UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
April
4,
2006
MEMORANDUM
SUBJECT:
Sodium
cyanide:
Occupational
Exposure
Assessment
and
Recommendations
for
the
Tolerance
Reassessment
Eligibility
Decision
(
TRED)
Document
(
RED
Case
2560)

FROM:
David
Jaquith,
Environmental
Scientist
Reregistration
Branch
4
Health
Effects
Division
THRU:
Susan
Hummel,
Senior
Scientist
Reregistration
Branch
4
Health
Effects
Division
TO:
Rebecca
Daiss,
Risk
Assessor
Reregistration
Branch
4
Health
Effects
Division
Craig
Doty,
Chemical
Review
Manager
Special
Review
and
Reregistration
Division
DP
Barcode(
s):
D318017
PC
Code:
074002
MRID
46648901
1
1.0
Background
and
Purpose
The
attached
document
addresses
occupational
exposures
and
risks
for
sodium
cyanide
oxide
to
support
the
Health
Effects
Division
(
HED)
reregistration
eligibility
decision
(
RED)
document.
A
RED
was
completed
in
September
1994
(
pre
FQPA,
ORE
Chapter
February
28,
1994)
but
the
RED
did
not
consider
the
use
for
fumigation
of
citrus.
A
Phase
IV
review
was
completed
June
19,
1992
and
did
not
consider
the
fumigant
use.

2.0
Products
and
Formulations
Sodium
cyanide
exists
in
two
formulations;
predator
baits
and
for
fumigation
of
citrus
shipped
from
California
to
Arizona.
The
application
rates
are
presented
in
Table
1.
A
more
detailed
summary
of
the
labels
is
presented
in
Appendix
A.

Application
Rates
Table
1:
Sodium
Cyanide
Application
Rates
Scenario
Application
Rate
Fumigation
Time
(
hours)
Fumigation
of
Citrus
Fruit
1
oz/
100ft3
of
Sodium
Cyanide
(
Equivalent
to
6
oz
HCN/
1000
ft3
1
hour
Animal
Baits/
Injectors
91.06
%
sodium
cyanide
per
bait,
up
to
10­
12
units
per
square
mile
NA
Fumigation
Process
Sodium
cyanide
is
registered
in
California
as
Special
local
need
(
SLN
CA­
840006)
for
the
generation
HCN
to
fumigate
citrus
eliminate
red
scab
another
surface
pests
prior
to
shipment
to
Arizona.
It
is
used
as
quarantine
procedure
to
prevent
the
spread
of
these
pests.
Trailers
are
fumigated
with
HCN
using
a
closed
system
in
which
the
appropriate
amount
of
sodium
cyanide
is
mixed
with
concentrated
sulfuric
acid
and
water.
The
trailers
are
fumigated
for
1
hour.
They
are
then
aerated
with
more
than
10
air
changes
for
½
or
1
hour.
The
results
of
an
air
monitoring
are
presented
in
Appendix
B.

Bait
Process
The
use
of
sodium
cyanide
in
bait
products
has
been
discussed
in
the
RED
document
in
September
1994
and
the
ORE
chapter
for
the
review
(
W.
Dang,
February
28,
1994)
and
will
not
be
further
considered
in
this
report.

3.0
Hazard
Identification
Cyanide
is
an
acute
toxicant.
However,
with
the
exception
of
citrus
fumigation
the
Agency
has
relied
on
incidence
data
to
identify
any
hazard
associated
with
use
of
this
compound.
These
data
are
compiled
in
the
following
section.

4.0
Incident
Report
2
Only
5
reports
have
been
submitted
by
USDA
APHIS
concerning
mishaps
with
M­
44
Capsules
containing
sodium
cyanide
since
1992
when
EPA
set
up
the
Incident
Data
System.
None
of
the
mishaps
resulted
in
serious
medical
outcomes.
All
resulted
in
transient
symptoms
which
were
minor
to
moderate.
Poison
Control
Centers
have
tracked
rodenticide
use
of
cyanide
over
the
years
since
1985,
however,
their
system
does
not
specify
the
form
of
the
cyanide
(
e.
g.,
calcium
cyanide,
sodium
cyanide,
or
hydrogen
cyanide).
On
average
Poison
Control
Centers
receive
only
one
report
per
year.
Most
listed
the
outcome
as
not
determined
or,
at
most,
minor
medical
outcome.
(
Jerry
Blondell,
2005)

5.0
Non­
Occupational/
Residential
Exposure
.
This
material
is
not
used
in
the
residential
environment
Label
Requirements
The
end­
use
label
for
fumigation
(
EPA
Reg.
No.
39352­
50001­
AA)
requires
the
following
regarding
exposure
and
worker
protection.

 
Where
there
is
potential
for
dermal
contact,
full
body
personal
protective
equipment
(
PPE)
must
be
worn.
This
includes
solvent­
proof
gloves,
clothing,
hat,
apron,
and
boots.
Vapor­
proof
goggles
are
also
required.

6.1
Non­
Cancer
and
Cancer
Occupational
Exposure
and
Risk
Estimates
Short­/
Intermediate­
Term
and
Long­
Term
Inhalation
Exposure
There
is
potential
for
inhalation
exposure
to
Sodium
cyanide
during
sterilization
and
poststerilization
activities;
however
current
exposure
monitoring
data
are
unavailable.
A
study
was
conducted.
Rather
than
collecting
air
samples
and
measuring
HCN
concentrations
in
an
analytical
lab,
a
continuous
monitor
was
used.

The
current
Occupational
Safety
and
Health
Administration
(
OSHA)
permissible
exposure
limit
(
PEL)
for
hydrogen
cyanide
is
10
ppm
(
11
milligrams
per
cubic
meter
(
mg/
m3))
as
an
8­
hour
time­
weighted
average
(
TWA)
concentration.
The
OSHA
PEL
also
bears
a
"
Skin"
notation,
which
indicates
that
the
cutaneous
route
of
exposure
(
including
mucus
membranes
and
eyes)
contributes
to
overall
exposure.

The
National
Institute
for
Occupational
Safety
and
Health
(
NIOSH)
has
established
a
recommend
exposure
limit
(
REL)
for
hydrogen
cyanide
of
4.7
ppm
(
5
mg/
m3)
as
a
STEL
(
Short
term
exposure
limit,
that
level
at
which
an
unprotected
worker
can
be
exposed
for
15
minutes
without
harm).
NIOSH
also
assigns
a
"
Skin"
notation
to
hydrogen
cyanide.

A
NOAEL
of
65
mg
HCN/
m3
based
on
mortality
in
3
of
10
rats
at
the
LOAEL
of
71
mg/
m3
(
HDT).
Sprague­
Dawley
rats
(
15/
sex/
dose)
were
exposed
to
acetone
cyanohydrin
(
ACH)[
which
is
rapidly
hydrolyzed
to
hydrogen
cyanide
at
physiological
pH]
at
concentrations
of
0,
36,
101,
3
or
204
mg
ACH/
m3
for
6
hours/
day,
5
days/
week,
for
14
weeks.
Adjusted
for
occupational
inhalation
exposure,
the
occupational
is
50
mg/
m3
(
46
ppm).
The
exposures
were
equivalent
to
0,
11,
32,
and
65
mg
HCN/
m3.
The
NOAEL
reported
from
the
study
was
204
mg
ACH/
m3,
corresponding
to
65
mg
HCN/
m3.
This
can
be
estimated
to
correspond
to
a
daily
dose
of
15
mg
cyanide/
kg
BW/
day.
However,
in
a
similar
4­
week
inhalation
study
at
an
average
ACH
concentration
of
211
mg/
m3
(
67
mg
hydrogen
cyanide/
m3),
no
systemic
effects
were
observed,
except
on
the
first
day
of
exposure,
when
the
concentrations
in
the
chamber
fluctuated
and
reached
values
of
225
mg
ACH/
m3
(
71
mg
hydrogen
cyanide/
m3)
at
which
dose
3
out
of
10
animals
died.
The
dose­
response
relationship
for
cyanide
is
thus
very
steep
for
inhalation
exposure
(
Dykstra,
2006).
The
NOAEL/
LOAEL
for
the
inhalation
endpoint
is
based
on
the
acute
effect
of
mortality
for
hydrogen
cyanide.
The
MOE
is
based
on
the
uncertainty
factor
of
30X
(
3x
interspecies
factor
and
10x
intraspecies
factor).
The
traditional
interspecies
factor
of
10X
is
reduced
to
3X
since
the
doses
are
expressed
as
air
concentrations
and
the
pharmacokinetics
is
assumed
similar
between
animals
and
humans.
The
interspecies
factor
of
3x
is
considered
sufficient
to
account
for
only
pharmacodynamic
differences
between
animals
and
humans.

While
a
NOAEL
of
65
mg/
m3
(
60
ppm)
has
been
established,
this
was
based
on
a
continuous
6
hour
exposure
for
14
weeks.
Adjusted
for
occupational
exposure,
the
inhalation
exposure
endpoint
for
hydrogen
cyanide
is
50
mg/
m3
(
46
ppm).
It
is
obvious
from
the
study
outlined
in
Appendix
B
that
any
exposure
in
the
workplace
is
transient
in
nature
and
does
not
match
the
conduct
of
the
toxicology
study.
The
peak
15
minute
STEL
from
that
study
was
0.4
ppm
(
0.36
mg/
m3).
Using
this
value
results
in
a
MOE
of
115
even
if
is
based
on
a
very
short
term
exposure.
It
can
reasonably
be
considered
that
the
fumigation
of
citrus
with
NaCN
offers
little
in
the
area
of
risk.

Cancer
Risk
There
is
no
cancer
concern
for
this
chemical.
No
Q1
*
or
MOE
for
cancer
has
been
established.

Short­/
Intermediate­/
Long­
Term
Dermal
Exposure
and
Risk
Since
HCN
is
a
gas
used
in
outdoor
environment,
there
is
no
dermal
risk
from
the
gas
itself.
Potentially
there
could
be
a
risk
from
the
solid
salt.
However
incidence
data
does
not
support
a
quantified
risk
assessment
for
dermal
exposure
7.0
Risk
Summary
HCN
is
an
acute
toxicant.
The
very
low
level
incidences
indicate
that
risk
from
this
chemical
is
minimal
8.0
References
1988
NIOSH
PEL
Project
Documentation.
http://
www.
cdc.
gov/
niosh/
pel88/
75­
56.
html
4
American
Conference
of
Governmental
Industrial
Hygienists.
TLVs
and
BEIs
Based
on
the
Documentation
of
the
Threshold
Limit
Values
for
Chemical
Substances
and
Physical
Agents
and
Biological
Exposure
Indices.
Signature
Publications.
2004.

EPA
Reregistration
Eligibility
(
RED)
Sodium
Cyanide
EPA
738­
R­
94­
020,
September
1994.

Memorandum
from
W.
Dang
(
OREB/
HED)
to
J.
Smith
(
CCB/
HED)
titled
"
Occupational
and
Residential
Exposure
Assessment
and
Recommendations
for
the
Reregistration
Eligibility
Document
for
Sodium
Cyanide",
dated
February
28,
1994.

Email
from
J.
Blondell
(
CEB/
HED),
dated
May
3,
2005.
Appendix
A.
Summary
of
Labels
For
Sodium
Cyanide
Products.

EPA
Reg
No.
Use
Comments
39352­
50001­
AA
Citrus
Fumigation
Ventilation
to
5
ppm,
HCN
gas
monitors
required,
cloth
or
disposable
garments
and
waterproof
gloves
are
required,
goggles
or
face
shield
required,
two
persons
are
required
to
be
present,
temperature
not
less
than
60
degrees
nor
more
than
80
degrees,
restricted
area
of
at
least
20
feet
around
trailer,
posting
required,
roll
up
doors
are
prohibited,
1
oz
sodium
cyanide
per
100
ft
³
.

35978­
1
Predator
Bait
56228­
32
Predator
Bait
39508­
1
Predator
Bait
56228­
15
Predator
Bait
1308­
8
Predator
Bait
39260­
1
Predator
Bait
35975­
2
Predator
Bait
M­
44
capsules,
Certified
Applicators
only,
posting
required.
Appendix
B.

Citation
Reference:
Krieger,
R.
(
1999)
"
Monitoring
of
Personal
and
Work
Site
Air
for
Hydrogen
Cyanide
Resulting
from
Fumigation
of
Citrus":
Final
Draft
Report.
Project
Number:
HCN/
3/
99.
Unpublished
study
prepared
by
University
of
California,
Riverside.
40
p.
MRID
46648901
INTRODUCTION
Sodium
cyanide
is
registered
in
California
as
Special
local
need
(
SLN
CA­
840006)
for
the
generation
HCN
to
fumigate
citrus
eliminate
red
scab
another
surface
pests
prior
to
shipment
to
Arizona.
It
is
used
as
quarantine
procedure
to
prevent
the
spread
of
these
pests.
It
is
used
to
fumigate
sealed
trailers,
which
are
then
aerated.
These
procedures
are
described
in
more
detail
below.

DESCRIPTION
OF
STUDY
The
study
was
conducted
in
February
and
March
of
1999.
Air
concentrations
of
cyanide
were
measured
in
the
breathing
zone
of
the
applicators
and
in
the
ambient
air.
The
trailers
were
treated
at
a
rate
of
1
ounce
of
sodium
cyanide
per
100
ft3
(~
6
ounces
of
HCN
per
1000
ft3)

Trailers
are
fumigated
with
HCN
using
a
closed
system
in
which
the
appropriate
amount
of
sodium
cyanide
is
mixed
with
concentrated
sulfuric
acid
and
water.
The
trailers
are
fumigated
for
1
hour.
They
are
then
aerated
with
more
than
10
air
changes
for
½
or
1
hour.
In
February
one
trailer
was
fumigated
3
times
and
additional
5
trucks
fumigated
that
same
day.
In
March
one
rig
was
fumigated
prior
to
the
start
of
monitoring.
This
trailer
was
later
fumigated
and
ventilated
4
more
times.
In
addition
another
trailer
was
fumigated
and
ventilated
3
times.
A
total
of
10
fumigation/
ventilations
were
monitored
during
the
study.
Each
fumigation
lasted
for
1
hour.

Airborne
HCN
concentrations
were
measured
using
Safelog
100
datalogging
monitor.
The
monitors
were
zeroed
using
a
compressed
gas
cylinder
and
calibrated
using
a
commercially
prepared
10
ppm
standard
of
HCN
in
nitrogen.
The
flow
rate
was
400
mL
per
minute.
One
monitor
was
carried
in
the
breast
pocket
of
the
fumigator.
One
ambient
monitor
was
located
50
feet
from
the
trailer,
somewhat
farther
than
the
20
foot
buffer
zone
required
by
the
label.
Additional
area
monitors
were
located
downwind
at
distances
of
50,
100,
and
200
feet
from
the
trailer.
The
high
alarm
for
HCN
is
10
ppm.
The
high
alarms
for
STE
and
TWA
are
each
4.7
ppm.

Following
fumigation
the
trailers
were
ventilated
for
1
hour
through
a
ventilation
stack
with
a
height
of
20
feet
6
inches
at
a
rate
of
800
ft3/
minute.
Stack
diameter
was
3
inches.
The
HCN
levels
of
the
personal
monitor
worn
by
the
fumigator
are
presented
in
Table
B1.
Exposure
was
low
and
no
alarms
were
noted
at
any
time.
Peak
1­
minute
levels
were
4.7
and
5.6
for
the
two
days.
The
peak
STEL
was
0.4
for
each
of
the
days
Table
B1.
Gas
Detection
Report
for
the
Fumigator
(
Monitor
1)
Date
Time
Start­
Stop
Number
of
Trailers
HCN
Levels
(
ppm)

Peak
(
1
min)
Average
Peak
STEL
1
(
15
min)
TWA
2
Feb.
18,
1999
10:
27
am
to
5:
31
PM
3
4.7
0.0
0.4
0.0
Mar.
3,
1999
9:
00
am
to
8:
19
PM
7
5.6
0.0
0.4
0.0
1
The
Short
Term
Exposure
Limit
(
STEL)
to
which
an
unprotected
worker
may
be
exposed.
2
The
time­
weighted
average
(
TWA)
is
the
average
air
concentration
taken
over
an
eight­
hour
period.

The
results
of
the
ambient
air
monitoring
are
presented
in
Table
B2.
The
TWAs
were
all
zero.
The
peak
15
minute
STEL
ranged
from
0
to
0.6.
The
latter
was
judged
to
be
the
result
of
displacement
of
a
sunshade
during
monitoring.

Table
B2.
Ambient
Air
Monitoring
Results
Monitor
No.
Month
Distance
from
Trailer
(
ft)
Peak
HCN
Level
(
1
min)
Average
Peak
STEL
(
15
min)
TWA
2
February
50
2.3
0.0
0.0
0.0
3
February
100
0.5
0.0
0.0
0.0
4
February
200
0.3
0.0
0.0
0.0
5
February
45
5.9
0.0
0.3
0.0
2
March
50
2.2
0.0
0.0
0.0
3
March
100
1.2
0.0
0.0
0.0
4
March
200
0.9
0.0
0.6
0.0
5
March
45
1.0
0.0
0.1
0.0
