MEMORANDUM:

May
25,
2005
SUBJECT:
Envivornmental
Fate
Assessment
of
Nuesept
95
(
Azadioxabicyclooctane)
for
the
Reregistration
Eligibility
Decision
(
RED)
Process
From:
A.
Najm
Chamim,
Ph.
D.,
Chemist
Regulatory
Management
Branch
II
Antimimicrobials
Division
(
7510C)

To:
Ben
Chambliss,
Team
Leader
Regulatory
Management
Branch
II
Antimicrobials
Division
(
7510C)

And
Kathryn
Montague,
Science
Coordinator
for
Aza
RED
Risk
Assessment
and
Science
Support
Branch
Antimicrobials
Division
(
7510C)

Thru:
Mark
Hartman,
Chief
Regulatory
Management
Branch
II
Antimicrobials
Division
(
7510C)

Enclosed
is
the
Environmental
Fate
Science
Chapter
on
the
Risk
Assessment
for
Azadioxabicyclooctane
RED.

DP
Barcode:
PC
Codes:
10701,
10702,
and
10703
CAS#:
ENVIRONMENTAL
FATE
AND
TRANSPORT
ASSESSMENT
FOR:
AZADIOXABICYCYCLOOCTANE
EXECUTIVE
SUMMARY:

The
Agency
database
for
risk
assessment
of
Azadioxabicyclooctane
(
mixture
of
three
components)
is
incomplete
as
only
abiotic
aqueous
hydrolysis
study
is
available
for
this
pesticide.
However,
for
the
present
risk
assessment,
we
have
used
Agency's
EPISuite
Program,
which
is
an
estimation
program
of
physical
and
chemical
characteristics
as
well
as
some
fate
and
transport
parameters
of
chemicals.
This
possibly
will
give
a
conservative
fate
assessment
of
azadioxabicyclooctane.

Azadioxabicyclooctane
(
is
a
mixture
of
three
acetals:
5­
hydroxymethoxymethyl­
1­
aza­
3,7­
dioxabicyclo(
3.3.0)
octane
(
28.8%),
(
component
A)
5­
hydroxymethyl­
1­
aza­
3,7­
dioxabicyclo(
3.3.0)
octane
(
16.0%),
(
component
B)
and
5­
hydroxypoly(
methyleneoxy)*
methyl­
1­
aza­
3,7­
dioxabicyclo(
3.3.0)
octane
(
6.2%),
(
component
C)
where
the
polychain
is
extended
as:
74%
C2,
21%
C3,
AND
4%
C4,
AND
1%
C5
(
meaning
from
1
C
to
C5
chain
lengths
of
CH2O
groups
are
added).
EPI
Suite
lacks
estimation
of
the
third
of
the
three
isomers
(
CAS#
56709­
13­
8).

Under
abiotic
conditions,
the
mixture
of
these
acetals
is
hydrolytically
unstable
with
half
life
of
0.347
days
at
pH
5,
1.74
days
at
pH
7
and
approximately
15
days
at
pH
9.
It
is,
therefore,
not
likely
to
be
persistent
in
water.

Components
A
and
B
of
the
mixture
are
likely
to
volatilize
into
the
atmosphere
as
their
vapor
pressures
vary
between
0.0004
to
0.003
mm
Hg.
Component
C
is
likely
to
have
less
volatility
as
the
side
chain
of
CH2O
groups
are
added
into
the
structure.
Estimated
half
lives
in
the
atmosphere
for
components
A
and
B
are
1.2
and
1.4
hours.
Hence
these
two
chemicals
are
not
likely
to
persist
in
the
atmosphere.
Estimated
log
Kow
s
of
components
A
and
B
are
respectively
are
­
2.23
and
­
1.55
(
very
highly
miscible
in
water
and
show
no
tendency
for
dissolving
organic
solvents),
the
mixture
is
not
likely
to
bioaccumulate
in
aquatic
organisms.

MITI
linear
biodegradability
(
modified
linear
biodegradation
method)
for
components
A
and
B
indicates
a
fast
biodegradation
is
highly
probable
in
soils
and
water.
Most
likely
these
pesticides
do
not
pose
a
concern
for
surface
and
ground
water
contamination
APPENDIX
FOR
ENVIRONMENTAL
FATE
CHAPTER
Methodology
and
Results:

Buffered
aqueous
solutions
of
Neusept
95
samples
were
analyzed
for
two
durations:
first
24
hours
and
second
set
for
the
intervals
up
to
33
days.
Possible
degradation
of
Neuspet
95
was
followed
by
the
GC
peak
changes
of
Oxazolidine­
T,
which
was
added
into
the
samples
as
a
reference
material.
The
initial
concentrations
of
the
solutions
were
kept
at
250
µ
g/
ml.
All
test
solutions,
for
the
duration
of
study
were
kept
in
dark,
and
temperature
was
maintained
between
24.9
to
25.1
o
C
For
the
33­
day
study,
samples
were
chromatographically
analyzed
at
the
intervals
of
1,3,
7,
14,
21,
and
33
days.
For
the
short
duration
study
of
24
hours,
the
samples
were
analyzed
at
the
end
of
24
hours.
For
the
24­
hour
short
term
study,
the
percent
recovery
of
Oxazolidine­
T
was:
0.65%
at
pH
5,
19.2%
at
pH
7,
and
28.4%
for
pH
9.
This
indicates
that
at
least
70%
of
the
samples
degraded
at
pH
9
almost
80%
at
pH
7
and
almost
95%
at
pH
5.
For
the
33­
day
study,
at
the
end
of
33
day
duration,
the
percent
recoveries
of
Oxazoldine­
T
were:
2%
at
pH
5,
20.2%
at
pH
7,
and
27.6%
at
pH
9.,
which
are
almost
the
same,
within
the
margin
of
errors,
as
for
the
24­
hour
study
recoveries.
It
is
clear
that
the
degradation
is
more
rapid
under
acidic
conditions
(
pH
5)
and
less
so
at
neutral
(
pH
7)
or
basic
conditions
(
pH
9).
To
ascertain
where
the
degradation
takes
place
in
any
of
the
three
isomers,
degradation
study
was
conducted
in:
a)
unbuffered
solution
of
Oxazolidine­
T
and
b)
unbuffered
solution
of
oxazolidine
in
the
presence
of
0.1%
formalin.
The
solution
(
b)
remained
unchanged
after
twenty
four
hours;
however,
the
unbuffered
solution
(
a)
without
formalin
degraded
gradually
and
percent
recoveries
of
oxazolidine
were
low.
This
possibly
indicate
that
with
the
addition
of
formalin,
the
ring
hydrolysis
of
oxazolidine
was
prevented,
while
the
side
chain
with
CH2O
(
formaldehyde
group)
depolymerized.
The
kinetic
rate
constants
for
the
forward
reactions
(
kf)
and
the
reverse
reaction
(
kr)
were
calculated
as
follows:

pH
kf
kr
pH
kf
kr
5
1.95
0.047
7
0.41
0.109
9
0.436
0.198
The
calculated
half
life
values
from
these
rate
constants
(
assuming
first
order
kinetics
are:
0.347
days,,
1.74
days
and
15
days
taking
into
account
the
forward
reactions
(
degradations)
only.
BIBLIOGRAPHY
MRID#
CITATIONS
430607­
01
John
Cross,
Aqueous
Hydrolysis
of
Neusept
95,
EPL
Bio­
Analytical
Services,
Harrison
IL,
1993
­­­­­­­­­­­­­
EPI
Suite
