UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
Subject:
4­
Chlorophenoxyacetic
Acid
(
4­
CPA)
TRED:
Estimated
Drinking
Water
Concentrations
for
4­
CPA
for
Use
in
the
Human
Health
Drinking
Water
Risk
Assessment.
(
Chemical
Code
019401
;
DP
Barcode
D284988)

To:
Christina
Scheltema,
Chemical
Review
Manager
Reregistration
Branch
III
Special
Review
and
Reregistration
Division
(
7505C)

From:
Mark
Corbin,
Environmental
Scientist
Environmental
Risk
Branch
I
Environmental
Fate
and
Effects
Division
(
7507C)

Thru:
Sid
Abel,
Branch
Chief
Environmental
Risk
Branch
I
Environmental
Fate
and
Effects
Division
(
7507C)

This
memorandum
transmits
the
FQPA
drinking
water
assessment
for
the
tolerance
reassessment
of
4­
CPA.
The
use
of
4­
CPA
is
limited
to
indoor
use
as
a
root
suppression
agent
for
mung
bean
sprouts
and
therefore
the
agency
only
required
the
submission
of
hydrolysis
data
in
support
of
the
registration
of
4­
CPA.
No
drinking
water
assessment
has
been
completed
at
this
time
for
4­
CPA
since
an
indoor
use
is
expected
to
minimally
impact
drinking
water
sources.

Environmental
Fate
Assessment
Hydrolysis
data
were
the
only
data
required
to
support
the
indoor
use
(
e.
g.
root
suppression
of
mung
bean
sprouts)
of
4­
CPA.
From
an
acceptable
study,
parent
4­
CPA
was
stable
with
a
reported
half
life
of
greater
than
30
days
to
abiotic
hydrolysis
in
three
buffer
solutions
(
MRID
42819601).
No
additional
environmental
fate
data
are
required
to
support
the
use
of
4­
CPA
on
mung
beans.

4­
CPA
is
expected
to
be
mobile
in
soil
and
aquatic
environments
because
it
will
exist
as
an
anion
(
dissociated
carboxylic
acid)
in
most
environments.
The
soil
partitioning
coefficient
(
Kd)
for
4­
CPA
cannot
be
estimated
from
structural
analysis.
Disposal
of
4­
CPA
treated
water,
after
treatment
of
mung
beans,
should
be
performed
in
compliance
with
all
appropriate
discharge
permits
and
requirements.
By
analogy,
the
phenoxy
herbicides
as
a
class
are
generally
degraded
under
aerobic
conditions
by
microbially
mediated
processes
and
aqueous
photolysis,
and
are
generally
stable
to
hydrolysis,
soil
photolysis,
and
under
anaerobic
conditions.

Conclusions
No
estimated
exposure
concentrations
for
drinking
water
are
presented
in
this
assessment
due
to
the
limited
indoor
use
of
4­
CPA
and
due
to
the
limited
environmental
fate
data.
However,
should
additional
uses
for
4­
CPA
be
considered
EFED
should
be
consulted
to
evaluate
whether
these
uses
may
impact
drinking
water
sources
and
what
additional
data
may
be
needed
for
registration.
