not
all
replicates
at
the
following
levels:
0.10­
0.60
ppm
in/
on
forage;
0.056­
0.16
ppm
in/
on
hay;
0.056
and
0.23
ppm
in/
on
seed;
and
0.064­
0.11
ppm
in/
on
straw.

Geographic
representation
is
adequate
since
the
test
states
of
AR(
5%),
GA(
1%),
IL(
17%),
IN(
9%),
IA(
18%),
LA(
1%),
MN(
10%),
and
NC(
2%)
accounted
for

63%
of
the
1991
U.
S.
production
of
soybeans
The
submitted
storage
stability
data
indicate
that
fortified
residues
of
2,4­
DB
are
stable
in/
on
soybean
forage,
hay,
seed,
and
straw
for
at
least
25
months,
and
are
adequate
to
support
the
submitted
field
trial
data.

The
submitted
soybean
field
trial
data
are
adequate
to
satisfy
reregistration
requirements
for
magnitude
of
the
residue
of
2,
4
DB
in
soybean
seed;
the
established
tolerance
of
0.2
ppm
should
be
increased
to
0.5
ppm.

The
submitted
soybean
field
trial
data
are
also
adequate
(
although
minimally)
to
satisfy
reregistration
requirements
for
magnitude
of
the
residue
in
soybean
forage.
2,4­
DB
residues
in
soybean
forage
following
treatments
at
maximal
label
rates
are
unlikely
to
exceed
0.7
ppm
(
with
a
60­
day
pregrazing
interval
[
PGI])
and
HED
will
thus
recommend
for
a
tolerance
of
0.7
ppm.

Since
only
minimal
data
were
provided
for
soybean
hay
at
a
60­
day
PHI,
HED
recommends
that
the
registrant
propose
a
tolerance
based
on
a
forage­
to­
hay
dry­
down
factor.
Based
on
the
HEDrecommended
0.7
ppm
tolerance
for
forage,
%
DM
values
of
35%
and
85%
for
forage
and
hay,
respectively,
and
a
consequent
dry­
down
factor
of
2.4x,
a
tolerance
of
2
ppm
would
be
appropriate
for
soybean
hay.
40
Note
that
the
current
PHI
restrictions
against
the
feeding
of
2,4­
DB­
treated
soybean
forage
and
hay
are
ambiguous
and
the
registrant
should
be
required
to
clarify
these
instructions.
For
example,
the
labels
for
EPA
Reg.
No.
56077­
26
(
now
66222­
76)
and
EPA
Reg
No.
56077­
52
(
now
66222­
80)
only
prohibit
the
grazing
of
forage
or
feeding
of
hay
within
60
days
of
the
application
of
a
tank
mix
with
Lorax
50W
application,
and
there
is
no
indication
of
any
restriction
when
2,4­
DB
is
applied
alone.
The
restriction
should
be
against
feeding/
grazing
soybean
forage
and
harvesting
hay
for
60
days
following
any
2,4­
DB
application.

[
HED
will
not
require
that
the
registrant
submit
data
pertaining
to
soybean
aspirated
grain
fractions.
This
data
was
originally
required
by
the
2,4­
DB
Reregistration
Standard.
Since
all
later­
season
uses
are
directed
band
applications
and
residues
in
seed
would
likely
result
only
from
systemic
uptake,
it
is
unlikely
that
surface
residues
on
soybean
seeds
would
be
significant.]

860.1520
Processed
Food
and
Feed
DER
Reference
List:
00102943,
00161196
(
mint),
43621201
(
peanut),
43607002
(
soybean).

The
magnitude
of
the
residue
data
for
processed
commodities
of
food/
feed
crops
that
are
presently
registered
use
sites
have
been
evaluated
and
deemed
adequate.
Residues
of
2,4­
DB
do
not
significantly
concentrate
upon
processing.

Residues
of
2,4­
DB
did
not
concentrate
in
meal,
or
crude
and
refined
oil
processed
from
peanut
nutmeat
bearing
detectable
residues
of
2,4­
DB
following
treatment
with
exaggerated
rates
of
2,4­
DB
(
up
to1.8x
the
maximum
label
rate
of
0.68
lb
ae/
A).
Tolerances
are
not
needed
for
2,4­
DB
in
peanut
processed
commodities.
(
A
processing
factor
of
0.72x
may
be
used
for
peanut
oil
in
the
dietary
assessment.)

Residues
of
2,4­
DB
did
not
appear
to
concentrate
in
mint
oil.
Residues
of
2,4­
DB
were
nondetectable
(<
1.5
ppm)
in
samples
of
peppermint
hay
and
peppermint
oil
following
application
of
2,4­
DB
at
1.6x
(
1
lb
ae/
A)
the
maximum
label
rate
(
0.64
lb
ae/
A).
In
another
study,
following
application
between
0.78x
and
1.6x,
residues
of
2,4­
DB
were
<
0.01
ppm
(
LOQ)
in
peppermint
and
spearmint
hay
and
<
0.02
ppm
(
LOQ)
in
mint
oil.
(
A
processing
factor
of
1x
is
appropriate
for
mint
oil
in
the
dietary
assessment.)

Residues
of
2,4­
DB
did
not
concentrate
in
hulls,
meal,
and
crude
and
refined
oil
processed
from
soybeans
bearing
nondetectable
residues
of
2,4­
DB
following
treatment
with
a
single
postemergence
broadcast
application
at
early­
to
midbloom
of
the
2
lb
ae/
gal
SC/
L
formulation
at
0.66
lb
ae/
A
or
a
single
postemergence
directed
application
of
the
same
formulation
at
early­
to
midbloom
at
1.2
lb
ae/
A
(
1.8x).
(
A
processing
factor
of
1x
is
appropriate
for
soybean
oil
in
the
dietary
assessment.)

Normally,
quantifiable
levels
of
regulated
compounds
must
be
present
in
the
RAC
prior
to
processing
so
that
concentration
factors
can
be
calculated.
Although
detectable
residues
of
parent
2,4­
DB
were
not
observed
in
the
treated
soybean
RAC,
since
the
application
rate
is
considered
to
be
close
to
the
maximum
practical
application
due
to
potential
phytotoxicity
concerns,
HED
will
accept
the
current
soybean
processing
study
as
adequate
and
conclude
that
no
separate
tolerances
are
required
for
processed
commodities
of
soybean.
41
860.1650
Submittal
of
Analytical
Reference
Standards
Analytical
reference
standards
must
be
supplied
as
requested
by
the
EPA
National
Pesticide
Standards
Repository
for
2,4­
DB.
Standards
may
be
sent
to
:

USEPA
National
Pesticide
Standards
Repository/
Analytical
Chemistry
Branch/
OPP
710
Mapes
Road
Fort
George
G.
Meade,
MD
20755­
5350
860.1850
Confined
Accumulation
in
Rotational
Crops
and
860.1900
Field
Accumulation
in
Rotational
Crops
DER
Reference
List:
43004301.

The
2,4­
DB
Task
Force
submitted
the
results
of
a
confined
rotational
crop
study
with
2,4­
DB.
Uniformly
ring
labeled
[
14C]
2,4­
DB
was
sprayed
directly
onto
the
soil
surface
of
sandy
loam
soil
at
a
target
rate
of
1.5
lb
ai/
A;
the
actual
application
rate
was
verified
at
1.65
lb
ai/
A.
Rotational
crops
consisting
of
barley
(
a
small
grain
crop),
carrot
(
a
root
crop),
and
lettuce
(
a
leafy
vegetable
crop)
were
planted
30,
120,
and
365
days
after
treatment
(
DAT).
At
appropriate
crop
growth
stages,
immature
and
mature
samples
of
the
rotated
crops
were
collected
from
each
plantback
interval
(
PBI).

The
total
radioactive
residues
(
TRR;
expressed
as
2,4­
DB
equivalents)
in/
on
treated
rotational
crop
commodities
were,
overall,
low
and
ranged
from
<
0.01
ppm
(
365­
DAT
carrot
root)
to
0.07
ppm
(
120­
DAT
barley
straw).
There
appears
to
be
no
discernible
trend
as
to
whether
residues
would
increase
or
decrease
at
longer
PBI
because
of
low
TRR.

Radioactive
residues
in/
on
rotational
crop
commodities
were
sequentially
extracted
with
a
polar
solvent
(
methanol:
water)
and
a
non­
polar
solvent
(
ethyl
acetate)
followed
by
hydrolysis
with
hydrochloric
acid
and
sodium
hydroxide.
Extracts
and
hydrolysates
which
contained
radioactivity
level
of
>
0.01
ppm
were
analyzed
by
adequate
chromatographic
techniques
(
HPLC
and
TLC).

The
parent
compound,
2,4­
DB,
was
not
detected
in
any
plant
matrix
at
any
rotational
interval.
The
metabolites
identified
in
rotational
crop
samples
include
the
phenols
(
2­
chloro­
4­
hydroxyphenol;
2,4­
dichlorophenol;
2,5­
dichloro­
4­
hydroxyphenol;
2,4­
dichloro­
3­
hydroxyphenol;
and
2,3­
dichloro­
4­
hydroxyphenol),
the
phenoxyacetic
acids
(
2,3­
dichloro­
4­
hydroxyphenoxyacetic
acid;
2,5­
dichloro­
4­
hydroxyphenoxyacetic
acid;
and
2,4­
dichloro­
3­
hydroxyphenoxyacetic
acid)
and
1,4­
benzoquinone.
Each
metabolite
identified
comprised
<
3%
of
TRR
except
for
2,4­
dichlorophenol
which
was
detected
at
10.91%
of
TRR
in
120­
DAT
barley
forage.
No
single
metabolite
was
observed
at
a
residue
level
exceeding
0.01
ppm.

The
remaining
nonextractable
residues
of
365­
DAT
barley
forage
were
subjected
to
cell
wall
fractionation
in
order
to
determine
the
nature
of
bound
residues.
The
nonextractable
residues
were
characterized
to
be
associated
with
cellulose
(

26%
TRR)
and
hemicellulose
(

7%
TRR),
with
minor
amounts
of
starch
and
pectin
(
each
<
1%
TRR),
protein
(

2%
TRR),
and
lignin
(<
2%
TRR).
42
The
confined
rotational
crop
studies
showed
that
no
significant
residues
of
2,4­
DB
are
taken
up
in
succeeding
rotational
crops.
The
registrant
proposes
that
the
major
metabolic
pathways
in
rotational
crop
matrices
encompass
side
chain
degradation,
chlorine
shift
and
ring
hydroxylation
as
demonstrated
by
the
observed
metabolites.
 ­
oxidation
of
the
side
chain
(
yielding
2,4
D)
did
not
appear
to
be
a
metabolic
pathway
in
rotational
crops.

TOLERANCE
REASSESSMENT
SUMMARY
Tolerances
listed
under
40
CFR
§
180.331:

Tolerances
for
residues
of
2,4­
DB
in
plant
commodities
are
currently
expressed
as
the
combined
residues
of
the
herbicide
4­(
2,4­
dichlorophenoxy)
butyric
acid
and
its
metabolite
2,4­
dichlorophenoxyacetic
acid.
Current
tolerance
levels
are
set
at
0.2
ppm
based
on
negligible
residues
in
all
crops
.
Neither
tolerances
in
livestock
commodities
nor
food/
feed
tolerances
for
processed
commodities
have
been
established.
The
HED
Metabolism
Committee
concluded
that
the
residue
to
be
regulated
in
plant
and
livestock
commodities
is
2,4­
DB
per
se.

Based
on
the
HED
Metabolism
Committee
decision
and
available
residue
field
trial
data
for
2,4­
DB,
and
in
maintaining
consistency
with
the
2,4­
D
recommended
tolerances
(
D287660,
W.
Hazel,
undergoing
completion),
the
tolerance
for
residues
of
2,4­
DB
in
plant
commodities
should
be
expressed
as
residues
of
2,4­
DB,
both
free
and
conjugated,
determined
as
the
acid.
The
reassessed
tolerances
for
plants
are
listed
as
follows:
alfalfa
forage
(
0.70
ppm),
alfalfa
hay
(
2.0
ppm),
clover
forage
and
clover
hay
(
insufficient
data),
mint
(
0.20
ppm),
soybean
seed
(
0.50
ppm),
soybean
forage
(
0.70
ppm),
soybean
hay
(
2.0
ppm),
peanut
(
0.05
ppm),
trefoil
forage
(
0.7
ppm)
and
trefoil
hay
(
2.0
ppm).
See
Table
8
for
modifications
in
commodity
definitions.

Based
on
the
HED
Metabolism
Committee
decision
and
the
livestock
feeding
studies,
and
in
maintaining
consistency
with
the
2,4­
D
recommended
tolerances
(
D287660,
W.
Hazel,
undergoing
completion),
the
tolerance
for
residues
of
2,4­
DB
in
livestock
commodities
should
be
expressed
as
residues
of
2,4­
DB,
both
free
and
conjugated,
determined
as
the
acid.
The
appropriate
tolerance
for
2,4­
DB
is
0.05
ppm
(
LOQ)
in
the
meat
byproducts
of
cattle,
goats,
hogs,
horses,
and
sheep.
There
is
no
reasonable
expectation
of
the
transfer
of
residues
of
2,4­
DB
from
feed
items
to
livestock
meat,
fat
or
milk;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
milk
and
in
meat
and
fat
of
cattle,
goats,
hogs,
horses,
and
sheep
are
not
required.

The
poultry
feeding
study
(
MRID
44997902)
indicates
that
residues
of
2,4­
DB
are
not
expected
to
transfer
to
poultry
eggs
and
tissues
as
a
result
of
the
current
registered
uses
of
2,4­
DB
on
poultry
feedstuffs;
therefore,
the
current
use
of
2,4­
DB
with
respect
to
these
commodities
should
be
classified
as
Category
3
under
40
CFR
180.6(
a),
and
tolerances
for
residues
of
2,4­
DB
in
poultry
meat,
fat,
meat
byproducts
and
eggs
are
not
required.
43
Sufficient
data
are
available
to
determine
that
residues
of
2,4­
DB
do
not
significantly
concentrate
in
any
peanut,
soybean
or
mint
processed
food/
feed
item;
thus,
tolerances
are
not
required
in
the
processed
commodities
of
these
crops.

Table
8.
Tolerance
Reassessment
Summary
for
2,4­
DB
Commodity
Current
Tolerance
(
ppm)
Tolerance
Reassessment
Comment/
Correct
Commodity
Definition
Tolerances
listed
under
40
CFR
§
180.331
Alfalfa
0.2
(
N)
Revoke
Separate
tolerances
should
be
establishes
for
alfalfa,
forage
and
alfalfa,
hay
at
0.7
ppm
and
2.0ppm,
respectively.
Negligible
residue
designation
(
N)
is
inappropriate.

Clover
0.2
(
N)
Revoke
Separate
tolerances
should
be
establishes
for
clover,
forage
and
clover,
hay.
Additional
data
are
needed
to
reassess
tolerance.
Negligible
residue
designation
(
N)
is
inappropriate.

Mint,
hay
0.2
Revoke
Separate
tolerances
should
be
establishes
for
peppermint,
tops
and
spearmint,
tops
each
at
0.2
ppm
Peanut
0.2
(
N)
0.05
Trefoil,
birdsfoot
0.2
(
N)
Revoke
Separate
tolerances
should
be
establishes
for
trefoil,
forage
and
trefoil,
hay
at
0.7
ppm
and
2.0
ppm,
respectively.
Negligible
residue
designation
(
N)
is
inappropriate.

Soybean
0.2
(
N)
0.50
Negligible
residue
designation
(
N)
is
inappropriate.
[
soybean,
seed]
44
Soybean,
hay
0.2
(
N)
2.0
Negligible
residue
designation
(
N)
is
inappropriate.

Tolerances
needed
under
40
CFR
§
180.331
Alfalfa,
forage
­­­
0.70
Alfalfa,
hay
­­­
2.0
Clover,
forage
­­­
tbd
Additional
data
are
needed
before
tolerance
can
be
recommended.

Clover,
hay
­­­
tbd
Additional
data
are
needed
before
tolerance
can
be
recommended.

Peppermint,
tops
­­­
0.20
Spearmint,
tops
­­­
0.20
Soybean,
forage
­­­
0.70
Trefoil,
forage
­­­
0.70
Trefoil,
hay
­­­
2.0
Cattle,
meat
byproducts
­­­
0.05
Goat,
meat
byproducts
­­­
0.05
Hog,
meat
byproducts
­­­
0.05
Horse,
meat
byproducts
­­­
0.05
Sheep,
meat
byproducts
­­­
0.05
Codex
Harmonization
There
are
no
proposed
or
established
Codex
MRLs
for
residues
of
2,4­
DB
in/
on
food/
feed
items;
therefore,
there
are
no
compatibility
questions
with
respect
to
U.
S.
tolerances
and
Codex
MRLs.
45
O
Cl
Cl
O
OH
O
Cl
Cl
O
O
CH
3
Cl
Cl
O
O
CH
3
O
APPENDIX
1
2,4­
DB
and
its
Metabolites
in
Plants
and
Livestock
Tissues.

Common
Name
Chemical
Name
Structure
Substrate
2,4­
DB
(
4­(
2,4­
dichlorophenoxy)­
butyric
acid
alfalfa
forage
and
hay
peanut
forage,
hay,
and
vines
soybean
forage,
hay,
seed,
pods,
and
vines
hen
liver,
fat,
and
egg
yolk
goat
liver
and
kidney
2,4­
DB
methyl
ester
(
4­(
2,4­
dichlorophenoxy)
butyric
acid,
methyl
ester
alfalfa
forage
peanut
forage
and
hay
2,4­
DB
butyl
ester
(
4­(
2,4­
dichlorophenoxy)
butyric
acid,
butyl
ester
peanut
forage
and
hay
soybean
hay,
seed,
and
pods
Common
Name
Chemical
Name
Structure
Substrate
46
Cl
Cl
O
O
CH
3
O
O
O
Cl
Cl
HO
OH
Cl
Cl
HO
O
OH
O
O
O
H
Cl
O
OH
Cl
Cl
Cl
OCH
3
2,4­
DB
ethyl
ester
(
4­(
2,4­
dichlorophenoxy)
butyric
acid,
ethyl
ester
peanut
vines
1,4­
BQ
1,4­
benzoquinone
soybean
forage,
hay,
seed,
pods,
and
vines
2,3­
Cl­
4­
HOH
2,3­
dichloro­
4­
hydroxyphenol
peanut
forage,
hay,
and
vines
soybean
hay
and
vines
2,3­
Cl­
4­
HPAA
2,3­
dichloro­
4­
hydroxyphenoxyacetic
acid
peanut
forage,
seed,
hulls,
and
vines
soybean
forage
and
vines
2,3­
Cl­
4­
HPBA
2,3­
dichloro­
4­
hydroxyphenoxybutyric
acid
peanut
forage
soybean
hay
and
vines
2,3­
DCA
2,3­
dichloroanisole
soybean
forage,
hay
and
vines
Common
Name
Chemical
Name
Structure
Substrate
47
Cl
OH
Cl
O
OH
O
O
Cl
Cl
HO
OH
O
Cl
O
O
OH
OH
Cl
O
Cl
Cl
HO
OH
O
OH
Cl
OH
Cl
2,4­
Cl­
3­
HPAA
2,4­
dichloro­
3­
hydroxyphenoxyacetic
acid
peanut
forage,
hay,
and
vines
soybean
forage,
hay,
and
vines
2,4­
Cl­
5­
HPAA
2,4­
dichloro­
5­
hydroxyphenoxyacetic
acid
peanut
forage
and
vines
soybean
hay
and
vines
2,4­
Cl­
6­
HPBA
2,4­
dichloro­
6­
hydroxyphenoxybutyric
acid
alfalfa
hay
peanut
vines
soybean
vines
2,4­
Cl­
5­
HPBA
2,4­
dichloro­
5­
hydroxyphenoxybutyric
acid
peanut
hay
and
vines
soybean
forage
and
vines
2,4­
Cl­
6­
HOH
2,4­
dichloro­
6­
hydroxyphenol
peanut
vines
soybean
hay
and
vines
Common
Name
Chemical
Name
Structure
Substrate
48
O
OH
O
Cl
Cl
OH
Cl
Cl
O
O
CH
3
O
Cl
Cl
O
O
O
CH
3
O
Cl
Cl
OH
O
Cl
OH
Cl
2,4­
Cl­
6­
HPAA
2,4­
dichloro­
6­
hydroxyphenoxyacetic
acid
alfalfa
hay
peanut
forage,
hay,
seed,
and
vines
soybean
forage,
hay,
pods,
and
vines
2,4­
D
methyl
ester
2,4­
dichlorophenoxyacetic
acid,
methyl
ester
soybean
vines
2,4­
D
ethyl
ester
2,4­
dichlorophenoxyacetic
acid,
ethyl
ester
soybean
hay
and
vines
2,4­
D
2,4­
dichlorophenoxyacetic
acid
alfalfa
forage
and
hay
peanut
forage
and
hay
soybean
forage,
hay,
and
vines
hen
liver
goat
liver
and
kidney
2,4­
D
phenol
2,4­
dichlorophenol
alfalfa
forage
and
hay
peanut
hay
soybean
forage
and
hay
hen
liver
goat
liver
and
kidney
Common
Name
Chemical
Name
Structure
Substrate
49
O
OH
O
O
H
Cl
Cl
O
O
OH
O
H
Cl
Cl
O
O
OH
Cl
Cl
OH
Cl
OH
O
Cl
O
CH
3
O
2,5­
Cl­
4­
HPAA
2,5­
dichloro­
4­
hydroxyphenoxyacetic
acid
alfalfa
hay
soybean
forage,
pods,
and
vines
2,5­
Cl­
4­
HPBA
2,5­
dichloro­
4­
hydroxyphenoxybutyric
acid
alfalfa
forage
and
hay
peanut
forage
and
hay
3,5­
Cl­
2­
HPBA
3,5­
dichloro­
2­
hydroxyphenoxybutyric
acid
alfalfa
forage
soybean
forage
4­
CP
4­
chlorophenol
alfalfa
hay
soybean
hay
4­
CPA
methyl
ester
4­
chlorophenoxyacetic
acid,
methyl
ester
soybean
forage
and
hay
Common
Name
Chemical
Name
Structure
Substrate
50
Cl
O
OH
O
O
Cl
O
O
CH
3
OH
OH
Cl
Cl
OH
Cl
HO
O
Cl
Cl
N
H
OH
O
O
4­
CPA
4­
chlorophenoxyacetic
acid
alfalfa
forage
and
hay
peanut
forage,
hay,
seed,
and
vines
soybean
forage,
hay
and
vines
4­
CPA
butyl
ester
4­
chlorophenoxyacetic
acid,
butyl
ester
peanut
hay
and
vines
soybean
forage,
hay,
and
vines
4,6­
DCR
4,6­
dichlororesorcinol
alfalfa
forage
peanut
hay
soybean
forage,
hay,
and
vines
CHQ
chlorohydroquinone
peanut
hay,
seed,
hulls,
and
vines
soybean
forage,
hay
and
vines
2,4­
DB
glycine
4­(
2,4­
dichlorophenoxy)­
butyryl
glycine
goat
milk,
liver,
and
kidney