Environmental
Fate
Assessment
of
PHMB
for
the
Reregistration
Eligibility
Decision
(
RED)

August
18,
2004
Case
3122
PC
Code
111801
A.
Najm
Shamim,
Ph.
D.
Office
of
Pesticide
Programs
Antimicrobials
Division
U.
S.
Environmental
Protection
Agency
1200
Pennsylvania
Avenue,
NW
Washington,
DC
20460
Environmental
Fate
Assessment
PHMB
is
stable
hydrolytically
in
the
environment
and
has
a
half­
life
of
more
than
thirty
days.
This
may
be
of
environmental
concern
for
surface
water
contamination.
Studies
for
other
fate
processes
are
not
required
by
and
have
not
been
submitted
to
the
Agency.

PHMB
has
a
half­
life
of
more
than
thirty
days
and
maybe
of
environmental
concern
for
surface
water
contamination.

Hydrolysis:
One
hydrolysis
study
(
MRID
43622301)
was
submitted
to
the
Agency
for
review.
The
study
assessed
the
hydrolytic
stability
of
a
20%
solution
of
PHMB.
Test
solutions
of
PHMB
were
prepared
at
pH
5,
7,
and
9
using
buffers
and
water
adjusted
with
sodium
hydroxide
of
hydrochloric
acid.
Analysis
of
the
test
solutions
by
GPC
and
UV,
following
four
7­
to
9­
day
intervals
for
up
to
thirty
days
in
a
25
°
C
water
bath,
indicated
that
PHMB
is
hydrolytically
stable
at
pH
5,7,
and
9
at
25
°
C.
Additionally,
the
data
show
that
PHMB
has
a
half­
life
of
more
than
thirty
days
(
i.
e.,
<
10
%
total
degradation
in
30
days).
