Document ID: EPA-HQ-OPP-2005-0123-0135
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-03-29T05:00Z

UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
DATE:
March
10,
2006
SUBJECT:
Methyl
Bromide:
Phase
5
Health
Effects
Division
(
HED)
Human
Health
Risk
Assessment
For
Commodity
Uses.
PC
Code:
053201,
DP
Barcode:
D304623
FROM:
Jeffrey
L.
Dawson,
Chemist/
Risk
Assessor
Elizabeth
Mendez,
Ph.
D.,
Toxicologist/
Risk
Assessor
Reregistration
Branch
1
Health
Effects
Division
(
7509C)

TO:
Steven
Weiss,
Chemical
Review
Manager
Special
Review
&
Reregistration
Division
(
7508C)

Based
on
the
information
received
in
the
Phase
3
comment
period,
the
Agency
has
developed
a
revised
Phase
5
assessment
for
methyl
bromide.
However,
the
scope
of
this
current
assessment
has
been
strictly
limited
by
comparison
to
the
Phase
3
assessment
(
see
D316326
at
www.
Regulations.
gov
under
the
methyl
bromide
docket
EPA­
HQ­
OPP­
2005­
0123)
as
it
addresses
only
those
uses
with
food
tolerances
as
established
in
the
40CFR
while
D316326
considered
all
other
methyl
bromide
use
patterns
as
well
(
e.
g.,
pre­
plant
soil
fumigation).
The
scope
of
the
assessment
was
modified
to
allow
for
the
uses
with
tolerances
to
be
evaluated
in
a
timely
manner
in
accordance
with
the
schedule
required
by
the
Food
Quality
Protection
Act
tolerance
reassessment
process.
The
Agency
is
also
engaged
in
an
ongoing,
systematic
analysis
of
pre­
plant
soil
fumigants
in
order
to
address
the
remaining
uses.
These
revised
soil
fumigant
assessments
to
be
completed
later
this
year.
[
Note:
For
efficiency,
all
non­
food
uses
of
methyl
bromide
(
e.
g.,
residential)
will
also
be
included
in
the
upcoming
soil
fumigant
cluster.]

Much
of
the
basic
data
and
calculations
upon
which
this
assessment
is
based
remain
unchanged
from
D316326.
Since
the
bulk
of
the
basic
information
has
not
been
altered,
readers
may
refer
to
the
original
Phase
3
Risk
Assessment
(
D316326)
for
the
underlying
information
as
it
has
not
been
repeated
in
this
document.
However,
key
new
sources
of
information
and
methods
that
have
been
considered
include:
a
recently
submitted
inhalation
developmental
neurotoxicity
study
in
rats,
comments
pertaining
to
the
inputs
used
for
calculating
exposures
to
bystanders
from
commodity
uses
(
e.
g.,
USDA/
PPQ
provided
information
that
allowed
port
facility
fumigation
event
modeling
to
be
significantly
refined),
and
an
upgrade
of
the
PERFUM
model
was
used
to
calculate
the
potential
for
bystander
risks.
In
the
previous
assessment,
the
ISCST3
model
was
used.
It
should
also
be
noted
that
slight
modifications
to
the
dietary
and
drinking
water
elements
of
this
assessment
have
also
been
completed.

The
recently
submitted
information
allowed
the
Agency
to
reduce
the
uncertainty
factor
used
for
the
bystander
assessments
from
300
to
30
based
on
the
inhalation
developmental
neurotoxicity
study,
use
8
hour
HECs
(
Human
Equivalent
Concentrations)
to
address
bystander
exposures
that
more
correctly
reflect
the
anticipated
exposure
patterns,
and
use
the
PERFUM
model
which
has
recently
been
upgraded
with
capabilities
for
addressing
commodity
and
other
non­
field
based
exposure
scenarios.
The
upgraded
PERFUM
model
(
V2.1.2)
is
available
at
http://
www.
sciences.
com/
perfum/
index.
html.
Version
2.1.2
of
PERFUM
will
eventually
be
placed
on
the
Agency's
website
along
with
the
older
Version
1.1
http://
www.
epa.
gov/
opphed01/
models/
fumigant/.
HUMAN
HEALTH
RISK
ASSESSMENT
Methyl
bromide
U.
S.
Environmental
Protection
Agency
Office
of
Pesticide
Programs
Health
Effects
Division
(
7509C)
Jeffrey
L.
Dawson,
Chemist/
Risk
Assessor
Elizabeth
Mendez,
Ph.
D.,
Toxicologist/
Risk
Assessor
Date:
March
10,
2006
HUMAN
HEALTH
RISK
ASSESSMENT
Methyl
bromide
Risk
Assessment
Team:

Risk
Assessor:
Jeffrey
L.
Dawson
Elizabeth
Mendez,
Ph.
D.

Dietary
Risk:
Felicia
Fort
Michael
Metzger
Product
and
Residue
Chemistry:
Christine
Olinger
Michael
Metzger
Occupational
and
Residential
Exposure:
Jeffrey
L.
Dawson
Epidemiology:
Jerome
Blondell,
MPH,
Ph.
D.

Toxicology:
Byong­
Han
Chin,
Ph.
D.
Elizabeth
Mendez,
Ph.
D.

Drinking
Water
Estimates:
Faruque
Khan
1.0
Executive
Summary
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1
2.0
Ingredient
Profile
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5
2.1
Structure
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Nomenclature
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6
2.2
Physical
and
Chemical
Properties
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7
3.0
Metabolism
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7
3.1
Description
of
Primary
Crop
Metabolism
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7
3.2
Description
of
Livestock
Metabolism
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7
3.3
Description
of
Rat
Metabolism
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7
4.0
Hazard
Assessment
and
Characterization
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8
4.1
Hazard
Characterization
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8
4.1.1
Database
Summary
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8
4.1.2
Endpoints
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8
4.1.3
Dose­
response
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9
4.1.3.1
Inhalation
Exposure
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9
4.1.3.2
Dietary
Exposure
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12
4.1.3.3
Dermal
Exposure
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13
4.1.3.4
Classification
of
Carcinogenic
Potential
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13
4.1.4
Endocrine
Disruption
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13
4.2
Uncertainty
Factors
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14
4.3
Summary
of
Toxicological
Endpoint
Selection
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14
5.0
Public
Health
Data
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16
6.0
Non­
Occupational
Exposure
Assessment
and
Characterization
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17
6.1
Residential
Bystander
Exposure
and
Risk
Estimates
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17
6.1.1
Bystander
Exposures
And
Risks
From
Known
Sources
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19
6.1.1.1
Methods
Used
To
Calculate
Bystander
Exposures
And
Risks
From
Known
Sources
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19
6.1.1.2
Bystander
Exposures
And
Risks
From
Known
Sources
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30
6.1.2
Ambient
Bystander
Exposure
From
Multiple
Regional
Sources
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45
6.1.2.1
Exposures
From
Regionally
Targeted
Non­
Point
Source
Ambient
Air
Monitoring
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46
6.1.2.2
Exposures
From
Urban
Background
Ambient
Air
Monitoring
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50
6.2
Bystander
Risk
Characterization
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53
6.3
Residue
Profile
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55
6.4
Acute
and
Chronic
Food
Dietary
Exposure
and
Risk
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56
6.5
Water
Exposure/
Risk
Pathway
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57
7.0
Aggregate
Risk
Assessment
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58
7.1
Acute
and
Chronic
Aggregate
Risk
Assessments
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58
8.0
Cumulative
Risk
Assessment
and
Characterization
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59
9.0
Occupational
Exposure
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60
9.1
Commodity
Fumigations
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60
9.2
Industrial
Fumigations
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61
10.0
Data
Needs
and
Label
Requirements
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62
10.1
Toxicology
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62
10.2
Residue
Chemistry
.
.
.
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.
.
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.
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.
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.
62
10.3
Occupational
and
Residential
Exposure
.
.
.
.
.
.
.
.
.
.
.
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62
Appendices
Appendix
A:
Toxicity
Profile
Appendix
B:
Hazard
Assessment
Array
Appendix
C:
Bibliography
Of
MeBr
Exposure
Data
Appendix
D:
Summary
Data
sheets
For
Commodity
&
Industrial
Fumigation
Events
Appendix
E:
Analysis
Of
Monitoring
Data
For
Commodity
&
Industrial
Facility
Fumigations
Appendix
F:
Downwind
MeBr
Risk
Estimates
Calculated
With
PERFUM
For
Commodity
Uses
Appendix
G:
Summary
Data
sheets
For
Ambient
Monitoring
Data
1
1.0
Executive
Summary
The
Health
Effects
Division
(
HED)
of
EPA's
Office
of
Pesticide
Programs
has
evaluated
the
methyl
bromide
database
and
conducted
a
human
health
risk
assessment
for
the
reregistration
of
the
commodity
uses
of
the
chemical.
[
Note:
Risks
for
other
registered
uses
(
e.
g.,
pre­
plant
soil
treatments)
will
be
addressed
in
a
separate
document
later
this
year.]
This
assessment
begins
phase
5
of
the
6
phase
public
participation
process.
A
summary
of
the
key
areas
of
this
assessment
are
provided
below.
The
attached
appendices
contain
additional
information
that
can
be
used
to
expand
upon
and
characterize
the
risks
presented
in
this
document.

Methyl
bromide
is
a
broad­
spectrum
fumigant
that
can
be
used
as
an
acaricide,
antimicrobial,
fungicide,
herbicide,
insecticide,
nematicide,
and
vertebrate
control
agent.
The
most
prevalent
use
pattern
is
as
a
soil
fumigant;
however,
it
is
also
used
as
a
structural
fumigant
and
post
harvest
treatment
of
commodities.
Methyl
bromide
application
methods
and
equipment
vary
depending
upon
the
setting.
Under
the
accords
of
the
Montreal
protocol,
methyl
bromide
is
scheduled
for
phase
out;
however,
critical
use
exemptions
will
still
be
available
under
special
circumstances.

Acutely,
methyl
bromide
is
a
low
to
moderate
toxicant
via
the
oral
and
inhalation
routes
of
exposure
(
Toxicity
Categories
II
and
IV,
respectively).
In
contrast,
methyl
bromide
is
highly
toxic
via
both
dermal
and
ocular
routes
of
exposure
(
Toxicity
Category
I).
Neurotoxicity
is
the
major
hazard
concern
for
inhalation
exposure,
with
neurotoxic
effects
seen
throughout
the
data
base
in
all
tested
species
of
animals.
Both
acute
and
90­
day
inhalation
neurotoxicity
studies
in
rats
showed
evidence
of
neurotoxic
effects
characterized
by
decreased
activity,
tremors,
ataxia
and
paralysis.
Two
subchronic
studies
showed
dogs
to
be
the
most
sensitive
species
to
the
neurotoxic
effects
of
methyl
bromide.
Neurotoxic
effects
were
also
seen
in
the
chronic/
carcinogenicity
inhalation
study
in
mice
(
ataxia,
limb
paralysis,
degenerative
changes
in
the
cerebellum)
and
in
the
developmental
inhalation
study
in
rabbits
(
lethargy,
right
side
head
tilt,
ataxia).
Risk
assessment
endpoints
for
the
general
population
were
based
primarily
on
neurotoxic
effects.

For
acute
inhalation
risk
assessments,
the
developmental
rabbit
study
was
selected
since
the
fetal
effects
are
presumed
to
occur
after
one
exposure.
In
the
case
of
short
and
intermediate
risk
assessments,
two
subchronic
inhalation
toxicity
studies
in
dogs
were
assessed
together
for
endpoint
selection.
The
chronic/
carcinogenic
inhalation
study
in
rats
was
selected
for
long
term
inhalation
risk
assessment.
A
NOAEL
was
not
identified
in
this
study.
Thus,
a
LOAEL
based
on
nasal
lesions
with
basal
cell
hyperplasia
was
used
as
the
point
of
departure
(
POD).
Consequently,
a
3x
uncertainty
factor
was
applied
for
the
LOAEL
to
NOAEL
extrapolation.

An
acute
dietary
endpoint
applicable
to
the
U.
S.
general
population
was
chosen
from
the
acute
inhalation
neurotoxicity
study
in
rats.
The
endpoint
of
concern
identified
in
this
study
is
neurotoxicity
(
decreased
activity
and
alertness,
decreased
rears,
decreased
motor
activity,
increased
piloerection,
and
decreased
body
temperature).
These
effects
resulted
from
a
single,
6­
hour
dosing
period,
and
are
therefore
appropriate
for
acute
(
one­
day)
risk
assessments.
Developmental
effects
were
the
basis
for
acute
dietary
risk
assessments
for
women
of
child­
bearing
age
(
females
13­
50
years
of
age).
Effects
seen
in
the
developmental
inhalation
toxicity
study
in
rabbits
included
malformations
(
agenesis
of
the
gall
bladder
and
increased
incidence
of
fused
sternebrae)
at
exposure
levels
that
also
caused
maternal
toxicity.
The
chronic
dietary
endpoint
was
selected
from
an
oral
rat
chronic/
carcinogenicity
study
in
which
animals
2
were
dosed
with
micro
encapsulated
MeBr.
In
this
study,
MeBr
exposure
elicited
decreases
in
body
weight
gain,
body
weight,
and
food
consumption.
It
is
noteworthy
that
these
effects
are
less
severe
than
those
reported
in
the
chronic/
carcinogenicity
study
conducted
via
the
inhalation
route,
thus
suggesting
that
MeBr
toxicity
is
greater
via
the
inhalation
route
than
the
oral
route
of
exposure.

Since
clear
NOAELs
were
identified
for
all
studies
used
for
endpoint
selection,
and
their
dose
response
was
well
defined,
HED
determined
that
the
special
FQPA
factor
could
be
reduced
to
1x.
The
selected
points
of
departure
(
PODs)
will
not
underestimate
the
risk.
In
addition,
the
results
of
a
recently
submitted
developmental
neurotoxicity
study
also
supports
this
conclusion.

Methyl
bromide
has
been
responsible
for
a
number
of
incidents
involving
large
clusters
of
people.
The
need
for
Hazmat
teams,
decontamination,
and
medical
care
make
these
cases
significant,
even
though
symptoms
are
often
minor.
Methyl
bromide
exposure
has
caused
symptoms
such
as
headache,
malaise,
weakness,
difficulty
breathing
(
dyspnea),
convulsions,
and
severe
skin
burns
in
many
of
these
incidents.
Incidents
have
been
associated
with
faulty
containers
and
application
equipment.
Methyl
bromide
has
also
been
responsible
for
a
significant
number
of
deaths,
most
involving
individuals
not
directly
involved
in
the
application.
Factors
identified
in
the
more
serious
cases
included
lack
of
training
and
proper
protective
equipment,
fumigation
of
tree
holes,
inadvertent
exposure
to
leaking
structures
or
structures
with
unexpected
conduits
or
openings,
and
working
in
soil
or
other
areas
where
residues
remained.

Releases
of
fumigants
such
as
methyl
bromide
can
be
categorized
in
two
distinct
manners
that
include
addressing
bystander
exposures
from
single
known
application
sites
such
as
stacks
from
a
commodity
fumigation
and
also
by
evaluating
available
ambient
air
monitoring
data
where
residues
could
result
from
many
applications
within
a
region.
Risks
from
known
single
sources
were
evaluated
using
monitoring
data
and
modeling
techniques.
Risks
from
ambient
air
were
evaluated
solely
on
the
basis
of
monitoring
data
from
California.

When
considering
the
potential
risks
of
bystanders
for
single
application
sites
that
encompass
single
known
sources
(
e.
g.,
point
sources
such
as
stacks
from
commodity
chambers)
it
is
also
important
to
understand
that
this
has
been
an
iterative
process
that
reflects
the
evolution
of
HED's
methodologies
for
calculating
the
potential
risks
associated
with
fumigant
use.
There
are
a
number
of
volatility
studies
which
quantified
methyl
bromide
emissions
from
facilities.
However,
these
data
are
limited
in
their
utility
because
they
provide
results
only
for
the
specific
conditions
under
which
the
experiment
was
conducted.
Therefore,
to
provide
more
flexibility,
ISCST3
or
the
Industrial
Source
Complex:
Short­
Term
Model
(
http://
www.
epa.
gov/
scram001/)
was
also
used
to
develop
risk
estimates
for
bystanders
associated
with
methyl
bromide
commodity
uses
in
the
previous
risk
assessment
(
see
the
methyl
bromide
docket
EPAHQ
OPP­
2005­
0123
at
www.
Regulations.
gov
under
D316326).
In
addition,
in
response
to
HED's
ISCST3
methodologies
for
assessing
pre­
plant
soil
fumigants,
three
separate
air
models
based
on
ISCST3
that
incorporate
weather
and
emissions
variability
over
time
(
PERFUM,
FEMS,
SOFEA)
were
reviewed
by
the
FIFRA
SAP
(
http://
www.
epa.
gov/
scipoly/
sap/
2004/
index.
htm
­
see
Aug.
&
Sept.).
The
SAP
concluded
that
each
of
the
three
models
could
provide
scientifically
defensible
results
for
risks
associated
with
soil
fumigation
practices
and
also
suggested
modifications
and
additional
data
that
could
further
refine
risk
estimates.
Since
the
release
of
the
previous
assessment,
the
PERFUM
model
has
been
modified
to
be
able
to
calculate
risk
estimates
for
commodity
and
other
non­
field
uses.
PERFUM
is
a
refinement
because
it
allows
users
to
develop
an
understanding
of
the
distributions
of
potential
bystander
exposures
around
the
perimeter
of
a
treatment
facility
or
structure
and
thus
more
fully
characterize
the
1aPAD/
cPAD
=
acute/
chronic
Population
Adjusted
Dose
=
Acute
or
Chronic
RfD
FQPA
Safety
Factor
3
range
of
risks
resulting
to
bystanders
from
commodity
treatments
This
is
a
modification
from
the
previously
completed
assessments
because
ISCST3
was
used
in
a
deterministic
approach
and
PERFUM,
or
other
similar
tools
were
not
available.
ISCST3
is
an
integral
part
of
the
PERFUM
model.
The
basic
physics
and
code
of
ISCST3
remain
unchanged.
PERFUM
essentially
provides
ISCST3
with
daily
meteorological
data
over
the
selected
5
years
as
well
as
user
defined
emissions
inputs.
PERFUM
then
uses
this
information
to
create
distributional
outputs
for
receptor
locations
around
the
treated
structure.

In
this
assessment,
monitoring
data
and
the
updated
PERFUM
model
were
used
to
calculate
bystander
risks.
The
results
indicate
that
cute
risks
are
of
concern
based
on
the
monitoring
data
for
locations
in
proximity
to
treated
structures.
In
many
situations,
PERFUM
predicted
buffer
distances
are
1440
meters
which
is
the
maximum
distance
that
the
PERFUM
model
will
predict
even
at
lower
percentiles
of
exposure
(
e.
g.,
50th).
However,
in
other
situations,
PERFUM
predicts
that
buffer
distances
can
be
in
proximity
to
the
treated
structure
or
chamber
even
at
the
highest
percentiles
of
exposure.
It
appears
that
the
APHIS
PPQ
(
i.
e.,
a
venting
tube
placed
on
the
ground
in
secured
areas)
and
portable
stack
aeration
approaches
consistently
have
the
lowest
buffer
distances
associated
with
them.
No­
stack
situations
(
e.
g.,
opening
a
door
on
a
warehouse
or
Seavan)
tend
to
have
the
highest
buffer
distances
associated
with
them.
It
is
clear
that
many
different
factors
can
impact
the
air
concentrations
(
and
hence,
risks)
in
proximity
to
structures
and
chambers
that
are
used
for
commodity
treatments
with
methyl
bromide.

With
regard
to
exposure
from
ambient
air,
HED
has
reached
similar
conclusions
to
that
of
CDPR
in
that
there
are
no
imminent
health
concerns
from
methyl
bromide
levels
in
ambient
air.
In
this
analysis,
HED
considered
both
targeted
monitoring
data
from
high
agricultural
use
areas
during
the
season
of
use
(
i.
e.,
known
as
CARB
data)
and
data
meant
to
establish
background
concentrations
in
urban
environments
(
i.
e.,
known
as
TAC
data).
Exposures
for
all
durations
ranging
from
acute
to
chronic
were
considered
from
MeBr
levels
in
ambient
air.
Regardless
of
the
data
considered,
risks
do
not
exceed
HEDs
level
of
concern
for
acute,
short­
and
intermediate­
term
exposures.
HED
calculated
chronic
exposure
based
on
CARB
data
using
a
rangefinder
approach
because
monitoring
data
specifically
meant
to
establish
chronic
exposure
levels
in
high
use
areas
were
not
available.
Based
on
this
approach,
in
some
cases,
chronic
risks
exceed
HEDs
level
of
concern;
however,
HED
believes
that
these
results
do
not
pose
an
imminent
health
concern
to
the
general
public
due
to
the
nature
of
the
rangefinder
calculations
and
the
representativeness
of
the
data
related
to
the
commodity
uses
of
methyl
bromide.
The
results
do
however
indicate
a
need
for
additional
monitoring
data
for
this
scenario.
Chronic
exposures
in
urban
environments
were
not
of
concern.
Finally,
it
should
be
noted
that
some
of
the
urban
monitoring
stations
are
located
in
the
same
communities
where
major
commodity
fumigations
occur
(
e.
g.,
Long
Beach
CA)
which
should
be
considered
in
the
interpretation
of
the
results.

Acute
and
chronic
dietary
risks
for
MeBr
from
food
intake
for
the
general
U.
S.
population
and
various
population
subgroups
was
also
estimated.
For
all
included
commodities,
the
acute
and
chronic
risks
do
not
exceed
HED's
level
of
concern
(
<
100%
aPAD1)
for
the
general
U.
S.
population
and
all
population
subgroups.
4
Estimated
drinking
water
concentrations
for
MeBr
were
modeled
using
PRZM­
EXAMS
(
Pesticide
Root
Zone
Model
­
Exposure
Analysis
Modeling
System)
for
surface
water;
however,
groundwater
concentration
was
not
estimated
for
MeBr
because
the
Environmental
Fate
and
Effects
Division
(
EFED)
does
not
currently
perform
vapor
phase
transport
of
fumigants
to
groundwater.
The
maximum
concentration
for
ground
water,
based
on
the
data
base
of
pesticides
in
groundwater,
is
used
for
both
acute
and
chronic
assessments.

For
the
acute
and
chronic
dietary
(
food
and
water
only)
aggregate
assessments,
HED
has
no
aggregate
risks
of
concern.
The
dietary
and
drinking
water
exposures
alone
do
not
exceed
the
appropriate
population
adjusted
doses.
However,
residential
risks
exceed
HED's
level
of
concern
for
several
scenarios;
therefore,
additional
exposures
from
dietary
intake
would
result
in
even
greater
aggregate
risks
of
concern.
Therefore,
aggregate
risks
for
scenarios
other
than
dietary
intake
and
drinking
water
were
not
considered.

HED
used
an
extensive
worker
monitoring
database
for
the
evaluation
of
the
risks
associated
with
various
occupational
tasks
associated
with
commodity
treatments
that
include
the
following:
commodity
applications
(
applicator,
aerator,
forklift
drivers
and
line
workers);
and
industrial
applications
(
remote
applicators,
cannister
openers
and
aerators).
Overall,
data
indicate
that
worker
risks
exceed
HED's
level
of
concern
for
the
majority
of
scenarios
considered,
even
when
appropriate
mitigation
measures
were
taken
(
e.
g.,
respirators).
Chronic
exposures
were
of
concern
for
all
scenarios,
regardless
of
whether
or
not
respiratory
protection
of
any
sort
is
used.
However,
the
number
of
chronically
exposed
workers
is
expected
to
be
rather
small
in
comparison
to
those
who
are
exposed
for
shorter
durations.
5
2.0
Ingredient
Profile
MeBr
is
a
broad­
spectrum
fumigant
chemical
that
can
be
used
as
an
acaricide,
antimicrobial,
fungicide,
herbicide,
insecticide,
nematicide,
and
vertebrate
control
agent.
Most
use
is
on
terrestrial
non­
food
use
sites
but
other
commonly
treated
sites
include
indoor
food
and
non­
food
use
sites,
residential
settings,
and
commercial/
industrial
facilities.
Approximately
47
million
total
pounds
were
applied
annually
during
the
years
1990
through
1999.
Pre­
plant
field
uses
in
agriculture
accounted
for
about
41
million
pounds
per
year
while
post­
harvest
commodity
treatments
accounted
for
another
4
million
pounds
and
structural
fumigations
accounted
for
2.3
million
pounds
per
year.
A
2001
update
to
that
analysis
for
pre­
plant
soil
fumigation
of
selected
crop
(
tomatoes,
strawberries,
onions,
and
selected
tree
fruits
and
melons)
for
8
major
use
states
(
CA,
FL,
NC,
SC,
MI,
GA,
WA,
OH)
indicates
that
2001
use
(
22.4
million
pounds)
was
40
percent
of
the
1991
baseline
(
56.2
million
pounds)
for
those
crops
and
locations.
Strawberries,
eggplant,
peppers,
and
tomatoes
are
the
crops
with
the
highest
percentage
of
their
overall
acreage
treated.
The
average
annual
percent
crop
treated
for
those
crops,
respectively,
were
54,
43,
17,
and
13
percent
while
the
maximum
percent
crop
treated,
respectively,
for
those
crops
was
70,
75,
19,
and
21
percent.
Most
crops
were
treated
once
per
year
and
the
average
application
rate
for
crops
(
lb
ai/
acre/
application)
ranged
from
a
low
of
5
lb
ai/
acre
on
cotton
to
a
high
of
260
lb
ai/
acre/
application
on
cucumbers.
Common
pre­
plant
agricultural
field
uses
for
various
crops
have
maximum
application
rates
that
range
from
the
200
lb
ai/
acre/
application
range
up
to
around
430
lb
ai/
acre/
application
(
e.
g.,
5785­
4
and
5785­
42).
Very
high
rates
such
as
the
890
lb
ai/
acre/
application
are
generally
reserved
for
more
specialized
applications
such
as
tree
planting
scenarios.
The
treatment
of
perishable
goods
used
2,290,000
lb/
year
while
durable
good
treatments
and
quarantine
uses
accounted
for
1,373,000
and
530,000
lb/
year,
respectively.
The
use
of
MeBr
as
a
structural
fumigant
is
waning
because
of
the
availability
of
alternatives.
Annual
use
averaged
2,300,000
lb/
year
with
facilities
and
food
handling
establishments
accounting
for
755,000
lb/
year;
residential/
museum/
antique
treatments
accounting
for
1,373,000
lb/
year;
and
transport
vehicles
accounting
for
another
160,000
lb/
year.
Application
rates
for
commodity
fumigations
can
range
from
1
to
20
lb
ai/
1000
ft3
but
most
perishable
goods
that
have
an
established
food
tolerance
under
40CFR
are
in
the
1
to
4
lb
ai/
1000
ft3
range
(
e.
g.,
grapes).
Likewise,
structural
fumigations
are
in
the
1
to
9
lb
ai/
1000
ft3
range.
For
examples
of
methyl
bromide
labels,
see
http://
www.
e1.
greatlakes.
com/
agproduct/
].
This
assessment
is
focused
on
commodity
uses
and
a
range
of
application
rates
from
1
to
15
lb
ai/
1000ft3
have
been
considered
which
reflect
the
range
of
application
rates
identified
in
the
Phase
3
public
comment
process.
[
Note:
Analyses
were
completed
in
this
assessment
using
application
rates
of
1,
4,
9,
and
15
lb/
1000
cubic
feet.
All
modeling
outputs
are
available
but
the
results
for
the
1
and
4
lb/
1000
cubic
feet
outputs
have
been
summarized
since
they
bracket
uses
for
most
commodities
with
established
food
tolerances
and
the
purpose
of
this
document
is
to
address
the
food
tolerances
associated
with
methyl
bromide
in
order
to
meet
the
August
2006
tolerance
reassessment
schedule
for
FQPA.]

MeBr
application
methods
and
equipment
are
quite
varied
depending
upon
the
setting.
Generally,
the
methods
and
equipment
fall
into
four
basic
categories
that
include:
(
1)
pre­
plant
agricultural
field
fumigations;
(
2)
structural,
industrial,
and
residential
fumigations;
(
3)
post­
harvest
commodity
fumigations;
and
(
4)
other
specialized
fumigations.
This
assessment
focuses
on
the
post­
harvest
commodity
uses
of
methyl
bromide
and
associated
structural/
industrial
uses
that
may
impact
commodities
(
e.
g.,
flour
mills).
Future
assessments
will
address
the
other
use
patterns.
6
H
H
H
Br
MeBr
has
been
identified
as
an
ozone
depleting
chemical
and
as
such
is
scheduled
for
a
phase­
out
by
2005
and
it
is
subject
to
other
restrictions
under
the
Montreal
accords
entered
into
by
the
United
States.
However,
in
certain
situations,
agronomic
needs
can
still
warrant
its
use
under
the
Montreal
accord
because
of
efficacy
reasons
and
the
lack
of
suitable
alternatives.
To
account
for
and
codify
these
uses,
a
process
was
established
which
allows
for
"
Critical
Use
Exemptions
or
CUEs"
which
are
redefined
on
an
annual
basis
in
the
process
established
under
the
accords.
In
2005,
there
are
19
distinct
industry
"
sector"
CUEs
(
pre­
plant
uses
on
cucurbits,
tomatoes,
strawberries,
etc.)
that
allow
the
United
States
to
consume
35
percent
or
so
(
i.
e.,
approximately
19.7
million
pounds)
of
the
1991
baseline
annual
total
amount
used
of
approximately
56.3
million
pounds.
For
2006
the
number
of
industry
"
sectors"
has
been
reduced
to
15
and
the
United
States
will
be
allowed
to
consume
32
percent
of
the
1991
baseline
of
MeBr
(
i.
e.,
approximately
18.0
million
pounds).
However,
for
both
years
the
United
States
is
allowed
to
use
MeBr
for
quarantine
and
pre­
shipment
uses
without
any
controls
on
the
amount
used.

HED
has
closely
coordinated
with
the
California
Department
of
Pesticide
Regulation
(
CDPR)
during
the
development
of
this
assessment
since
CDPR
has
considerable
experience
and
has
also
instituted
requirements
governing
MeBr
use
that
are
more
restrictive
than
those
contained
in
current
Federal
labels
(
http://
www.
cdpr.
ca.
gov/
docs/
dprdocs/
methbrom/
mebrmenu.
htm).
CDPR
has
also
generated
a
majority
of
the
data
considered
in
this
assessment.
In
order
to
allow
MeBr
users
flexibility
and
reduce
exposures,
CDPR
has
opted
to
use
buffer
zones
that
are
determined
based
on
the
factors
included
in
permit
applications.
This
is
done
through
a
series
of
look­
up
tables
that
MeBr
users
reference
for
their
specific
permits.
These
look­
up
tables
are
based
on
broad
combinations
of
application
equipment
and
control
technologies
(
i.
e.,
these
categories
are
commonly
referred
to
as
permit
conditions).
[
Note:
Further
discussion
is
provided
below
about
how
the
modeled
estimations
were
completed.]
CDPR
is
also
considering
how
to
reduce
nonpoint
or
ambient
sources
of
exposure
based
on
the
use
of
township
caps
(
i.
e.,
6
by
6
mile
townships
are
used).

2.1
Structure
and
Nomenclature
Table
1
provides
the
structures
and
relevant
nomenclature
for
MeBr.

Table
1:
Test
Compound
Nomenclature
Properties
Methyl
Bromide
Chemical
Structure
Chemical
Group
Alkyl
Bromide
Common
Name
Methyl
Bromide
Molecular
formula
CH3Br
Molecular
Weight
94.94
CAS
No.
74­
83­
9
PC
Code
053201
7
2.2
Physical
and
Chemical
Properties
A
listing
of
the
physical
and
chemical
properties
of
MeBr
are
provided
in
Table
2.

Table
2:
Physical
and
Chemical
Properties
of
MeBr
Parameter
MeBr
Appearance
colorless,
odorless
gas
at
normal
temperatures
and
pressures
and
a
liquified
gas
under
moderate
pressure
Boiling
Point
3.6
°
C
Vapor
Pressure
1400
mm
Hg
at
20
°
C
Partition
Coefficient
(
log
Pow)
1.19
Solubility
in
Water
1.75
g/
100
mL
at
20
°
C
3.0
Metabolism
3.1
Description
of
Primary
Crop
Metabolism
The
qualitative
nature
of
the
residue
in
plants
is
adequately
understood,
based
on
studies
in
which
the
commodities
maize,
potato,
alfalfa,
peanuts,
almonds,
oatmeal,
apples,
oranges,
and
wheat
were
fumigated
with
radioactive
methyl
bromide
at
a
rate
equivalent
to
~
2x
the
registered
rate.
Residues
consisted
of
methyl
bromide
and
naturally
occurring
compounds
such
as
methylated
amino
acids
and
nucleotides.
The
residue
of
concern
is
methyl
bromide
per
se.

HED
has
determined
that
the
pre­
plant
soil
fumigation
use
is
a
non­
food
use.
Treated
soil
must
be
fumigated
for
a
minimum
of
two
weeks
to
allow
sufficient
dissipation
of
residues;
excessive
residues
of
methyl
bromide
per
se
would
be
phytotoxic.
Minimal
methyl
bromide
residues
are
available
for
uptake
by
the
plant
at
the
end
of
the
soil
aeration
period.
Considering
the
highly
reactive
nature
of
methyl
bromide,
any
residues
taken
up
by
the
plant
would
be
converted
to
natural
constituents
by
the
time
of
plant
harvest.
Therefore,
tolerances
are
not
needed
to
support
the
pre­
plant
fumigation
use
of
methyl
bromide.
However,
tolerances
currently
exist
for
post­
harvest
commodity
fumigation
uses
of
methyl
bromide
(
see
40
CFR
§
180.123).

3.2
Description
of
Livestock
Metabolism
Animal
metabolism
data
are
currently
not
required
for
methyl
bromide.
Potential
feed
items
with
registered
post­
harvest
or
storage
fumigation
uses
include
stored
grain,
soybeans,
and
processed
animal
feeds.
The
maximum
tolerance
for
residues
in
any
of
these
is
10
ppm,
based
on
residues
24
hours
after
the
aeration
period
that
follows
fumigation.
The
transfer
of
detectable
residues
from
feed
items
to
meat,
milk
or
eggs,
is
not
expected,
and
is
a
Category
(
3)
situation
under
40
CFR
§
180.6(
a).

3.3
Description
of
Rat
Metabolism
In
a
metabolism
study
(
non­
guideline,
literature),
rats
received
a
single
gavage
dose
(
preparation
of
test
solution
was
unspecified)
of
24
mg/
kg/
b.
w.
14C­
MeBr.
Over
a
3­
day
period,
the
radioactivity
recovered
was
as
follows:
carcass
(
14­
17%),
expired
carbon
dioxide
(
32%),
urine
(
43%)
and
feces
(
less
than
3%)
8
(
Medinsky
et
al.
1984).
During
a
6­
hour
exposure
of
rats
to
4.75­
9874
mg/
cu.
m
14C­
MeBr
vapor,
approximately
27­
50%
of
the
compound
inhaled
was
absorbed
(
Medinsky
et
al.
1985).

4.0
Hazard
Assessment
and
Characterization
4.1
Hazard
Characterization
4.1.1
Database
Summary
Studies
available
and
acceptable
(
animal,
human,
general
literature)
Data
are
available
for
both
oral
and
inhalation
routes
and
have
been
used
accordingly
in
the
risk
assessments
(
Appendix
A).
The
inhalation
database
includes:
acute
neurotoxicity
study
in
rats,
developmental
toxicity
studies
in
rats
and
rabbits,
subchronic
toxicity
studies
in
rats
and
dogs,
and
chronic
studies
in
mice
and
rats.
Four
studies
conducted
via
the
oral
route
in
rats
and
dogs
were
also
available.
In
addition,
incident
reports
indicate
that
methyl
bromide
exposure
results
in
a
myriad
of
symptoms
ranging
from
headaches
to
death.

Metabolism,
toxicokinetic,
mode
of
action
data
A
guideline
metabolism
study
is
not
available.
Data
in
the
open
literature
indicate
that
methyl
bromide
is
readily
absorbed
with
approximately
27­
50%
of
the
compound
inhaled
absorbed
after
a
six
hour
exposure
(
Medinsky
et
al.
1985).

Sufficiency
of
studies/
data
The
toxicological
database
for
methyl
bromide
is
sufficient
for
risk
assessment
purposes
and
includes
a
Developmental
Neurotoxicity
Study
in
Rats
conducted
via
the
inhalation
route.

4.1.2
Endpoints
Neurotoxicity
is
the
most
prevalent
hazard
concern
for
inhalation
exposure,
with
neurotoxic
effects
seen
throughout
the
data
base
in
all
tested
species.
Both
acute
and
90­
day
inhalation
neurotoxicity
studies
in
rats
showed
evidence
of
neurotoxic
effects
of
methyl
bromide
characterized
by
decreased
activity,
tremors,
ataxia
and
paralysis.
Two
subchronic
studies
demonstrated
dogs
to
be
the
most
sensitive
species
to
the
neurotoxic
effects
of
methyl
bromide.
Neurotoxic
effects
were
also
seen
in
the
chronic/
carcinogenicity
inhalation
study
in
mice
(
ataxia,
limb
paralysis,
degenerative
changes
in
the
cerebellum)
and
in
the
developmental
inhalation
study
in
rabbits
(
lethargy,
right
side
head
tilt,
ataxia).
Developmental
effects
described
as
increased
incidence
of
agenesis
of
the
gallbladder
and
fused
sternebrae
were
also
seen
in
the
developmental
inhalation
study
in
rabbits.
In
addition,
the
multi
generation
reproduction
toxicity
study
in
rats
revealed
that
methyl
bromide
exposure
via
the
inhalation
route
resulted
in
decreases
in
pregnancy
rates
and
body
weights
(
pups
and
adults).

Four
studies
conducted
via
the
oral
route
are
available
in
the
methyl
bromide
database.
Since
methyl
bromide
is
a
gas
under
standard
atmospheric
conditions,
in
dietary
studies
the
test
article
was
administered
micro
encapsulated,
with
the
exception
of
one
study
where
the
feed
was
fumigated.
Effects
noted
after
dietary
exposure
were
primarily
decreases
in
body
weight
gain,
body
weight,
and
food
consumption.
Evidence
of
stomach
lesions
was
seen
in
the
90
day
oral
toxicity
study
in
rats.
9
Several
studies
in
the
database
indicate
that
methyl
bromide
is
a
genotoxic
agent.
However,
no
indications
of
carcinogenesis
were
observed
in
the
rodent
bioassays.
In
contrast,
an
Agricultural
Health
Study
(
AHS)
suggest
a
link
between
prostate
cancer
and
methyl
bromide
use
in
agriculture.

Incident
reports
indicate
that
methyl
bromide
exposure
is
likely
to
cause
symptoms
such
as
headache,
malaise,
weakness,
difficulty
breathing
(
dyspnea),
convulsions,
and
severe
skin
burns.
In
some
instances,
exposure
to
methyl
bromide
has
led
to
deaths
due
to
disregard
of
posted
warnings
on
treated,
tented
structures.

4.1.3
Dose­
response
The
general
public
may
be
exposed
to
fumigants
in
air
because
of
their
volatility
following
application.
Specifically,
fumigants
can
off­
gas
into
ambient
air
and
can
be
transported
off­
site
by
wind
to
nonagricultural
areas.
Based
on
air
monitoring
studies,
exposures
can
be
acute
(
less
than
24
hours),
shortterm
(
1­
30
days),
intermediate­
term
(
1
month­
6
months),
and/
or
long­
term
(>
6
months)
in
duration.
In
addition,
the
U.
S.
population
may
be
exposed
to
methyl
bromide
through
dietary
intake.

4.1.3.1
Inhalation
Exposure
The
critical
effects
of
methyl
bromide
exposure
via
the
inhalation
route
are
agenesis
of
the
gall
bladder
and
fused
sternebrae
observed
in
the
developmental
toxicity
study
in
rabbits,
neurotoxicity
effects,
and
nasal
histopathology
observed
in
the
chronic
toxicity/
carcinogenicity
study
in
rats.
In
evaluating
the
risks
that
a
compound
may
pose
to
human
health
after
exposure
via
the
inhalation
route,
different
methodologies
have
been
historically
used
by
the
U.
S.
EPA
and
CDPR.
The
two
approaches
differ
in
their
use
of
species­
specific
parameters
to
derive
HECs.
Therefore,
the
differences
noted
in
the
risk
assessments
of
each
organization
are
due,
in
part,
to
their
use
of
different
methodologies
and
uncertainty
factors
(
UFs).
HED's
approach
to
estimating
risks
due
to
inhalation
exposure
is
based
on
the
guidance
methodology
developed
by
ORD
for
the
derivation
of
inhalation
reference
concentrations
(
RfCs)
and
human
equivalent
concentrations
(
HECs)
for
use
in
MOE
calculations.
An
example
of
CDPR's
methodology,
and
the
species­
specific
parameters
used
in
this
approach
can
be
found
in
the
CDPR
website
and
their
methyl
bromide
risk
assessment,
Appendix
G
at
the
following
web
address
(
www.
cdpr.
ca.
gov/
docs/
dprdocs/
methbrom/
append_
g.
pdf).
As
OPP
understands
the
importance
to
harmonize,
to
the
extent
possible,
with
other
regulatory
agencies,
this
risk
assessment
will
present
HECs
derived
using
both
methodologies.

For
this
risk
assessment,
endpoint
selection
will
be
based
on
the
endpoints
occurring
at
the
lowest
HECs
(
which
may
or
may
not
be
the
lowest
animal
NOAEL)
derived
using
the
RfC
methodology.
In
this
methodology,
different
HECs
may
be
calculated
for
the
same
experimental
NOAEL
due
to:
1)
the
different
algorithms
used
to
derive
HECs
for
systemic
versus
portal
of
entry
effects;
or
2)
the
time
adjustments
conducted
for
non­
occupational
(
commodity
treatment
facility
bystander
or
agricultural
setting
bystander)
versus
occupational
exposure
scenarios.
The
differences
between
systemic
versus
portal
of
entry
effects,
arise
from
the
use
of
different
calculations
to
estimate
the
inhalation
risk
to
humans
which
are
dependent
on
the
regional
gas
dose
ratio
(
RGDR).
In
the
case
of
systemic
versus
portal
of
entry
effects,
different
RGDRs
are
derived
for
each
type
of
toxicity.
For
agricultural
bystander
exposure
(
i.
e.,
non­
occupational)
versus
worker
exposure
(
i.
e.,
occupational),
the
differences
arise
because
while
it
is
presumed
that
non­
occupational
exposure
may
occur
24
hours/
day,
7
days/
week;
10
occupational
exposure
occurs
only
during
the
course
of
an
average
workweek
(
8
hours/
day
and
5
days/
week).
For
commodity
bystanders
(
i.
e.,
non­
occupational)
exposed
as
a
result
of
commodity
fumigation
in
treatment
facilities,
it
is
presumed
that
exposure
may
occur
during
the
course
of
an
average
workweek
(
8
hours/
day
and
5
days/
week)
while
the
treatment
facility
is
in
operation.

For
further
details
on
the
critical
studies
used
for
endpoint
selection
refer
to
the
Toxicology
Chapter
of
the
reregistration
eligibility
decision
(
RED)
prepared
by
Dr.
Paul
Chin
(
DP
Barcode:
D271581,
Submission:
S586801,
dated
March
18,
2003).
Additional
information
on
the
methodologies
used
in
this
risk
assessment
and
HEC
arrays
is
available
in
Appendix
B.

Acute
Inhalation
Exposure
In
a
developmental
toxicity
study
(
MRID
No.
41580401),
pregnant
New
Zealand
White
rabbits
(
26
animals/
dose)
were
exposed
by
whole
body
inhalation
to
0,
20,
40
or
80
ppm
methyl
bromide
vapor
for
6
hr/
day
on
Days
6­
16
of
gestation.

The
maternal
NOAEL
is
40
ppm
(
HEC
=
10
for
agricultural
bystander
exposure
or
30
ppm
for
occupational
and
commodity
bystander
exposure
)
and
the
LOAEL
is
80
ppm
based
on
decreased
appetite,
lethargy,
right
side
head
tilt,
ataxia
and
lateral
recumbency.

The
developmental
toxicity
NOAEL
is
40
ppm
(
HEC
=
10
for
agricultural
bystander
exposure
or
30
ppm
for
occupational
and
commodity
bystander
exposure
)
and
the
LOAEL
is
80
ppm
based
on
agenesis
of
the
gall
bladder
and
increased
incidence
of
fused
sternebrae
which
was
supported
by
decreased
fetal
body
weight
(
statistically
not
significant).

Dose
and
Endpoint
for
Risk
Assessment:
HEC
of
10
or
30
ppm
for
non­
occupational
and
occupational
risk
assessments,
based
on
agenesis
of
the
gall
bladder
and
increased
incidence
of
fused
sternebrae.
It
is
presumed
that
developmental
effects
such
as
agenesis
of
the
gall
bladder
and
fused
sternebrae
may
be
the
outcome
of
an
acute
exposure
thus
this
study
is
considered
appropriate
for
this
risk
assessment.
Though
an
acute
neurotoxicity
study
in
rats
was
available
for
consideration,
the
developmental
toxicity
study
in
rabbits
was
selected
since
it
yields
the
lowest
HEC
(
most
health­
protective).
A
30X
UF
defines
HED's
level
of
concern
(
3X
interspecies
extrapolation
and
10x
intraspecies
variation)
in
accordance
with
guidance
provided
in
the
RfC
methodology
(
see
section
4.2
below).

Short
and
Intermediate
Inhalation
Exposure
Short
and
intermediate
inhalation
risk
assessments
were
based
on
two
subchronic
inhalation
toxicity
studies
in
dog.
In
a
subchronic
(
5­
to
7­
week)
inhalation
toxicity
study
(
MRID
43386802),
methyl
bromide
(
tech.,
100%
a.
i.)
was
administered
7
hours/
day,
5
days/
week
to
4
beagle
dogs/
sex/
dose
by
whole
body
exposure
at
target
concentrations
of
0,
5,
10/
150,
25,
50
or
100
ppm
(
actual
mean
concentrations
0,
5.3,
11.0/
158.0,
26.0,
53.1
or
102.7
ppm;
equivalent
to
0,
0.021,
0.043/
0.614,
0.101,
0.206
or
0.399
mg/
L).
The
systemic
toxicity
NOAEL
for
5
and
7
weeks
is
26
ppm
(
HEC
=
5.41
ppm
for
agricultural
bystanders
or
22.75
ppm
for
occupational
and
commodity
bystander
exposure).
The
LOAEL
is
53.1
ppm
based
on
decreased
activity.
2
Due
to
the
limited
severity
of
the
effect,
HED
considered
that
a
3X
UF
would
be
sufficient
to
extrapolate
from
the
LOAEL
to
the
NOAEL.

11
In
a
six­
week
nonguideline
inhalation
toxicity
study
(
MRID
45722801),
four
groups
of
beagle
dogs
consisting
of
4
males
and
4
females/
group
were
administered
methyl
bromide
(
Lot
No:
1010PK15A;
purity:
100%
a.
i.)
by
whole
body
exposure
at
concentrations
of
0,
5.3,
10,
and
20
ppm
(
equivalent
to
0,
1.8,
3.4
and
6.9
mg/
kg/
day).
The
exposures
were
for
seven
hours/
day,
five
days/
week
for
six
weeks
(
total
of
30
exposures).

The
NOAEL
is
5.3
ppm
(
HEC
=
1.0
for
agricultural
bystander
exposure
or
4.4
ppm
occupational
and
commodity
bystander
exposure),
and
the
LOAEL
for
methyl
bromide
is
10
ppm
based
on
the
absence
of
proprioceptive
placing
and
the
increased
incidence
of
feces­
findings
(
soft,
mucoid
feces,
and/
or
diarrhea).

Dose
and
Endpoint
for
Risk
Assessment:
HEC
=
1.0
for
agricultural
bystander
exposure
or
4.4
ppm
for
occupational
and
commodity
bystander
exposure
based
on
the
absence
of
proprioceptive
placing
and
the
increased
incidence
of
feces­
findings
(
soft,
mucoid
feces,
and/
or
diarrhea).
This
study
is
of
the
appropriate
duration
for
these
risk
assessments
and
yield
the
lowest
HECs
of
the
studies
of
this
duration.
An
UF
of
30X
defines
HED's
level
of
concern
in
accordance
with
guidance
provided
in
the
RfC
methodology
(
see
section
4.2
below).

Chronic
Inhalation
Exposure
In
a
chronic
toxicity/
carcinogenicity
study
(
MRIDs
41213301,
42418301,
44359101),
50
Wistar
(
Cpb:
Wu)
rats/
sex/
dose
were
exposed
to
methyl
bromide
(>
98.8%
a.
i.)
by
whole
body
exposure
at
concentrations
of
0,
3,
30
or
90
ppm
(
0,
0.0117,
0.117
or
0.335
mg/
L)
for
127
weeks
(
males)
or
129
weeks
(
females).

No
NOAEL
was
identified
for
local
respiratory
effects.
The
LOAEL
for
local
respiratory
irritation
is
3
ppm
(
HEC
=
0.13
ppm
for
agricultural
bystander
exposure
or
0.55
ppm
for
occupational
and
commodity
bystander
exposures)
based
on
increased
incidence
of
basal
cell
hyperplasia
of
the
nasal
cavity
in
both
sexes.

The
NOAEL
for
systemic
toxicity
is
30
ppm
(
HEC
=
5.36
ppm
for
agricultural
bystanders
or
22.5
ppm
for
occupational
and
commodity
bystander
exposures).
The
LOAEL
is
90
ppm
based
on
increased
mortality,
decreased
body
weight
and
relative
brain
weight,
hemothorax,
increased
incidence
of
thrombus,
cartilaginous
metaplasia,
myocardial
degeneration
and
irritation
of
the
esophagus
and
forestomach.

Dose
and
Endpoint
for
Risk
Assessment:
HEC
of
0.13
ppm
for
agricultural
bystander
exposure
or
0.55
ppm
for
occupational
and
commodity
bystander
exposures
based
on
increased
incidence
of
basal
cell
hyperplasia
of
the
nasal
cavity
in
both
sexes.
This
study
is
of
the
appropriate
duration
and
yields
the
lowest
HECs
for
this
risk
assessment.
Since
a
NOAEL
was
not
identified
for
the
effect
of
concern
(
nasal
histopathology)
a
3X
UF
for
LOAEL
to
NOAEL
extrapolation
is
recommended.
2
Thus
an
UF
of
100X
(
3X
interspecies
extrapolation,
10X
intraspecies
variation,
and
3X
LOAEL
to
NOAEL
extrapolation)
12
defines
HEDs
level
of
concern
in
accordance
with
guidance
provided
in
the
RfC
methodology
(
see
section
4.2
below).
4.1.3.2
Dietary
Exposure
Acute
Dietary
Exposure
for
Females
13­
50
Years
of
Age
For
acute
dietary
exposure
for
females
of
child
bearing
age,
refer
to
section
4.1.4.1
Inhalation
Exposure,
Acute
Inhalation
Exposure.

Dose
and
Endpoint
for
Risk
Assessment:
NOAEL
of
40
ppm
(
14
mg/
kg/
day)
based
on
agenesis
of
the
gallbladder
and
fused
sternebrae.
For
acute
reference
dose
derivation,
a
100X
uncertainty
factor
is
applied
(
10x
interspecies
extrapolation
and
10x
intraspecies
variation
see
section
4.2
below).
HED
considers
this
to
be
a
health
protective
dose
and
endpoint
for
dietary
risk
assessment
purposes
since
an
inhalation
study
was
used,
which
is
likely
to
overestimate
the
internal
dose
that
would
result
from
an
oral
exposure
since
chemicals
will
enter
the
circulation
before
many
of
the
detoxification
processes
associated
with
oral
exposure
(
e.
g.
first
pass
effect)
occur.
Moreover,
chemicals
in
the
respiratory
tract
enter
the
blood
stream
more
readily
than
chemicals
in
the
gastrointestinal
tract
(
GI)
since
only
­

2:
M
separate
the
chemical
in
the
alveolar
space
of
the
lung
and
the
blood
stream
while
several
cellular
layers
separate
the
chemicals
in
the
lumen
of
the
GI
tract
from
the
blood
stream..

Acute
Dietary
Exposure
for
General
Population
In
an
acute
neurotoxicity
study
(
MRID
No.
42793601),
CD
rats
(
15
rats/
sex/
dose)
were
exposed
by
whole
body
inhalation
to
0,
30,
100
or
350
ppm
methyl
bromide
vapor
for
6
hours
(
equivalent
to
males:
0,
27,
90
or
314
mg/
kg/
day
and
females:
0,
30,
101,
or
354
mg/
kg/
day).
The
NOAEL
is
100
ppm
and
the
LOAEL
is
350
ppm
decreased
activity,
increase
in
number
of
animals
with
drooping/
half­
closed
eyelids
and
alertness
as
measured
in
a
FOB
examination,
decreased
rears,
decreased
motor
activity,
increased
piloerection
and
decreased
body
temperature
in
males
and
females
after
dosing.

Dose
and
Endpoint
for
Risk
Assessment:
NOAEL
is
100
ppm
(
90
mg/
kg/
day)
based
on
decreased
activity,
increase
in
number
of
animals
with
drooping/
half­
closed
eyelids
and
alertness
as
measured
in
a
FOB
examination,
decreased
rears,
decreased
motor
activity,
increased
piloerection
and
decreased
body
temperature.
For
acute
reference
dose
derivation,
a
100X
uncertainty
factor
is
applied(
10x
interspecies
extrapolation
and
10x
intraspecies
variation;
see
uncertainty
factors
discussion
below).
Once
again,
HED
considers
this
to
be
a
health
protective
dose
and
endpoint
for
dietary
risk
assessment
purposes
since
an
inhalation
study
was
used,
which
is
likely
to
overestimate
the
internal
dose
that
would
result
from
an
oral
exposure
since
chemicals
will
enter
the
circulation
before
many
of
the
detoxification
processes
associated
with
oral
exposure
(
e.
g.
first
pass
effect)
occur.
Moreover,
chemicals
in
the
respiratory
tract
enter
the
blood
stream
more
readily
than
chemicals
in
the
gastrointestinal
(
GI)
tract
since
only
­

2:
M
separate
the
chemical
in
the
alveolar
space
of
the
lung
and
the
blood
stream
while
several
cellular
layers
separate
the
chemicals
in
the
lumen
of
the
GI
tract
from
the
blood
stream.

Chronic
Dietary
Exposure
In
a
combined
chronic
toxicity/
carcinogenicity
study
(
MRID
44462501),
microencapsulated
methyl
bromide
was
administered
to
4
groups
of
male
and
female
Crl:
CD
®
(
SD)
BR
rats
for
a
period
of
12
or
24
months
(
interim
and
main
study,
respectively)
in
the
diet
at
concentrations
of
0
(
diet
control),
0
(
placebo
control),
0.5,
2.5,
50,
or
250
ppm.
These
concentrations
were
equivalent
to
0,
0.02,
0.11,
2.20
and
11.10
mg/
kg/
day
in
males
and
0,
0.03,
0.15,
2.92
and
15.12
mg/
kg/
day
in
females.
The
NOAEL
is
13
50
ppm
(
2.20
mg/
kg/
day
for
males
and
2.92
mg/
kg/
day
for
females).
The
LOAEL
is
250
ppm
(
11.10
mg/
kg/
day
for
males
and
15.12mg/
kg/
day
for
females),
based
on
decreased
body
weight,
body
weight
gain
and
food
consumption
in
males
and
females
during
the
first
18
months
of
the
study.

Dose
and
Endpoint
for
Risk
Assessment:
The
NOAEL
is
50
ppm
(
2.20
mg/
kg/
day
for
males
and
2.92
mg/
kg/
day
for
females)
based
on
decreased
body
weight,
body
weight
gain
and
food
consumption.
For
chronic
reference
dose
derivation,
a
100X
uncertainty
factor
is
applied
(
10x
interspecies
extrapolation,
10x
intraspecies
variation;
see
section
4.2
below).

4.1.3.3
Dermal
Exposure
Dermal
exposure
to
methyl
bromide
of
any
significance
is
not
expected
based
on
the
delivery
systems
used
(
e.
g.,
soil
injection
or
drip
irrigation),
packaging
(
i.
e.,
pressurized
cylinders),
and
emission
reduction
technologies
(
e.
g.,
tarping).
The
high
vapor
pressure
of
methyl
bromide
also
makes
significant
dermal
exposure
unlikely
and
quantifying
any
potential
low
level
exposures
very
difficult.
Therefore,
a
quantitative
dermal
exposure
assessment
has
not
been
completed.
Since
HED
does
not
have
adequate
data
to
quantify
dermal
risk,
PPE
for
dermal
protection
should
be
based
on
the
acute
toxicity
of
the
enduse
product
as
described
in
the
Worker
Protection
Standard
and
mitigation
measures
for
dermal
exposure
described
in
PR
Notice
93­
7.

4.1.3.4
Classification
of
Carcinogenic
Potential
At
this
time,
methyl
bromide
is
classified
as
a
not
likely
human
carcinogen;
consequently,
no
q
1
*
or
cancer
risk
quantification
is
required.
However,
initial
results
of
an
Agricultural
Health
Study
(
AHS)
suggest
a
link
between
prostate
cancer
and
,
ethyl
bromide
use
in
agriculture.
Study
information
is
being
updated
and
review
of
family
history
and
possible
confounding
factors
are
being
considered.
EPA
will
consider
revising
the
cancer
classification
when
these
results
become
available.

4.1.4
Endocrine
Disruption
EPA
is
required
under
the
FFDCA,
as
amended
by
FQPA,
to
develop
a
screening
program
to
determine
whether
certain
substances
(
including
all
pesticide
active
and
other
ingredients)
"
may
have
an
effect
in
humans
that
is
similar
to
an
effect
produced
by
a
naturally
occurring
estrogen,
or
other
such
endocrine
effects
as
the
Administrator
may
designate."
Following
the
recommendations
of
its
Endocrine
Disruptor
Screening
and
Testing
Advisory
Committee
(
EDSTAC),
EPA
determined
that
there
was
scientific
bases
for
including,
as
part
of
the
program,
the
androgen
and
thyroid
hormone
systems,
in
addition
to
the
estrogen
hormone
system.
EPA
also
adopted
EDSTAC's
recommendation
that
the
Program
include
evaluations
of
potential
effects
in
wildlife.
For
pesticide
chemicals,
EPA
will
use
FIFRA
and,
to
the
extent
that
effects
in
wildlife
may
help
determine
whether
a
substance
may
have
an
effect
in
humans,
FFDCA
authority
to
require
the
wildlife
evaluations.
As
the
science
develops
and
resources
allow,
screening
of
additional
hormone
systems
may
be
added
to
the
Endocrine
Disruptor
Screening
Program
(
EDSP).
When
the
appropriate
screening
and/
or
testing
protocols
being
considered
under
the
Agency's
EDSP
have
been
developed,
methyl
bromide
may
be
subjected
to
additional
screening
and/
or
testing
to
better
characterize
effects
related
to
endocrine
disruption.
14
4.2
Uncertainty
Factors
HED
determined
that
the
special
FQPA
factor
could
be
reduced
to
1x
based
on
the
present
toxicological
database
and
adequacy
of
uncertainty
factors
assigned
to
chosen
endpoints.
Clear
NOAELs
were
identified
for
all
studies
used
for
endpoint
selection,
and
their
dose
response
was
well
defined.
Consequently,
selected
points
of
departure
(
PODs)
will
not
underestimate
the
risk.
A
Developmental
Neurotoxicity
Study
in
rats
has
been
received
and
reviewed
by
the
Agency.
Therefore,
the
database
uncertainty
factor
(
UFDB)
of
10x
previously
retained
for
lack
of
the
DNT
has
been
removed
for
all
risk
assessments
in
accordance
to
current
HED
policy.

When
conducting
inhalation
risk
assessments,
the
magnitude
of
the
UFs
applied
is
dependent
on
the
methodology
used
to
estimate
risk.
This
risk
assessment
is
based
on
the
RfC
methodology
developed
by
ORD
for
the
derivation
of
inhalation
RfCs
and
HECs
for
use
in
MOE
calculations.
Since
the
RfC
methodology
takes
into
consideration
many
pharmacokinetic
(
PK)
differences
but
not
pharmacodynamic
(
PD)
differences,
the
UF
for
interspecies
extrapolation
may
be
reduced
to
3x
(
to
account
for
the
PD
differences)
while
the
UF
for
intraspecies
variation
is
retained
at
10x.
Thus,
the
UF
when
using
the
RfC
methodology
is
customarily
30x.

Uncertainty
factors
may
also
be
applied
to
account
for
LOAEL
to
NOAEL
extrapolations.
In
the
case
of
methyl
bromide,
no
NOAEL
was
identified
for
the
portal
of
entry
effects
observed
in
the
chronic/
carcinogenicity
inhalation
study
in
rats
that
was
used
for
the
long­
term
inhalation
risk
assessment.
Since
the
effects
noted
at
this
dose
level
were
not
severe,
an
uncertainty
factor
of
3x
was
applied
for
the
LOAEL
to
NOAEL
extrapolation.

4.3
Summary
of
Toxicological
Endpoint
Selection
Table
3:
Summary
of
Toxicological
Dose
and
Endpoints
for
Use
in
MeBr
Oral
Human
Health
Risk
Assessments
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
Special
FQPA
SF*
and
Level
of
Concern
for
Risk
Assessment
Study
and
Toxicological
Effects
Acute
Dietary
(
Females
13­
50
years
of
age)
Dev.
NOAEL
=
14
mg/
kg/
day
UF
=
100
Acute
RfD
=
0.14
mg/
kg/
day
FQPA
SF
=
1X
aPAD
=
acute
RfD
FQPA
SF
=
0.14
mg/
kg/
day
Developmental
Toxicity
­
Rabbit
(
Inhalation)
LOAEL
=
28
mg/
kg/
day
based
on
agenesis
of
the
gall
bladder
and
increased
incidence
of
fused
sternebrae.

Acute
Dietary
(
General
population
including
infants
and
children)
NOAEL
=
90
mg/
kg/
day
UF
=
100
Acute
RfD
=
0.9
mg/
kg/
day
FQPA
SF
=
1X
aPAD
=
acute
RfD
FQPA
SF
=
0.9
mg/
kg/
day
Acute
neurotoxicity
study
­­
rat
(
Inhalation)
LOAEL
=
314
mg/
kg/
day
based
on
decreased
activity,
increase
in
number
of
animals
with
drooping/
half­
closed
eyelids
and
alertness
as
measured
in
the
FOB,
decreased
rears,
decreased
motor
activity,
increased
piloerection
and
decreased
body
temperature
Table
3:
Summary
of
Toxicological
Dose
and
Endpoints
for
Use
in
MeBr
Oral
Human
Health
Risk
Assessments
Exposure
Scenario
Dose
Used
in
Risk
Assessment,
UF
Special
FQPA
SF*
and
Level
of
Concern
for
Risk
Assessment
Study
and
Toxicological
Effects
15
Chronic
Dietary
(
All
populations)
NOAEL=
2.2
mg/
kg/
day
UF
=
100
Chronic
RfD
=
0.02
mg/
kg/
day
FQPA
SF
=
1X
cPAD
=
chronic
RfD
FQPA
SF
=
0.02
mg/
kg/
day
Chronic/
carcinogenicity
study
­­
rats
(
Microencapsulated
MeBr)
LOAEL
=
11.1
mg/
kg/
day
based
on
decreased
body
weight,
body
weight
gain
and
food
consumption
Cancer
Classification:
Not
likely
to
be
carcinogenic
to
humans
Table
4:
Summary
of
Toxicological
Dose
and
Endpoints
for
Use
in
MeBr
Human
Health
Inhalation
Risk
Assessment
Risk
Assessment*
Study
NOAEL/
LOAEL
Endpoints
HED
HECs
CPDR
HECs
¶

Acute
Agricultural
Bystander
Developmental
Study
in
Rabbits
NOAEL
=
40
ppm
LOAEL
=
80
ppm
Maternal:
Right
head
tilt,
ataxia.
Developmental
effects:
agenesis
of
gallbladder,
fused
sternebrae
10
ppm
UF
=
30
21
ppm
UF
=
100
(
child
&
adult)

Occupational
&
Commodity
Bystander
Developmental
Study
in
Rabbits
NOAEL
=
40
ppm
LOAEL
=
80
ppm
Maternal:
Right
head
tilt,
ataxia.
Developmental
effects:
agenesis
of
gallbladder,
fused
sternebrae
30
ppm
UF
=
30
Short­
and
Intermediat
e­
Term
Inhalation
(
1
day
to
6
months)
Agricultural
Bystander
Subchronic
(
5­
to
7­
week)
inhalation
toxicity
study
­
dogs
NOAEL
=
5
ppm
LOAEL
=
10ppm
Decreased
responsiveness
in
females,
fecal
effects
and
eye
irriation
1.0
ppm
UF
=
30
0.88
ppm
UF
=
100
(
child
Occupational
&
Commodity
Bystander
Subchronic
(
5­
to
7­
week)
inhalation
toxicity
study
­
dogs
NOAEL
=
5
ppm
LOAEL
=
10ppm
Decreased
responsiveness
in
females,
fecal
effects
and
eye
irriation
4.4
ppm
UF
=
30
1.56
ppm
UF
=
100
(
adult)
Table
4:
Summary
of
Toxicological
Dose
and
Endpoints
for
Use
in
MeBr
Human
Health
Inhalation
Risk
Assessment
Risk
Assessment*
Study
NOAEL/
LOAEL
Endpoints
HED
HECs
CPDR
HECs
¶

16
Long­
Term
Inhalation
(>
6
months)
Agricultural
Bystander
Chronic/
Carcinogenicity
­
rats
No
NOAEL
identified.
LOAEL
=
3
ppm
Nasal
lesions
0.13
ppm
UF
=
100
0.1
ppm
UF
=
100
(
child)

Occupational
&
Commodity
Bystander
Chronic/
Carcinogenicity
­
rats
No
NOAEL
identified.
LOAEL
=
3
ppm
Nasal
lesions
0.55
ppm
UF
=
100
0.2
ppm
UF
=
100
(
adult)

Cancer
Classification:
Not
likely
to
be
carcinogenic
to
humans
*
Agricultural
bystander
HECs
have
also
been
applied
to
24
hour
Time­
Weighted­
Average
exposure
concentrations
measured
from
ambient
air.
All
bystander
assessments
are
non­
occupational,
by
definition.
Commodity
bystanders
are
all
based
on
8
hour
durations.
¶
Though
CDPR
and
USEPA
based
their
risk
assessments
on
the
same
critical
studies
and
endpoints,
different
algorithms
were
used
by
each
organization
to
calculate
HECs.
For
further
details,
please
refer
to
Appendix
B
of
this
document.

5.0
Public
Health
Data
An
analysis
of
incidents
related
to
MeBr
use
that
considered
data
from
the
OPP
Incident
Data
System
(
IDS),
Poison
Control
Centers,
CDPR,
and
National
Pesticide
Information
Center
was
completed.
MeBr
has
a
number
of
different
types
of
hazards
associated
with
both
agricultural
and
structural
applications.
Often
formulated
with
chloropicrin
as
a
warning
agent,
a
sizeable
number
of
cases
result
from
the
irritating
properties
of
the
chloropicrin
which
can
cause
skin,
eye,
and
respiratory
irritation
which
may
result
in
tearing
and
cough.
MeBr
is
more
likely
to
be
involved
when
symptoms
include
headache,
malaise,
weakness,
difficulty
breathing
(
dyspnea),
convulsions,
and
severe
skin
burns.
Either
chloropicrin
or
MeBr
can
be
associated
with
vomiting
and
diarrhea,
though
MeBr
would
appear
to
be
the
more
likely
culprit
if
no
odor
is
involved.
MeBr
formulated
with
or
without
chloropicrin
has
been
responsible
for
a
number
of
incidents
involving
large
clusters
of
people.
The
need
for
Hazmat
teams,
decontamination,
and
medical
care
make
these
cases
significant,
even
though
symptoms
are
often
minor.
Incidents
have
been
associated
with
faulty
containers
and
application
equipment.
MeBr
has
also
been
responsible
for
a
significant
number
of
deaths,
most
involving
individuals
not
directly
involved
in
the
application.
Fifteen
deaths
in
California
(
1982­
99)
and
4
deaths
reported
in
the
Incident
Data
System
(
all
in
Florida)
involved
burglars,
residents,
and
other
persons
ignoring
posted
warnings
and
breaking
through
the
tented
covering.
There
were
two
deaths,
one
in
a
California
apartment
and
one
in
an
Iowa
restaurant,
where
death
occurred
after
the
structure
was
deemed
safe
to
reenter.
Seven
deaths
were
reported
when
persons
in
adjacent
structures
were
exposed
to
MeBr
without
any
warning.
In
addition
to
these
deaths,
other
cases
of
severe
poisoning
have
been
associated
with
exposure
in
structures
adjacent
to
those
being
fumigated.
In
California,
nearly
70
percent
of
the
poisonings
were
occupational
and
half
of
those
occurred
in
agricultural
settings.
Of
the
278
cases
attributed
to
MeBr
from
1982
through
1999,
MeBr
was
definitely
considered
the
causal
agent
in
42
percent
of
cases,
probable
in
32
percent,
and
possible
in
26
percent.
Factors
identified
in
the
more
serious
cases
included
lack
of
training
and
proper
protective
equipment,
fumigation
of
tree
holes,
inadvertent
exposure
to
leaking
structures
or
structures
with
unexpected
conduits
or
openings,
and
working
in
soil
or
other
areas
where
residues
remained.

Severe
chronic
effects,
sometimes
resulting
in
lifetime
disability,
have
been
reported
from
MeBr
poisoning.
For
example,
four
such
cases
included
worker
with
slow
cognition,
depression,
swings
in
mood,
weakness
and
persistent
muscle
pains;
a
case
that
was
hospitalized
for
16
months
after
exposure
17
with
paranoia
and
depression;
and
a
case
off
work
for
eight
months
due
to
fatigue
and
inability
to
carry
out
normal
work
activities.
Nearly
all
of
the
chronic
effects
described
above
resulted
from
heavy
exposure
and
severe
acute
poisoning.
Other
studies
of
more
moderately
exposed
workers
did
not
reveal
such
effects.
For
example,
a
study
by
Calvert
et
al
considered
123
structural
applicators
in
Florida
and
concluded
"
few
health
effects
were
associated
with
MeBr
exposure."
(
Calvert
GM,
Mueller
CA,
Fajen
JM,
Chrislip
DW,
Russo
J,
Briggle
T,
Fleming
LE,
Suruda
AJ,
Steenland
K.
(
1998)
Health
effects
associated
with
sulfuryl
fluoride
and
MeBr
exposure
among
structural
fumigation
workers.
Am
J
Public
Health
88:
1774­
1780.)

6.0
Non­
Occupational
Exposure
Assessment
and
Characterization
This
section
describes
the
potential
non­
occupational
exposure
scenarios
associated
with
the
use
of
methyl
bromide.
These
include
residential
bystander
exposure
from
two
key
sources
including:
known
sources
from
an
application
site
(
e.
g.,
a
source
such
as
from
a
ventilation
stack
on
a
treated
commodity
chamber
during
aeration)
and
ambient
air
levels
that
result
from
many
applications
within
a
region
where
the
sources
are
not
quantified.
There
are
no
residential
uses
of
methyl
bromide
by
homeowners
so
this
aspect
of
the
risk
assessment
focuses
on
those
types
of
exposures
that
may
occur
from
commercial
uses
of
methyl
bromide
that
can
lead
to
exposures
in
residential
environments.
HED
also
considered
potential
dietary
exposures
from
food
and
drinking
water.
Section
6.1:
Residential
Bystander
Exposure
And
Risk
Estimates
describes
how
exposure
and
risk
estimates
were
calculated
for
the
general
population
who
may
be
exposed
living
in
proximity
to
individual
application
sites
or
within
regions
where
Methyl
bromide
use
routinely
occurs.
Section
6.2:
Bystander
Risk
Characterization
describes
the
factors
that
should
be
considered
when
interpreting
the
results
of
this
risk
assessment.
Section
6.3:
Residue
Profile
describes
the
residue
data
that
were
considered
for
the
dietary
risk
assessment.
Section
6.4:
Acute
and
Chronic
Food
Dietary
Exposure
And
Risk
describes
the
dietary
assessment
completed
for
Methyl
bromide.
Section
6.5:
Water
Exposure/
Risk
Pathway
describes
issues
related
to
the
potential
for
drinking
water
exposure.

6.1
Residential
Bystander
Exposure
and
Risk
Estimates
Methyl
bromide
is
a
widely
used
fumigant
product
where
the
predominant
usage,
in
terms
of
pounds
domestically
applied,
is
accounted
for
by
pre­
plant
soil
fumigation
in
cropland
intended
for
the
cultivation
of
crops
such
as
strawberries
and
tomatoes.
Previously,
the
Agency
completed
a
preliminary
assessment
that
addresses
all
use
patterns
associated
with
methyl
bromide
(
see
www.
Regulations.
gov
and
methyl
bromide
docket
EPA­
HQ­
OPP­
2005­
0123).
However,
the
scope
of
the
preliminary
assessment
has
been
modified
by
separating
out
commodity
uses
from
other
use
patterns
which
will
be
assessed
at
a
later
time.
As
such,
this
document
addresses
only
those
exposure
patterns
which
have
an
associated
commodity
use
as
defined
by
established
food
tolerances
in
40CFR.
Other
similar
uses
which
do
not
have
a
food
tolerance
are
included
as
well
as
appropriate
(
e.
g.,
timber
and
forest
product
exports).

Residential
bystander
exposure
from
commodity
treatments
may
occur
because
of
emissions
from
chambers,
buildings
and
other
structures,
or
stored
commodities
themselves.
These
emissions
can
travel
to
non­
target
areas
which
could
lead
to
negative
impacts
on
human
health
and
will
be
referred
to
simply
as
bystander
risks
in
this
assessment.
Bystander
exposures
can
occur
as
a
result
of
being
in
contact
with
residues
that
were
emitted
from
a
known
source
and
also
from
non­
quantified
source(
s)
within
a
localized
region.
For
clarity,
a
known
source
in
this
assessment
is
intended
to
represent
area
sources
from
a
single
18
application
(
e.
g.,
a
large
warehouse
or
mill
the
is
undergoing
treatment)
or
point
sources
from
a
single
application
(
e.
g.,
stack
used
to
dissipate
residues
from
a
treated
commodity
chamber).
[
Note:
Methyl
bromide
use
practices
can
dictate
that
multiple,
sequential
applications
such
as
in
adjacent
warehouses
during
high
import
season
activity
for
some
commodities
(
e.
g.,
grapes)
could
lead
to
multiple
known
sources.
At
this
time,
the
Agency
will
further
evaluate
such
situations
during
risk
management
in
order
to
tailor
results
to
particular
risk
management
needs.]

When
considering
the
potential
risks
of
bystanders
for
known
sources
from
single
applications
(
e.
g.,
a
commodity
chamber)
it
is
important
to
consider
the
iterative
process
that
reflects
the
evolution
of
HED's
methodologies
for
calculating
the
potential
risks
associated
with
fumigant
use.
There
are
a
number
of
volatility
studies
which
quantified
methyl
bromide
emissions
from
treated
facilities.
However,
these
data
were
limited
in
their
utility
because
they
provide
results
only
for
the
specific
conditions
under
which
the
experiments
were
conducted.
Therefore,
to
provide
flexibility,
HED
also
used
ISCST3
or
the
Industrial
Source
Complex:
Short­
Term
Model
(
Version
3)
to
develop
risk
estimates
for
bystanders
(
http://
www.
epa.
gov/
scram001/).
[
See
http://
www.
epa.
gov/
scram001/
guidance/
guide/
appw_
03.
pdf
for
additional
information
concerning
the
development
and
validation
of
ISCST3.]
HED's
methodology
in
using
ISCST3
and
the
results
achieved
are
considered
deterministic
because
fixed
meteorological
conditions
were
used
rather
than
actual
meteorological
data.
As
such,
in
addition
to
HED's
methodologies
based
on
ISCST3
for
assessing
risks
for
pre­
plant
soil
fumigants,
three
other
models
that
incorporate
ISCST3
variability
in
weather
and
emissions
(
PERFUM,
FEMS,
SOFEA)
were
reviewed
by
the
FIFRA
SAP
in
August
and
September
of
2004
(
http://
www.
epa.
gov/
scipoly/
sap/
2004/
index.
htm).
The
SAP
concluded
that
each
of
the
three
models
could
provide
scientifically
defensible
results
for
risks
associated
with
soil
fumigation
practices
and
also
suggested
modifications
and
additional
data
that
could
further
refine
risk
estimates.
Since
then,
PERFUM
has
been
updated
in
order
to
address
additional
source
types
instead
of
just
agricultural
fields
(
http://
www.
sciences.
com/
perfum/
index.
html).
The
updated
version
of
PERFUM
is
capable
of
estimating
results
for
agricultural
fields
of
different
sizes
and
shapes.
Additionally,
PERFUM
can
model
releases
from
structures
(
e.
g.,
greenhouses
and
chambers
of
different
sizes
and
shapes),
appropriate
for
evaluating
potential
releases
from
commodity
treatments.
The
other
two
models
which
were
evaluated
by
the
SAP
in
2004
(
i.
e.,
FEMS
&
SOFEA)
at
this
point
do
not
have
the
capability
of
addressing
use
patterns
of
this
nature.

HED
also
believes
PERFUM,
instead
of
the
techniques
employed
using
ISCST3,
provide
more
appropriate
information
for
risk
managers
for
evaluating
the
risks
associated
with
commodity
fumigation.
PERFUM
has
the
capability
to
provide
distributional
outputs
which
better
characterizes
the
anticipated
range
of
exposures
that
can
be
expected
to
be
associated
with
the
commodity
use
pattern.
As
such,
HED
recommends
results
derived
from
PERFUM
to
be
the
basis
for
risk
management
decisions
rather
than
those
generated
with
ISCST3.
HED
would
also
evaluate
submissions
based
on
the
other
appropriate
models
if
detailed
training
and
documentation
accompanied
any
such
submission.

For
exposures
from
ambient
air
(
i.
e.,
attributable
to
many
non­
quantified
application(
s)
in
a
region),
air
concentrations
of
MeBr
are
estimated
from
monitoring
data
collected
to
represent
such
conditions
within
regions
of
use
and
also
from
urban
levels.
In
this
analysis,
two
types
of
data
have
been
used:
data
targeted
towards
areas
and
seasons
of
high
MeBr
use
(
i.
e.,
referred
to
as
California
Air
Resources
Board
19
data
or
CARB
available
at
http://
www.
cdpr.
ca.
gov/
docs/
dprdocs/
methbrom/
mebrmenu.
htm
described
as
ambient
air
monitoring
data),
and
data
representing
background
levels
in
non­
agricultural,
urban
environments
(
i.
e.,
referred
to
as
Toxic
Air
Contaminant
data
or
TAC
available
at
http://
www.
arb.
ca.
gov/
adam/
toxics/
toxics.
html
).

Exposures
from
single
known
sources
(
e.
g.,
stacks
from
commodity
chamber)
for
bystanders
are
described
below
in
Section
6.1.1:
Bystander
Exposures
And
Risks
From
Known
Sources
while
ambient
air
exposures
are
described
below
in
Section
6.1.2:
Ambient
Bystander
Exposure
From
Multiple
Regional
Sources.

6.1.1
Bystander
Exposures
And
Risks
From
Known
Sources
As
noted,
residential
bystander
exposure
may
occur
because
of
emissions
due
to
single
applications
from
known
sources
such
as
chambers,
buildings
and
other
structures,
or
stored
commodities.
The
techniques
used
to
assess
the
exposures
and
risks
vary
and
are
described
below
in
Section
6.1.1.1:
Methods
Used
To
Calculate
Bystander
Exposures
And
Risks
From
Known
Sources.
The
results
calculated
for
all
scenarios
of
interest
based
on
the
most
appropriate
method
for
that
scenario
are
presented
in
Section
6.1.1.2:
Bystander
Exposures
And
Risks
From
Known
Sources.

6.1.1.1
Methods
Used
To
Calculate
Bystander
Exposures
And
Risks
From
Known
Sources
As
indicated
above,
the
Agency's
calculation
of
bystander
exposures
and
risks
from
known
sources
has
been
an
iterative
process.
The
methods
used
to
estimate
these
types
of
exposures
are
described
below
along
with
a
discussion
of
the
results
and
how
they
can
be
used
to
represent
the
exposures
and
risks
that
could
be
expected
from
actual
methyl
bromide
use.

HED
considered
a
large
database
of
information
in
its
development
of
the
commodity
assessment
for
methyl
bromide.
The
citations
are
included
in
a
bibliography
attached
as
Appendix
C
(
refer
to
studies
with
COM
prefix).
This
bibliography
lists
the
numbers
of
studies
and
other
documents
(
e.
g.,
guidance)
that
have
been
considered.
HED
screened
these
studies
to
determine
their
usefulness
in
assessing
human
health
risks.
Data
from
those
determined
to
be
applicable
were
extracted
and
used
as
appropriate
for
the
analysis
described
below.

Three
methods
have
been
used
for
assessing
the
potential
risks
associated
with
the
commodity
uses
of
methyl
bromide
including:
direct
use
of
air
monitoring
data
collected
during
actual
commodity
treatments
with
methyl
bromide
which
is
referred
to
as
the
(
1)
Monitoring
Data
Method;
the
use
of
ISCST3
air
model
referred
to
as
the
(
2)
ISCST3
Modeling
Method;
and
the
use
of
PERFUM
referred
to
as
the
(
3)
PERFUM
Modeling
Method.
Each
method
has
been
a
critical
element
of
the
Agency's
evaluation
of
methyl
bromide
but
the
Agency
also
believes
that
the
PERFUM
approach
best
represents
the
overall
range
of
potential
risks
that
would
be
anticipated
for
the
commodity
uses
of
methyl
bromide
because
it
provides
flexibility
in
that
different
climatic
conditions,
chamber
types,
emission
rates,
and
many
other
factors
can
be
evaluated.
20
(
1)
Monitoring
Data
Method:
In
the
monitoring
data
method,
air
concentrations
are
estimated
using
actual
air
monitoring
data.
In
these
studies,
the
fumigant
is
applied
to
a
chamber,
building,
or
other
areas,
and
air
samplers
positioned
in
and
around
the
treated
area
continuously
sample
the
air
by
pulling
the
air
through
a
filter
(
e.
g.,
charcoal)
which
captures
the
chemical
for
later
analysis.
Sampling
times
can
vary
widely
but
generally
range
from
about
2
to
12
hours,
so
that
the
samples
represent
the
average
air
concentrations
for
the
sampling
intervals
used.
Usually
shorter
times
are
used
at
the
beginning
because
fumigants
can
quickly
volatilize
into
the
atmosphere
and,
for
commodity
uses,
active
aeration
is
often
used
which
enhances
this
occurrence.

There
are
several
uncertainties
associated
with
the
use
of
the
direct
sampling
method
which
limit
its
utility.
First,
the
air
concentrations
represent
only
those
for
the
conditions
under
which
the
study
was
carried
out.
Air
concentrations
around
treated
chambers,
buildings,
or
other
areas
are
influenced
by
a
number
of
factors
including
how
a
chemical
is
applied,
application
rate,
techniques
to
control
emissions
(
e.
g.,
chamber
structure),
and
weather
conditions.
Varying
weather
conditions,
for
example,
can
significantly
change
the
profile
of
air
concentrations
around
a
treated
area;
and
since
there
is
such
a
large
range
of
potential
weather
conditions,
it
is
not
possible
for
these
studies
to
represent
the
entire
range
of
potential
exposures
which
could
result
from
different
weather
situations.
Second,
the
air
concentrations
are
measured
by
fixed
samplers
positioned
at
various
directions
around
the
treated
area,
both
downwind
and
upwind,
as
well
as
at
points
in
between.
Air
concentrations
downwind
will
be
relatively
high
since
the
fumigant
plume
will
be
pushed
by
the
wind
in
that
direction,
while
concentrations
upwind
will
be
low
or
close
to
zero
since
the
plume
is
pushed
by
the
wind
in
the
opposite
direction.
Therefore,
there
can
be
a
very
large
difference
between
upwind
and
downwind
air
concentrations.
For
areas
where
there
is
a
predominant
wind
direction,
averaging
of
the
air
concentrations
from
these
various
samplers
should
not
be
done
since
persons
around
treated
areas
will
generally
be
in
one
location
relative
to
the
wind
and
not
exposed
to
an
average
of
these
concentrations.
Third,
samplers
are
positioned
at
specific
distances
from
the
treated
area,
and
represent
air
concentrations
only
at
those
distances.
Since
air
concentrations
vary
greatly
by
distance,
the
air
concentrations
estimated
from
direct
measures
represent
a
very
narrow
range
of
the
possible
levels
to
which
people
could
be
exposed.
The
available
monitoring
data
are
presented
in
Appendix
D.
Overall
trends
in
the
monitoring
data
have
also
been
used
to
characterize
the
results
calculated
with
modeling
methods
and
are
referenced
as
appropriate.
The
Agency
believes
that
results
based
on
monitoring
data
provide
estimates
of
exposure
and
risk
that
are
representative
of
the
conditions
under
which
the
data
were
collected
and
also
which
suffer
limitations
due
to
the
number
of
samplers
used
and
their
placement.
As
such,
the
Agency
does
not
believe
that
monitoring
data
provide
the
most
informative
approach
for
considering
the
risks
associated
with
methyl
bromide
use
because
other
field
conditions
and
risks
at
different
distances
from
the
source
can
be
evaluated
with
modeling
approaches.
[
Note:
If
desired,
results
based
on
monitoring
data
can
be
evaluated
based
on
the
information
in
Appendices
C,
D,
and
E.
Appendix
C
provides
citations
for
all
monitoring
data.
The
actual
data
are
presented
in
Appendix
D
and
a
summary
of
the
data
in
a
manner
appropriate
for
this
analysis
is
presented
in
Appendix
E.]
21
(
2)
ISCST3
Modeling
Method:
The
ISCST3
modeling
method
uses
the
Agency
model,
Industrial
Source
Complex
Short
Term
(
ISCST3)
coupled
with
input
values
that
describe
emissions
from
treated
chambers,
buildings
or
other
facilities
in
order
to
model
the
range
of
concentrations
which
might
be
found
under
different
conditions
of
application
rate,
weather,
source
size
and
shape
(
e.
g.,
building
size),
and
distances
from
the
treated
building,
structure,
or
other
area.
Before
a
modeling
analysis
can
be
done,
one
of
the
most
important
parameters
for
ISCST3,
the
flux
or
rate
of
pesticide
emissions
from
the
treated
buildings
or
structures
must
be
determined.
As
an
example,
for
commodity
treatments
flux
could
be
expressed
as
a
percentage
of
the
treatment
concentration
that
escapes
over
time
because
the
chamber
or
structure
being
used
for
fumigation
purposes
is
not
completely
sealed.
The
absolute
amount
of
what
escapes
(
i.
e.,
a
fugitive
emission
in
this
case)
is
then
defined
as
the
product
of
the
size
of
the
treated
structure
and
the
treatment
concentration.
In
essence,
flux
represents
how
quickly
the
pesticide
moves
or
volatilizes
into
the
surrounding
atmosphere
from
the
treated
area,
building
or
structure.
Numerous
factors
can
influence
flux
rates
after
commodity­
type
applications
and
these
include
application
rate,
durations
of
treatment,
nature
of
the
media
being
treated,
type
and
efficacy
of
chambers
or
structures
being
used
for
treatment,
and
ventilation
criteria
used
to
evacuate
methyl
bromide
after
treatments
are
completed.
Flux
is
also
difficult
to
determine.
There
are
three
generally
recognized
methods
are
used
to
estimate
flux
from
soil
applications
including
(
1)
the
chamber
method;
(
2)
the
aerodynamic
flux
method;
and
(
3)
the
indirect
flux
method.
While
all
three
techniques
are
generally
considered
appropriate
for
use
in
determining
flux
from
treated
fields,
they
are
generally
not
equally
applicable
to
commodity
situations.
As
such,
the
only
the
principle
method
that
is
applied
typically
for
commodity
and
other
non­
field
uses,
the
indirect
flux
method,
is
described
below
in
any
detail.

ISCST3
Flux
Method:
Indirect
Back­
Calculation
The
method
most
often
used
to
determine
flux
rates
is
the
indirect
or
back­
calculation
method
which
is
described
at
http://
www.
cdpr.
ca.
gov/
docs/
empm/
pubs/
ehapreps/
eh9903.
pdf.
This
method
uses
measured
air
concentrations
from
various
positions
around
structure
or
facility
taken
while
monitoring
a
typical
fumigation.
Using
the
dimensions
of
the
fumigation
chamber,
the
location
of
the
samplers
relative
to
the
fumigation
chamber,
and
weather
information
collected
during
the
period
of
fumigation,
ISCST3
is
run
using
a
nominal
flux
rate
(
usually
0.01
g/
m2­
s
for
area
sources
and
1
g/
s
for
point
sources).
The
results
from
the
ISCST3
run
are
compared
to
the
measured
air
concentrations
and
a
best
fit,
linear
relationship
is
determined.
The
slope
of
the
line
from
this
best
fit
is
the
estimate
flux
rate
from
the
fumigation.

Defining
flux
estimates
for
all
of
the
scenarios
to
be
considered
in
an
assessment
is
necessary
before
ISCST3
can
be
run.
Other
key
inputs
must
also
be
defined
such
as
the
size
and
shape
of
a
treated
chamber
or
structure,
wind
direction,
wind
speed,
and
atmospheric
stability.
ISCST3
calculates
downwind
air
concentrations
using
hourly
meteorological
conditions
that
include
wind
speed
and
atmospheric
stability.
Lower
wind
speeds
and
a
more
stable
atmosphere
generate
higher
the
air
concentrations
closer
to
a
treated
chamber
or
structure
because
emissions
are
not
pushed
as
far
from
a
source
and
diluted
as
much
as
they
would
be
under
more
turbulent
conditions.
Conversely,
if
wind
speed
increases
or
the
atmosphere
is
less
stable,
then
air
concentrations
are
reduced.
Atmospheric
stability
is
essentially
a
measure
of
how
turbulent
the
22
Figure
1:
Illustration
Of
ISCST3
Gaussian
Plume
Approach
atmosphere
is
at
any
given
time.
Stability
is
affected
by
solar
radiation,
wind
speed,
cloud
cover,
and
temperature
among
other
factors.
If
the
atmosphere
is
unstable,
then
more
off­
source
movement
of
airborne
residues
is
possible
without
a
large
increase
in
air
concentrations
because
the
residues
are
carried
up
into
the
atmosphere
and
moved
away
from
the
field
or
other
source,
thereby
lowering
the
air
concentration
in
proximity
to
the
field/
source.
In
the
ISCST3
modeling
method,
to
simplify
modeling
the
transport
of
fumigant
vapors
from
a
source,
a
single
wind
direction,
wind
speed,
and
stability
category
are
used
for
a
given
exposure
duration
for
methyl
bromide
which
is
consistent
with
the
HEC
duration.
The
Agency
has
not
determined
if
a
particular
set
of
meteorological
conditions
should
be
used
for
regulatory
purposes,
so
results
were
developed
based
on
a
variety
of
different
conditions.
A
range
of
atmospheric
conditions
representing
the
continuum
from
relatively
stable
(
low
windspeed
&
calm)
to
unstable
conditions
(
high
windspeeds
&
unsettled)
was
evaluated
using
ISCST3
(
Figure
1).
Under
relatively
stable
atmospheric
conditions,
the
modeling
produces
results
that
represent
highly
exposed
individuals
(
i.
e.,
ISCST3,
as
used,
results
in
exposure
estimates
at
the
upper
percentiles
of
an
anticipated
exposure
distribution).
Two
key
inputs
are
the
basis
for
this
conclusion.
First,
only
a
constant
downwind
direction
is
considered
with
no
fluctuation
the
way
ISCST3
was
used
in
the
previous
assessment
(
see
D316326).
This
type
of
situation
would
be
highly
unlikely
in
any
outdoor
environment.
Secondly,
the
quantitative
inputs
used
to
define
atmospheric
stability
conditions
were
also
held
constant
which
also
will
not
occur
in
an
outdoor
environment.
Conversely,
unsettled
conditions
may
reduce
risk
estimates
but
it
is
believed
that
even
these
conditions
can
result
in
conservative
estimates
because
wind
direction
is
constrained
to
a
single
vector
over
the
period
of
concern.
23
ISCST3
can
provide
useful
results
because
it
allows
estimation
of
air
concentrations
reflecting
different
conditions
based
on
changing
factors
such
as
application
rates,
structure
sizes,
downwind
distances,
wind
and
weather
conditions,
and
other
factors,
which
cannot
be
done
using
the
monitoring
data
method.
Results
for
the
various
major
use
categories
for
methyl
bromide,
including
for
commodity
uses,
based
on
the
ISCST3
Modeling
Method
were
included
in
the
previous
version
of
the
risk
assessment
[
see
document
D316326
available
at
www.
Regulations.
gov
under
the
methyl
bromide
docket
(
EPA­
HQ­
OPP­
2005­
0123)].
For
the
purposes
of
this
assessment,
results
based
on
ISCST3
have
not
been
recalculated
because
the
Agency
believes
that
a
tiered
approach
best
represents
the
risks
associated
with
methyl
bromide
commodity
uses
and
that
PERFUM
results
represent
more
refined
risk
estimates
(
see
description
below).
Also,
since
the
latest
methyl
bromide
assessment
was
completed
(
D316326)
the
Agency
has
also
revised
its
inputs
to
reflect
the
most
recently
available
use
information
and
does
not
want
to
expend
additional
resources
for
completing
an
ISCST3
analysis
when
PERFUM
results
will
be
available
(
e.
g.,
chamber
or
structure
sizes).
Finally,
the
flux
estimates
in
this
assessment
have
not
been
quantitatively
defined
by
the
Agency
using
the
indirect
flux
method.
This
method
has
been
used
by
CADPR
to
define
ranges
of
loss
rates
upon
which
their
commodity
permit
conditions
for
methyl
bromide
use
have
been
based.
These
represent
a
range
of
possible
fumigation
events
but
the
breadth
of
possible
scenarios
can
be
much
greater.
As
such,
a
broad
range
of
performance
criteria
based
on
information
obtained
from
several
stakeholders
(
e.
g.,
APHIS
PPQ,
DPR
permit
conditions,
and
general
commodity
treatment
schedules)
has
been
used
to
define
the
flux
values
used
for
this
assessment.
These
are
expressed
as
a
percentage
loss
from
a
treatment
and
are
categorized
in
one
of
two
ways
including
(
1)
during
treatment
­
which
represents
how
much
a
chamber
may
leak
during
use
(
i.
e.,
1
to
50%
of
total
administered
has
been
used
to
represent
this,
varies
with
quality
of
chamber)
and
(
2)
during
aeration
­
which
represents
the
percentage
of
material
purposefully
removed
from
a
chamber
after
treatment
is
complete
(
i.
e.,
50
to
99%
of
total
administered
has
been
used
to
represent
this,
again
varies
with
quality
of
the
chamber).
[
Note:
DPR
calculated
commodity
flux
rates
using
the
back­
calculation
method
have
been
verified
by
the
Agency.
These
values
have
been
used
for
risk
characterization
purposes
in
order
to
evaluate
the
flux
inputs
used
by
the
Agency
herein.
See
the
PERFUM
assessment
described
below
for
further
details.]

(
3)
PERFUM
Modeling
Method:
The
monitoring
data
and
ISCST3
methods
described
above
are
deterministic
in
nature
and
the
ISCST3
method,
by
design,
provides
high­
end
point
estimates
of
exposure
and
risk.
OPP
is
coordinating
with
EPA's
Office
of
Air,
the
CDPR,
and
others
to
evaluate
and
implement
the
PERFUM
modeling
approach
based
on
ISCST3
which
incorporates
actual
meteorological
data
and
refined
flux
inputs
which
are
based
on
available
data
and
other
information.
[
Note:
As
indicated
above,
the
Agency
would
also
evaluate
submissions
based
on
similar
modeling
approaches
if
available
although
it
does
not
know
of
an
alternative
approach
which
is
currently
available
for
developing
distributions
of
exposure
that
result
from
commodity
fumigations.]
PERFUM
allows
users
to
develop
an
understanding
of
the
distributions
of
potential
bystander
exposures
around
the
perimeter
of
a
treatment
facility
or
structure
and
thus
more
fully
characterize
the
range
of
risks
resulting
to
bystanders
from
commodity
treatments
This
is
a
modification
from
the
previously
completed
assessments
because
ISCST3
was
used
in
a
deterministic
approach
and
PERFUM,
or
other
similar
tools
were
not
available.
PERFUM
has
now
been
modified
to
be
capable
of
defining
a
source
term
for
commodity
type
applications
(
i.
e.,
24
PERFUM
Main
Model
ISCST3
Subroutine
PERFUM
Subroutines
(
tabulate
results)
After
Each
Day
Output
Results
After
5
Years
is
Completed
Cycles
1825
x
Figure
2:
Operational
Flowchart
For
PERFUM
Figure
3:
Example
PERFUM
Receptor
Grid
PERFUM
V2.1.2
is
available
at
http://
www.
sciences.
com/
perfum/
index.
html).
For
comparative
purposes,
PERFUM
V1.1
is
available
at
http://
www.
epa.
gov/
opphed01/
models/
fumigant/
.
ISCST3
is
an
integral
part
of
the
PERFUM
model
(
see
Figure
2
below
and
for
further
details
see
http://
www.
epa.
gov/
scipoly/
sap/
2004/
index.
htm).
The
basic
physics
and
code
of
ISCST3
remain
unchanged.
PERFUM
essentially
provides
ISCST3
with
daily
meteorological
data
over
the
selected
5
years
as
well
as
user
defined
flux
inputs.
PERFUM
then
uses
this
information
to
create
distributional
outputs
for
receptor
locations
around
the
treated
structure
(
see
Figure
3).
25
Figure
4:
Distribution
of
Daily
Average
Windspeeds
At
Selected
Meteorological
Stations
PERFUM
V2.1.2
has
an
algorithm
that
establishes
the
receptor
grid
which
differs
from
PERFUM
V1.1
where
the
grid
locations
were
hardwired.
The
maximum
distance
allocated
is
still
1440
meters
from
the
edge
of
the
source
in
question.
Since
actual
meteorological
data
are
integrated
into
PERFUM
for
each
analysis,
data
representative
of
the
locations
where
methyl
bromide
use
occurs
were
identified
and
used
in
the
analysis.
For
example,
major
commodity
uses
occur
in
the
coastal
regions
of
Florida
and
California
at
ports
and
significant
levels
of
commodity
production
also
occurs
in
these
coastal
regions
so
data
from
these
locales
were
used.
In
addition,
data
from
Flint
Michigan
were
also
used
to
represent
inland
uses
of
methyl
bromide.
The
following
locations
and
sources
of
meteorological
data
were
used
in
this
assessment:

°
Ventura
California
(
Source:
CIMIS
or
California
Irrigation
Management
Information
System)
to
represent
coastal
California
locations;
°
Flint
Michigan
(
Source:
NWS
or
National
Weather
Service)
to
represent
central
Michigan
and
other
upper
midwest
locations;
and
°
Tallahassee
Florida
(
Source:
NWS
or
National
Weather
Service)
to
represent
inland
Florida
locations.

In
this
assessment,
5
years
or
1825
days
of
meteorological
data
were
considered
in
each
calculation.
Ventura
data
were
in
the
range
of
1995
through
1999
but
Tallahassee
and
Flint
were
in
the
late
1980s
through
early
1990s.
[
Note:
Please
refer
to
the
SAP
background
documents
for
PERFUM
for
further
information
concerning
these
data
including
how
they
were
processed
for
incorporation
into
PERFUM
and
any
quality
control
issues
related
to
these
data
(
http://
www.
epa.
gov/
scipoly/
sap/
2004/
index.
htm).]
Figure
4
provides
a
comparison
of
the
distributions
of
daily
average
windspeeds
for
selected
stations
in
California
and
Florida.
These
can
be
used
to
help
characterize
the
deterministic
assessments
and
to
illustrate
different
PERFUM
results
for
the
different
stations.
[
Note:
As
an
example,
CDPR
regulated
Methyl
bromide
at
1.4
m/
s
windspeed.]
26
References
&
Sources
Used
For
PERFUM
Analysis:
The
domestic
treatment
of
commodities
is
an
extremely
varied
undertaking
because
of
the
nature
of
the
commodities
being
treated,
the
nature
of
the
pest
complexes
being
controlled,
the
amount
of
daily
throughput
required,
and
the
ranges
of
facilities
(
e.
g.,
tarped
chambers)
and
processes
used
for
routine
treatments
(
e.
g.,
active
aeration).
Because
the
use
of
methyl
bromide
on
commodities
is
so
varied,
the
Agency
considered
a
number
of
sources
for
information
pertaining
to
these
types
of
applications.
The
key
sources
include:

C
Reference
Manual:
Methyl
Bromide
Commodity
Fumigation.
CDPR.
August
8,
1994
[
available
at:
http://
www.
cdpr.
ca.
gov/
docs/
enfcmpli/
manuals/
mbcomfum.
pdf]

C
United
States
Department
of
Agriculture,
Agricultural
Plant
Health
Inspection
Service,
Plant
Protection
and
Quarantine
­
Treatment
Manual,
Last
Updated
2/
6/
06
[
available
at:
http://
www.
aphis.
usda.
gov/
ppq/
manuals/
port/
Treatment_
Chapters.
htm.]

C
2005
Annual
International
Research
Conference
on
Methyl
Bromide
Alternatives
and
Emissions
Reductions,
Conference
program
and
presentations
[
available
at:
http://
mbao.
org/
2005/
0006%
202005%
20Conf%
20Program.
pdf.]

Treatment
Types
&
Exposure
Scenarios:
Based
on
these
documents,
comments
received
in
the
Phase
3
public
comment
period,
and
interactions
with
various
stakeholders
the
Agency
has
developed
a
series
of
input
parameters
for
the
PERFUM
modeling
which
has
been
completed
in
order
to
assess
the
risks
associated
with
the
commodity
uses
of
methyl
bromide.
These
factors
stipulate
the
nature
of
the
buildings,
chambers,
or
structures
being
treated;
application
rates
and
treatment
durations;
and
emission
rates
and
factors.
A
compilation
of
these
factors
lead
to
categorization
of
the
major
use
patterns,
for
risk
assessment
purposes,
into
the
following
major
scenarios
that
include:

C
Scenario
1
­
Chamber
During
Treatment:
This
scenario
represents
what
leaks
from
a
chamber
during
treatment
(
also
referred
to
as
a
fugitive
emission)
where
the
desire
is
to
retain
methyl
bromide
according
to
the
CxT
(
concentration
x
time)
schedules
until
a
desired
level
of
efficacy
is
reached.

C
Scenario
2
­
Aeration
With
No
Stack:
This
scenario
represents
what
is
emitted
from
a
chamber
after
treatment
is
complete
and
the
desire
is
to
remove
remaining
methyl
bromide
as
quickly
as
possible.
In
this
scenario,
methyl
bromide
is
purposely
vented
but
there
is
no
stack
available
to
transport
emissions
further
up
into
the
atmosphere
so
the
results
reflect
a
warehouse
or
other
structure
that
is
treated
where,
for
aeration,
a
door
is
opened.

C
Scenario
3
­
Aeration
With
Stack:
This
scenario
represents
what
is
emitted
from
a
chamber
after
treatment
is
complete
and
the
desire
is
to
purposely
vent
remaining
methyl
bromide
as
quickly
as
possible.
In
this
scenario,
methyl
bromide
is
purposely
vented
through
a
stack
to
transport
emissions
further
up
into
the
atmosphere
to
reduce
buffer
distances
and
enhance
dilution.
The
results
reflect
a
warehouse
or
other
structure
that
is
treated
where
a
stack
is
on
the
roof
for
ventilation
purposes.
The
impacts
of
near
building
downwash
effects
are
accounted
for
in
this
scenario.
27
C
Scenario
4
­
Aeration
With
Portable
Stack
Not
Near
Building:
This
scenario
represents
an
APHIS
PPQ
practice
where
methyl
bromide
is
vented
through
portable
tubing
to
a
stack
in
an
area
adjacent
to
a
treated
structure
or
chamber.
The
scenario
represents
what
is
emitted
from
a
chamber
after
treatment
is
complete
and
the
desire
is
to
purposely
vent
remaining
methyl
bromide
as
quickly
as
possible.
In
this
scenario,
methyl
bromide
is
purposely
vented
through
a
stack
to
transport
emissions
further
up
into
the
atmosphere
to
reduce
buffer
distances
and
enhance
dilution.
The
results
reflect
a
warehouse
or
other
structure
that
is
treated
where
methyl
bromide
is
transported
to
a
portable
stack,
typically
within
200
feet
of
the
facility
for
ventilation
purposes.
The
near
building
downwash
effects
are
minimized
because
of
the
placement
of
the
stacks
in
this
scenario.

C
Scenario
5
­
Aeration
With
Mobile
Ground
Level
Source
Not
Near
Building:
This
scenario
represents
an
APHIS
PPQ
practice
where
methyl
bromide
is
vented
through
portable
tubing
where
the
output
is
laid
on
the
ground
in
an
area
adjacent
to
a
treated
structure
or
chamber.
The
scenario
represents
what
is
emitted
from
a
chamber
after
treatment
is
complete
and
the
desire
is
to
purposely
vent
remaining
methyl
bromide
as
quickly
as
possible.
In
this
scenario,
methyl
bromide
is
purposely
vented
through
the
tubing
to
transport
emissions
away
from
the
chamber
or
facility
to
reduce
buffer
distances.
The
results
reflect
a
warehouse
or
other
structure
that
is
treated
where
methyl
bromide
is
transported
through
tubing
with
the
output
typically
within
200
feet
of
the
facility
for
ventilation
purposes.
The
near
building
downwash
effects
are
minimized
because
of
the
placement
of
the
vent
tubes
in
this
scenario.

PERFUM
Model
Inputs:
In
order
to
assess
the
potential
levels
of
exposures
that
could
be
associated
with
the
5
exposure
scenarios
described
above,
the
Agency
has
developed
a
series
of
input
parameters
for
the
PERFUM
modeling
that
is
meant
to
bracket
the
range
of
possible
exposures
associated
with
the
methyl
bromide
treatment
of
commodities
under
various
common
use
practices.
The
modeled
conditions
are
also
thought
to
encompass
and
expand
upon
the
permit
conditions
currently
used
in
California
to
mitigate
commodity
applications.
[
Note:
A
discussion
of
how
these
inputs
translate
to
common
commodity
practices
is
described
below
in
the
results
and
characterization
sections
­
see
below
for
further
information
concerning
such
specific
situations.]
The
factors
which
have
been
used
include:

C
Treatment
Concentrations
(
derived
from
labels
&
CxT
tables):
­
Food
Commodities:
1
and
4
lb
ai/
1000
cubic
feet;
and
­
Other
Materials
(
e.
g.,
logs):
9
and
15
lb
ai/
1000
cubic
feet.

C
Retention
&
Emission
Rates
(
expressed
as
%
of
treatment
concentrations):
­
Chambers
During
Treatment
(
Scenario1):
1,
5,
10,
25,
and
50%
of
treatment
concentration;
and
­
For
Aeration
(
Scenarios
2­
5):
50,
75,
90,
95,
99,
and
100%
of
treatment
concentration
is
released
and
varies
based
on
how
airtight
the
chamber
is
during
active
treatment
or
how
much
is
absorbed
by
the
materials
or
commodities
being
treated.
[
Note:
DPR
Permit
conditions
establish
loss
rates
during
treatment
from
0.2
to
3.0
lb
mebr/
1000
ft3
and
during
aeration
from
0.4
to
6
lb
mebr/
1000
ft3.]
28
C
Chamber/
Structure
Volume:
­
Small
scale:
1000,
2000,
5000
cubic
feet;
­
Mid
scale:
10000,
25000,
50000
cubic
feet;
and
­
Large
scale:
100000,
250000,
500000,
750000,
1000000
cubic
feet.

C
Chamber/
Structure
Height:
­
Small
scale:
1000
cu.
ft
=
10
feet
tall,
2000
cu.
ft.
=
12
feet
tall,
5000
cu.
ft.
=
17
feet
tall;
­
Mid
scale:
25
feet
tall
­
Large
scale:
75
feet
tall
C
Stack
&
Release
Heights:
­
All
fixed
stack
heights
=
stack,
10
feet
above
roof
of
chambers
or
structures
[
Note
absolute
release
height
then
varies
when
added
with
specific
building
height]
­
Portable
stack
height
=
50
feet
C
Active
Air
Exchange
Rates:
­
1
air
exchange/
minute;
­
0.5
air
exchanges/
minute;
and
­
0.05
air
exchanges/
minute.
[
Note:
Fixed
fan
capacities
=
2000
ft/
minute
for
structures
up
to
and
including
100,000
cubic
feet.
For
larger
structures
a
fan
velocity
of
5000
ft/
minute
was
used.
These
have
been
empirically
observed
by
CDPR
under
actual
use
conditions.
For
no
stack
scenarios,
aeration
is
passive
and
it
is
treated
as
an
area
source
in
PERFUM.]

C
Stack
Diameters:
­
PERFUM
can
only
accommodate
a
single
stack
so
the
diameters
are
varied
in
order
to
achieve
the
proper
cross
sectional
ventilation
areas
for
each
combination
of
chamber/
structure
size
and
air
exchange
value.
The
results
for
larger
chambers
or
high
concentration
treatments,
therefore,
may
be
based
on
very
large
diameter
stacks
which
would
not
occur
in
reality
to
achieve
proper
ventilation
(
i.
e.,
0.2
m
to
5
m).
Under
actual
conditions,
multiple
stacks
would
be
used
in
order
to
achieve
target
air
exchange
rates.
The
architecture
of
PERFUM
requires
that
these
analyses
be
done
in
this
manner.
This
approach
is
not
expected
to
be
a
negative
bias
in
the
results.
In
fact,
this
approach
is
likely
a
conservative
method
because
all
emitted
methyl
bromide
is
forced
out
at
one
location
making
the
predicted
distances
higher.

C
Treatment
Frequency
&
Emission
Profiles:
­
A
number
of
frequency
and
emission
profiles
were
considered
in
order
to
simulate
the
practices
associated
with
methyl
bromide
commodity
use.
In
many
applications
(
e.
g.,
import
grapes)
the
active
application
duration
is
a
matter
of
a
couple
of
hours
or
so
followed
by
a
quick
ventilation
process
which
takes
on
the
order
of
15
minutes
or
less.
In
some
cases,
multiple
chambers
are
being
released
in
sequence
because
of
the
number
of
batches
required
to
keep
up
with
throughput
requirements
at
ports
and
other
facilities.
Finally,
there
are
other
cases
where
the
treated
materials
(
e.
g.,
logs
and
timber)
offgas
for
up
to
several
days,
but
where
most
material
comes
off
in
the
first
day
or
so.
Based
on
this
information,
the
Agency
considered
4
frequency
and
emission
profiles
in
the
assessment:
29
­
1
hour,
single
emission:
based
on
a
single
application
and
short­
lived
emission
period
such
as
15
minutes.
Actual
modeling
used
a
1
hour
emission
profile,
as
the
smallest
interval
permitted
in
PERFUM
is
1
hour.
As
the
HEC
used
in
the
assessment
is
an
8
hour
endpoint,
a
1
hour
emission
profile
was
thought
to
be
a
more
accurate
comparison;

­
4
hour,
single
emission:
based
on
a
single
application
and
short­
lived
emission
period
such
as
15
minutes.
As
with
the
1
hour,
single
emission
scenario,
a
1
hour
emission
profile
was
used
for
the
release.
This
release
was
then
followed
by
3
hours
without
a
release.

­
4
hour,
multiple
emissions:
based
on
multiple,
sequential
emissions
and
short­
lived
emission
periods
such
as
15
minutes.
This
is
similar
to
the
1
hour,
single
emission
scenario,
except
the
resulting
concentrations
were
averaged
over
a
4
hour
period.
This
scenario
is
used
model
sequential
batches
resulting
in
multiple
emissions
events
that
are
occurring
during
high
throughput
periods
of
activity
not
uncommon
at
many
ports
for
seasonal
commodities;
and
­
24
hour,
continuous
single
emission:
based
on
a
single
application
and
an
extended
emission
period
from
materials
that
may
absorb
methyl
bromide
residues
(
e.
g.,
logs
and
timbers),
the
duration
of
most
concern
is
the
first
24
hours.
The
basis
of
this
assessment
is
that
the
majority
of
methyl
bromide
emissions
would
be
expected
in
that
interval.

C
Target
Concentrations
(
HECs/
UF):
­
8
Hour
NOAEL
HEC
(
30
ppm)
and
Uncertainty
Factors
30,
10,
3,
and
1
;
and
­
24
Hour
NOAEL
HEC
(
10
ppm)
and
Uncertainty
Factors
30,
10,
3,
and
1
for
selected
scenarios
where
offgassing
from
a
treated
commodity
(
e.
g.,
logs
or
timber)
would
be
expected
over
extended
periods
of
time.
[
Note:
The
8
hour
duration
is
longer
than
the
durations
associated
with
the
frequency
and
emission
profiles
described
above.
However,
based
on
the
available
hazard
information,
this
is
the
shortest
recommended
duration
for
an
HEC
the
Agency
believes
to
be
justifiable.]

PERFUM
calculates
outputs
based
on
each
day's
worth
of
meteorological
data
and
the
result
is
illustrated
by
Figure
5
which
shows
the
distances
from
the
commodity
facility
(
i.
e.,
chamber
or
building)
where
airborne
concentrations
meet
a
threshold
of
concern
around
its
perimeter
(
i.
e.,
the
irregularly
shaped
line).
The
concentric
circle
represents
an
example
95th
percentile
distance
value
around
the
perimeter
(
i.
e.,
the
distance
for
that
day
where
MOEs
are
not
of
concern
for
95%
of
those
exposed).
The
cross
hatch
area
represents
the
locations
where
distances
exceed
the
95th
percentile
value
(
i.
e.,
MOEs
are
of
concern
at
these
distances
for
5%
of
the
exposed
population).
These
exceedances
have
been
examined
using
the
PERFUM
MOE
program
and
other
approaches
(
see
SAP
site
for
more
details)
in
order
to
provide
risk
managers
with
a
better
understanding
of
how
many
factors
can
influence
predicted
buffer
distances,
including
how
predicted
buffers
change
with
changing
margins
of
exposure.

PERFUM
generates
the
type
of
output
illustrated
by
Figure
5
for
each
day
over
a
5
year
period
(
i.
e.,
1825
days)
then
summarizes
the
information
by
providing
two
types
of
results
that
include
the
"
Maximum
Buffer"
distance
and
the
"
Whole
Field
Buffer"
distance.
Each
is
reported
as
a
distribution.
The
"
Maximum
Buffer"
distribution
is
based
on
the
maximum
distance
needed
to
reach
a
threshold
level
of
concern
(
i.
e.,
HEC
adjusted
by
uncertainty
factor)
calculated
using
30
Figure
5:
Example
Daily
PERFUM
Output
PERFUM
for
each
day
(
i.
e.,
a
distribution
of
the
farthest
single
points
on
the
irregular
line
for
each
day).
This
results
in
a
distribution
that
contains
1825
values
and
in
this
assessment,
the
results
have
been
reported
for
selected
percentiles
from
those
distributions.
The
"
Whole
Field
Buffer"
is
also
based
on
values
from
each
day,
except
the
distances
on
which
the
distribution
is
based
include
those
on
each
spoke
where
the
threshold
concentration
is
achieved
for
each
day
(
i.
e.,
a
distribution
of
the
distances
on
all
spokes
on
the
irregular
line
where
it
intersects
each
spoke).
The
number
of
values
in
the
distributions
vary
and
are
based
on
1825
days
(
or
more
intervals
if
averaging
time
is
less
than
24
hours)
multiplied
by
the
number
of
spokes
around
the
field
which
relates
to
field
size.
As
with
the
"
Maximum
Buffer"
distances,
results
from
selected
percentiles
from
the
distribution
have
been
reported.

6.1.1.2
Bystander
Exposures
And
Risks
From
Known
Sources
The
risks
for
bystanders
from
various
types
of
known
sources
are
presented
in
this
section
(
e.
g.,
commodity
chamber,
etc.).
For
the
purposes
of
this
assessment,
known
sources
are
thought
to
represent
a
point
source
from
a
single
application
(
e.
g.,
a
stack
on
the
roof
of
a
commodity
treatment
chamber)
or
an
area
source
when
no
stack
emissions
are
considered
(
e.
g.,
an
opened
door
or
a
stack
used
to
dissipate
residues
from
a
treated
commodity
chamber).
Because
of
the
refinements
offered
by
the
PERFUM
modeling
approach,
it
is
believed
results
based
on
this
method
should
be
considered
as
the
most
appropriate
for
evaluating
the
risks
associated
with
commodity
uses
methyl
bromide.
However,
it
should
be
noted
that
results
from
all
of
the
approaches
described
above
were
used
to
characterize
the
range
of
risks
associated
with
methyl
bromide.
31
The
monitoring
data
which
are
applicable
to
the
commodity
uses
of
methyl
bromide
are
presented
summarized
in
Appendices
D
and
E
of
this
document.
The
data
are
resultant
from
various
monitoring
studies,
predominantly
conducted
by
CDPR
staff
in
facilities
thought
of
as
traditional
commodity
treaters
and
also
larger
facilities
like
a
rice
mill.
Previously,
these
larger
scale
treatments
were
considered
to
be
more
of
an
industrial
nature
but
it
is
clear
that
these
data
are
also
applicable
to
the
commodity
uses
of
methyl
bromide.
The
exposure
concentrations
and
associated
risk
estimates
that
have
been
calculated
based
on
the
commodity
and
applicable
industrial
data
are
presented
in
Table
5
below.
The
results
indicate
a
risk
concern
for
acute
exposures
in
proximity
to
a
treatment
chamber
or
facility.
Generally,
short­
term
exposures
are
not
of
concern.
If
short­
term
exposures
were
calculated
using
a
24
hour
HEC
of
1
ppm
then
MOEs
would
be
of
concern
but
this
is
likely
to
be
an
overestimate
of
risk.
Based
on
this
information,
however,
it
is
clear
that
acute
exposures
are
of
more
concern
and
thus
any
mitigation
of
those
exposures
would
similarly
reduce
short­
term
exposures
thus
further
decreasing
concerns
over
short­
term
exposures.
As
such,
the
Agency
has
focused
on
evaluating
the
potential
risks
associated
with
acute
exposure
patterns.

Table
5:
Acute
and
Short­
term
Bystander
Risks
Calculated
Based
On
Methyl
Bromide
Monitoring
Data
After
Commodity
And
Applicable
Industrial
Treatments
Data
Type
Location
[
Methyl
Bromide]
(
ppm)
MOEs*

Maximum
Mean
Acute
Short­
term
Commodity
acute
~
320
ft.
mean
­
range
6.79
0.10
4.4
44
Industrial
(
fenceline
monitoring)
<
200
ft
1.10
0.12
27
37
200
to
700
ft
0.09
0.01
323
400
700
to
1000
ft
0.05
0.01
625
400
>
1000
ft
0.01
0.002
3800
2095
*
Target
MOE
or
UF
=
30,
MOEs
calculated
using
8
hr
HEC
(
30
ppm
for
acute
and
4.4
ppm
for
short­
term).
Air
concentrations
are
time­
weighted
averages
of
differing
durations
from
5
hours
or
so
to
a
24
hr
twa
but
use
of
a
24
hour
HEC
would
lead
to
a
likely
overestimation
of
risks
based
on
the
nature
and
frequency
of
commodity
uses
for
the
vast
majority
of
expected
exposure
scenarios.

The
ISCST3
model
(
i.
e.,
Industrial
Source
Complex,
Short­
term
Model,
V3)
was
also
used
in
the
earlier
assessment
(
D316326)
to
calculate
margins
of
exposure
at
downwind
distances
under
weather
conditions
that
varied
from
calm
to
a
turbulent
atmosphere.
Results
were
as
expected
with
receptors
close
to
the
field
(
i.
e.,
100s
of
meters
in
some
cases)
having
risk
concerns
while
those
further
away
or
those
in
a
more
turbulent
atmosphere
had
less
overall
risk
concerns.
In
some
cases,
risks
were
not
of
concern
even
when
directly
adjacent
to
the
treatment
area.
Revised
ISCST3
risk
estimates
were
not
recalculated
for
this
assessment
since
the
PERFUM
model
has
been
revised
and
the
Agency
believes
that
it
offers
a
more
refined
estimate
of
risks
since
its
calculations
are
based
on
5
years
of
weather
data
as
opposed
to
the
deterministic
approach
that
has
been
used
with
ISCST3
(
i.
e.,
fixed
downwind
direction,
windspeed,
and
stability
class
­
i.
e.,
level
of
turbulence).
32
The
Agency
believes
the
PERFUM
Modeling
Method
provides
the
most
refined,
scientifically
defensible
approach
for
calculating
and
characterizing
risks
because
it
incorporates
actual
weather
data,
and
it
links
flux
profiles
to
the
appropriate
time
of
day
when
calculating
results.
It
also
uses
as
its
core
processor
the
proven
technology
of
ISCST3.
The
remainder
of
this
section
presents
the
potential
risks
for
bystanders
which
have
been
calculated
using
the
PERFUM
model
for
those
downwind
of
commodity
treatments.
A
large
number
of
model
calculations
have
been
completed
based
on
the
factors
described
above
but
for
the
purposes
of
this
assessment
the
Agency
has
focused
on
summarizing
the
results
that
are
most
applicable
to
the
commodity
uses
of
methyl
bromide
that
are
subjected
to
the
tolerance
reassessment
requirements
of
2006.
Also,
the
Agency
has
limited
the
numbers
of
results
that
have
been
summarized
by
evaluating
results
for
Ventura
California
and
application
rates
of
1
and
4
lb/
1000
cubic
feet
as
well
as
other
factors.
The
number
of
permutations
that
are
possible
based
on
the
input
variables
described
above
and
that
have
been
summarized
for
the
purposes
of
this
assessment
are
presented
in
Table
6
below.
[
Note:
PERFUM
outputs
are
available
for
the
various
combinations
described
in
Table
6.
These
are
available
for
review
but
are
not
included
in
this
assessment,
per
se.
The
2000
or
so
combinations
that
have
been
summarized
by
the
Agency
are
included
as
summary
documents
in
the
form
of
appendices
to
this
assessment.
The
appendices
only
contain
a
summary
of
the
PERFUM
outputs
and
not
the
actual
output
files.]

Table
6:
PERFUM
Model
Permutations
Considered
In
Analysis
Of
Methyl
Bromide
Commodity
Uses
#
Weather
Sources
#
UF
#
Durations
#
Appl
.
Rate
#
Aeration
Types
#
Structures
(
ft3)
#
Percent
Emitted
#
PERFUM
Outputs
Total
3
4
4
4
10
11
8
2
~
300,000*

*
Indicates
possible
number
of
iterations
of
PERFUM
model
output.
These
estimates
have
all
been
calculated
and
are
available
as
PERFUM
output
files
for
interested
parties.
For
the
purposes
of
this
assessment,
~
2000
different
combinations
were
summarized
based
on:
Ventura
CA
weather,
1&
4
lb/
ft3
rates,
5
aeration
types,
5
structure
sizes,
10
percent
emitted
values,
and
2
PERFUM
output
types.

The
PERFUM
outputs
have
been
summarized
in
Appendix
F
for
each
combination
described
in
Table
6.
Appendix
F
contains
21
subappendices
which
are
described
below.
Twenty
of
these
are
data
files
that
represent
a
specific
combination
of
exposure
duration,
application
rate,
and
aeration
type
and
one
file
is
a
summary
analysis
file.
In
each
of
the
20
data
files
there
are
results
for
possible
100
combinations
based
on
changes
in
structure
size
(
5),
percent
emitted
(
10),
and
PERFUM
outputs
(
2).
Appendix
F
includes
the
following:

°
Appendix
F1.
Ventura.
F301Hr1lbMS05:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
of
0.05
times/
minute.

°
Appendix
F1.
Ventura.
F301Hr1lbMSFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
based
on
full
exit
velocity
of
1
time/
minute.
33
°
Appendix
F1.
Ventura.
F301Hr1lbNS:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
and
results
for
no
stack
(
i.
e.,
opening
a
door).

°
Appendix
F1.
Ventura.
F301Hr1lbPortFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
portable
stack
results,
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F1.
Ventura.
F301Hr1lbPPQFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
PPQ­
type
emissions
(
i.
e.,
a
tube
lying
on
its
side
in
a
secured
flat
area),
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F2.
Ventura.
F301Hr4lbMS05:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
of
0.05
times/
minute.

°
Appendix
F2.
Ventura.
F301Hr4lbMSFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
based
on
full
exit
velocity
of
1
time/
minute.

°
Appendix
F2.
Ventura.
F301Hr4lbNS:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
and
results
for
no
stack
(
i.
e.,
opening
a
door).

°
Appendix
F2.
Ventura.
F301Hr4lbPortFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
portable
stack
results,
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F2.
Ventura.
F301Hr4lbPPQFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
1
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
PPQ­
type
emissions
(
i.
e.,
a
tube
lying
on
its
side
in
a
secured
flat
area),
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F3.
Ventura.
F304Hr1lbMS05:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
of
0.05
times/
minute.

°
Appendix
F3.
Ventura.
F304Hr1lbMSFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
based
on
full
exit
velocity
of
1
time/
minute.

°
Appendix
F3.
Ventura.
F304Hr1lbNS:
contains
a
summary
of
the
results
using
Ventura
CA
34
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
and
results
for
no
stack
(
i.
e.,
opening
a
door).

°
Appendix
F3.
Ventura.
F304Hr1lbPortFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
portable
stack
results,
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F3.
Ventura.
F304Hr1lbPPQFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
1
lb/
1000
ft3,
PPQ­
type
emissions
(
i.
e.,
a
tube
lying
on
its
side
in
a
secured
flat
area),
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F4.
Ventura.
F304Hr4lbMS05:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
of
0.05
times/
minute.

°
Appendix
F4.
Ventura.
F304Hr4lbMSFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
minimum
stack
height
results,
and
an
air
exchange
rate
based
on
full
exit
velocity
of
1
time/
minute.

°
Appendix
F4.
Ventura.
F304Hr4lbNS:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
and
results
for
no
stack
(
i.
e.,
opening
a
door).

°
Appendix
F4.
Ventura.
F304Hr4lbPortFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
portable
stack
results,
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
Appendix
F4.
Ventura.
F304Hr4lbPPQFullEV:
contains
a
summary
of
the
results
using
Ventura
CA
weather
data,
an
uncertainty
factor
=
30,
4
hour
emission,
an
application
rate
of
4
lb/
1000
ft3,
PPQ­
type
emissions
(
i.
e.,
a
tube
lying
on
its
side
in
a
secured
flat
area),
and
an
air
exchange
rate
based
on
a
full
exit
velocity
of
1
time/
minute.

°
AppendixF5.
Analysis:
contains
a
summary
of
the
2000
PERFUM
results.[
Note:
This
appendix
also
contains
a
summary
table
that
provides
risk
calculations
based
on
the
data
where
the
target
uncertainty
factor
of
30
has
been
altered
to
illustrate
how
risks
change
with
varying
distances.]
35
It
should
be
acknowledged
that
a
myriad
of
micro­
environmental
conditions
and
factors
can
impact
how
methyl
bromide
will
both
volatilize
and
disperse
from
any
given
commodity
treatment
on
any
given
day.
With
this
premise,
it
would
be
logical
to
evaluate
basic
factors
which
could
influence
dispersion
(
e.
g.,
temperature,
absorptive
properties
of
chambers,
etc.)
and
also
micro­
climates
(
e.
g.,
topography,
downdraft
potential,
etc.)
and
thus
ultimately
impact
results.
However,
PERFUM
cannot
easily
address
specific
changes
in
many
of
these
factors
because
it
is
not
a
1st
Principles
Model
where
the
approach
would
be
to
build
a
predictive
tool
from
basic
fate
characteristics.
Instead,
PERFUM
is
an
empirical
model
which
utilizes
user
inputs
in
this
case
that
have
been
defined
based
on
empirical
monitoring
data
and
use
information
along
with
actual
meteorological
data
to
predict
results.
Since
such
data
are
the
basis
for
the
PERFUM
predictions
it
follows
that
results
based
on
empirical
monitoring
and
those
calculated
with
PERFUM
would
be
similar
(
see
guidance
pertaining
to
air
model
validation
at
http://
www.
epa.
gov/
scram001/
guidance/
guide/
appw_
03.
pdf
for
additional
information).

It
should
also
be
acknowledged
that
the
nomenclature
incorporated
into
PERFUM
uses
the
term
"
buffer
zone"
which
equates
to
the
distance
downwind
at
which
a
specific
target
concentration
(
i.
e.,
combination
of
HEC
and
UF)
is
met
based
on
the
desired
statistical
parameters.
The
use
of
this
term
does
not
imply
any
regulatory
decision.
In
the
context
of
this
risk
assessment,
it
should
only
be
considered
as
the
predicted
distance
for
a
specific
target
concentration.
A
number
of
differing
factors
were
considered
to
evaluate
the
sensitivity
of
the
results
to
changes
in
various
inputs.

Based
on
the
range
of
input
parameters
that
have
been
considered
in
this
analysis
and
the
various
outputs
that
are
available,
some
general
conclusions
can
be
drawn
with
regard
to
the
trends
observed
in
the
results
including:

°
In
many
situations,
predicted
buffer
distances
are
1440
meters
which
is
the
maximum
distance
that
the
PERFUM
model
will
predict
even
at
lower
percentiles
of
exposure
(
e.
g.,
50th).
However,
in
other
situations,
PERFUM
predicts
that
buffer
distances
can
be
in
proximity
to
the
treated
structure
or
chamber
even
at
the
highest
percentiles
of
exposure.
It
appears
that
for
the
scenarios
which
have
been
summarized
that
the
APHIS
PPQ
and
Portable
Stack
aeration
approaches
consistently
have
the
lowest
buffer
distances
associated
with
them
and
that
no­
stack
situations
tend
to
have
the
highest
buffer
distances
associated
with
them.

°
Given
all
of
the
complexity
of
the
input
values,
the
Agency
does
not
believe
that
use
of
a
particular
source
of
weather
data
(
e.
g.,
Flint
or
Tallahassee)
will
impact
the
general
trends
in
the
results.

°
The
commodity
treatment
industry
is
extremely
broad
and
it
is
clear
that
the
situations
where
methyl
bromide
is
used
vary
extensively
from
highly
sophisticated
negative
pressure
chambers
to
other
situations
as
simple
as
fumigation
of
a
Sea­
Van
or
tarped,
palletized
commodities
sitting
on
a
loading
dock.
As
such,
the
Agency
has
attempted
to
capture
the
range
in
this
assessment.
It
is
clear
that
as
several
factors
increase
that
predicted
buffer
distances
increase.
These
include:
structure
size,
application
rate,
and
percentage
aerated.
Increases
in
other
factors
are
inversely
proportional
to
buffer
distance
and
these
include
such
factors
as
exit
velocity
and
stack
height.
36
°
PERFUM
has
the
capability
of
evaluating
how
risks
(
i.
e.,
MOEs)
change
at
a
specific
location
if
different
percentiles
of
exposure
or
other
statistics
are
selected.
It
appears
that,
in
general,
risk
estimates
are
not
extremely
sensitive
to
changes
in
the
selected
percentile
at
the
upper
percentiles
of
exposure
(
e.
g.,
95th
to
99th).
This
phenomenon
appears
to
be
due
to
the
flatness
of
the
Gaussian
curve
upon
which
ISCST3
is
based
at
the
upper
percentiles
of
exposure.

It
is
clear
that
given
the
number
of
possible
permutations
of
PERFUM
inputs
and
ways
of
presenting
the
outputs
that
there
are
many
possible
approaches
for
interpreting
the
results.
The
central
goal,
however,
is
to
quantify
how
potential
risks
change
with
changes
in
various
input
factors.
Each
of
these
factors
have
been
considered
and
very
detailed
results
pertaining
to
each
are
available
in
the
appendices
referenced
above.
In
order
to
summarize
the
analyses
which
have
been
completed
and
to
illustrate
the
general
approach,
a
selected
number
of
tabular
and
graphical
interpretations
of
the
results
are
presented
below.
In
the
examples
below,
the
basic
trends
have
been
illustrated
using
results
for
the
4
hour
duration
and
4
lb
methyl
bromide/
1000
cubic
feet
scenarios
because
the
application
rate
is
at
or
slightly
above
the
maximum
application
rate
for
most
commodities
with
a
food
tolerance
and
use
of
the
4
hour
duration
(
i.
e.,
1
hour
emission
and
3
hours
no­
emissions
to
calculate
a
time
weighted
average)
provides
the
closest
comparison
to
the
8
hour
HEC
(
30
ppm)
which
is
the
hazard
basis
for
these
calculations.
[
Note:
The
results
in
this
category
are
contained
in
Appendix
F4
as
described
above.]
In
addition
to
the
basic
trends
it
is
also
important
to
illustrate
how
inputs
such
as
uncertainty
factor,
duration
of
exposure,
and
application
rate
can
also
impact
results.

An
important
premise
for
evaluating
commodity
treatments
is
that
the
concept
is
simplistic
in
that
the
objective
is
to
place
a
commodity
in
a
room
or
chamber,
apply
methyl
bromide
to
it
at
a
specific
air
concentration
for
a
specific
time
during
which
the
goal
is
to
retain
methyl
bromide
so
it
can
be
efficacious.
Once
a
treatment
duration
is
complete
the
goal
is
to
aerate
methyl
bromide
from
the
room
or
chamber
as
quickly
as
possible.
During
treatment,
it
is
a
given
that
chambers
leak
to
some
extent
or
another
unless
the
chamber
is
extremely
well
engineered,
maintained,
and
the
operators
are
highly
trained
and
experienced.
The
amount
of
leakage
during
treatment
can
be
very
low
but
it
still
likely
occurs
even
in
the
best
situations
(
e.
g.,
1
to
10%
of
the
treatment
amount).
Conversely,
in
the
worst
situations,
leakage
during
treatment
can
be
very
high
(
e.
g.,
10
to
50%).
The
Agency
has
considered
this
in
these
results.
After
treatments
are
complete
the
objective
is
to
aerate
as
quickly
as
possible
but
the
mass
being
aerated
depends
upon
how
well
the
chamber
worked
at
retaining
methyl
bromide.
Again,
there
is
a
range
where
the
best
chambers
can
likely
retain
99
percent
or
so
of
the
administered
methyl
bromide
but
more
typically
it
would
be
expected
that
between
75
and
95
percent
or
so
of
the
administered
may
be
available
at
the
beginning
of
aeration.
These
ranges
have
all
been
considered
in
the
assessment.
Figures
6,
7,
8,
and
9
below
illustrate
how
changes
in
aeration
type
can
vary
based
on
the
nature
of
the
aeration
practice
(
i.
e.,
all
are
PERFUM
maximum
buffer
results
for
illustrative
purposes).
Figure
6
presents
the
results
for
a
minimum
stack
scenario
using
chambers
from
1000
to
100,000
cubic
feet
and
an
air
exchange
rate
of
0.05X/
minute.
Figure
7
is
similar
except
the
air
exchange
has
been
increased
to
the
APHIS
PPQ
standard
of
1
air
exchange/
minute.
Figure
8
presents
results
for
a
no­
stack
scenario
which
essentially
represents
what
would
happen
if
a
chamber
was
treated
and
aeration
occurred
by
opening
a
door.
Figure
9
presents
the
results
for
the
APHIS
PPQ
standard
method
of
an
air
exchange
per
minute
using
ground­
level
portable
output
vents
in
secured
areas
near
a
chamber
(
e.
g.,
parking
lot).
APHIS
PPQ
use
of
a
portable
50
tall
stack
was
also
evaluated
but
all
analyses
resulted
in
a
0
meter
buffer
distance
prediction.
Figure
10
illustrates
how
whole­
field
results
may
differ
from
the
maximum
buffer
distances
using
the
no
stack
scenario
for
comparison
(
i.
e.,
compare
to
Figure
8).
37
0
200
400
600
800
1000
1200
1400
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
97
99
99.9
99.99
Percentile
of
Exposure
Buffer
Distance
(
meters)
1Kcft95%

1Kcft75%

10Kcft95%

10Kcft75%

50Kcft95%

50Kcft75%

100Kcft95%

100Kcft75%

Figure
6:
Methyl
Bromide
Maximum
Distance
Buffers
Based
On
UF30,
Ventura
Weather,
4
hour
Duration,
4
lb/
1000
cu.
ft.,
Minimum
Stack
Aeration
(
0.05
exch/
min.)
­
75
&
95%
Mass
Release
0
100
200
300
400
500
600
700
800
5
15
25
35
45
55
65
75
85
95
99
99.99
Percentile
of
Exposure
Buffer
Distance
(
meters)
1Kcft95%

1Kcft75%

10Kcft95%

10Kcft75%

50Kcft95%

50Kcft75%

100Kcft95%

100Kcft75%

Figure
7:
Methyl
Bromide
Maximum
Distance
Buffers
Based
On
UF
30,
Ventura
Weather,
4
hour
Duration,
4
lb/
1000
cu.
ft,
Minimum
Stack
Aeration
(
1
exch/
min.)
­
75
&
95%
Mass
Release
0
200
400
600
800
1000
1200
1400
1600
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
97
99
99.9
99.99
Percentile
of
Exposure
Buffer
Distance
(
meters)
1Kcft95%

1Kcft75%

10Kcft95%

10Kcft75%

50Kcft95%

50Kcft75%

100Kcft95%

100Kcft75%

Figure
8:
Methyl
Bromide
Maximum
Distance
Buffers
Based
On
UF30,
Ventura
Weather,
4
hour
Duration,
4
lb/
1000
cu.
ft,
No
Stack
Aeration
­
75
&
95%
Mass
Release
38
0
5
10
15
20
25
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
97
99
99.9
99.
99
Percentile
of
Exposure
Buffer
Distance
(
meters)
1Kcft95%

1Kcft75%

10Kcft95%

10Kcft75%

50Kcft95%

50Kcft75%

100Kcft95%

100Kcft75%

Figure
9:
Methyl
Bromide
Maximum
Distance
Buffers
Based
On
UF
30,
Ventura
Weather,
4
hour
Duration,
4
lb/
1000
cu.
ft,
PPQ
Aeration
(
1
air
exch./
min.)
­
75
&
95%
Mass
Release
0
200
400
600
800
1000
1200
1400
1600
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
97
99
99.9
99.99
Percentile
of
Exposure
Buffer
Distance
(
meters)
1Kcft95%

1Kcft75%

10Kcft95%

10Kcft75%

50Kcft95%

50Kcft75%

100Kcft95%

100Kcft75%

Figure
10:
Methyl
Bromide
Whole
Field
Buffer
Distances
Based
On
UF30,
Ventura
Weather,
4
hour
Duration,
4
lb/
1000
cu.
ft,
No
Stack
Aeration
­
75
&
95%
Mass
Release
The
results
presented
in
Figures
6
through
10
indicate
that
except
for
the
PPQ
and
portable
stack
aeration
procedures
that
at
higher
percentiles
of
exposure
100
meters
or
more
buffer
distance
is
required
even
for
smaller
chambers
such
as
10,000
cubic
feet
(
i.
e.,
a
room
approximately
40x25x10
feet).
In
some
cases,
the
smaller
1000
cubic
feet
chambers
require
much
less
buffer
distance.
In
many
cases
such
as
larger
chambers
and
the
highest
percentiles,
predicted
buffer
distances
exceed
1000
meters
and
even
achieve
the
maximum
PERFUM
distance
of
1440
meters.
Based
on
stakeholder
inputs,
buffer
distances
of
100+
meters
would
require
substantial
operational
changes
in
order
to
be
compliant
in
many
situations
because
of
the
physical
layout,
surrounding
properties,
and
topography
of
many
use
sites.
For
larger
chambers
at
the
highest
percentiles,
consideration
of
either
whole
or
maximum
buffer
results
has
little
or
no
impact
because
of
the
typical
operational
constraints
of
many
users.
Table
7
below
provides
a
summary
of
some
of
the
values
included
in
Figures
6
through
10
for
illustrative
purposes.
[
Note:
Refer
to
Appendix
F4
and
Appendix
F5,
Tables
16
through
20
for
more
information.]
39
Table
7:
PERFUM
Methyl
Bromide
Buffer
Distances
(
meters)
For
All
Aeration
Processes
Considered
Based
On
UF30,
4
hour
Exposure
Duration,
4
lb/
1000
cubic
feet
Application
Rate,
Varied
Structure
Size
&
Varied
Percent
Mass
Released
Aeration
Type
Percentile
1000
Cubic
Feet
10000
Cubic
Feet
50000
Cubic
Feet
100000
Cubic
Feet
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
Maximum
Buffer
Distances.

Minimum
Stack
0.05
xch/
min
95
10
0
130
90
580
460
895
710
99
15
10
155
110
680
540
1065
855
99.9
20
15
185
140
705
560
1145
920
Minimum
Stack
1
xch/
min
95
0
0
70
60
115
85
235
160
99
0
0
85
70
135
105
445
325
99.9
10
0
110
90
145
115
695
530
No
Stack
95
65
55
335
285
875
755
1380
1180
99
75
60
370
320
995
855
1440
1340
99.9
80
65
385
335
1030
890
1440
1385
Portable
Stack
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
0
0
0
0
0
0
99.9
0
0
0
0
0
0
0
0
PPQ
1
xch/
min.
95
5
0
0
0
0
0
0
0
99
10
5
0
0
0
0
0
0
99.9
10
5
15
0
0
0
0
0
Whole
Field
Buffer
Distances.

Minimum
Stack
0.05
xch/
min
95
0
0
0
0
40
35
0
0
99
0
0
50
40
200
160
280
230
99.9
10
0
120
85
535
425
850
675
Minimum
Stack
1
xch/
min
95
0
0
0
0
0
0
0
0
99
0
0
20
0
45
40
105
90
99.9
0
0
65
50
105
80
220
155
No
Stack
95
0
0
15
10
35
35
40
35
99
20
15
115
95
295
260
440
385
99.9
60
50
320
270
835
720
1440
1125
Portable
Stack
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
0
0
0
0
0
0
99.9
0
0
0
0
0
0
0
0
Table
7:
PERFUM
Methyl
Bromide
Buffer
Distances
(
meters)
For
All
Aeration
Processes
Considered
Based
On
UF30,
4
hour
Exposure
Duration,
4
lb/
1000
cubic
feet
Application
Rate,
Varied
Structure
Size
&
Varied
Percent
Mass
Released
Aeration
Type
Percentile
1000
Cubic
Feet
10000
Cubic
Feet
50000
Cubic
Feet
100000
Cubic
Feet
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
95%
Mass
Release
75%
Mass
Release
40
PPQ
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
0
0
0
0
0
0
99.9
0
0
0
0
0
0
0
0
In
addition
to
concerns
over
appropriate
buffer
distances
and
other
mitigation
strategies
during
the
aeration
phase
of
methyl
bromide
use
in
commodity
treatments,
it
is
also
important
to
consider
how
much
material
may
leak
from
a
chamber
during
the
treatment
phase
(
Table
8).
In
order
to
simulate
this,
low
percentage
mass
release
values
were
used
to
mimic
such
situations.
These
estimates
were
calculated
based
on
all
aeration
types
but
it
is
believed
that
the
no­
stack
scenario
best
represents
real­
world
conditions
because
of
a
lack
of
active
aeration
(
i.
e.,
no
fans
are
used
to
push
methyl
bromide
from
the
chamber
in
the
no­
stack
aeration,
it
essentially
represents
a
leaky
box
which
is
what
would
be
expected
during
treatment
in
most
situations).
It
is
clear
that
based
on
the
results
presented
in
Table
8
that
in
most
circumstances
some
sort
of
buffer
distance
or
other
mitigation
option
(
e.
g.,
a
performance
criteria
for
leaking
less
than
a
specific
percentage
of
the
applied
mass)
needs
to
be
in
place
to
reduce
exposures
for
those
in
proximity
to
a
structure
during
treatment
itself
except
for
the
smallest
chambers
considered.

Table
8:
PERFUM
Methyl
Bromide
Buffer
Distances
(
meters)
During
Treatment
Based
On
UF30,
4
hour
Exposure
Duration,
4
lb/
1000
cubic
feet
Application
Rate,
Varied
Structure
Size
&
Varied
Percent
Mass
Released
Aeration
Type
Percentile
1000
Cubic
Feet
10000
Cubic
Feet
50000
Cubic
Feet
100000
Cubic
Feet
10%
Mass
Release
1%
Mass
Release
10%
Mass
Release
1%
Mass
Release
10%
Mass
Release
1%
Mass
Release
10%
Mass
Release
1%
Mass
Release
Maximum
Buffer
Distances.

No
Stack
95
0
0
60
0
205
0
335
35
99
0
0
75
0
230
0
375
45
99.9
0
0
80
0
240
0
390
50
Whole
Field
Buffer
Distances.

No
Stack
95
0
0
0
0
10
0
20
0
99
0
0
15
0
75
0
120
0
99.9
0
0
55
0
195
0
320
30
Along
with
the
factors
examined
above,
the
Agency
also
investigated
the
impact
varying
both
the
duration
of
exposure
in
order
to
more
closely
mimic
real­
world
conditions
(
i.
e.,
1
hour
durations)
and
also
to
present
more
realistic
risk
estimates
(
i.
e.,
4
hour
durations).
The
1
hour
duration
exposure
intervals
are
as
close
as
the
PERFUM
model
can
represent
many
commodity
treatment
situations
where
aeration
is
rapidly
completed.
The
issue
is,
however,
that
albeit
a
better
simulation
of
many
actual
exposure
events
the
1
hour
duration
does
not
provide
a
more
realistic
risk
estimate
because
the
HEC
41
0
200
400
600
800
1000
1200
1400
1600
1hr1lbmax
1hr4lbmax
4hr1lbmax
4hr4lbmax
1hr1lbw
f
ld
1hr4lbw
f
ld
4hr1lbw
f
ld
4hr4lbw
f
ld
Duration/
Rate/
Type
Buffer
Distance
(
m)

10Kcuf
t/
95th%

100Kcuft/
95th%

10Kcuf
t/
99.9th%

100Kcuft/
99.9th%

Figure
11:
Methyl
Bromide
Minimum
Stack
(
0.05
xch/
min.)
95th
&
99.9th
Percentile
Buffer
Distances
Based
On
UF30,
&
Varied
Structure
Size,
Duration,
Application
Rate
used
to
calculate
risks
is
based
on
a
8
hour
exposure
interval.
The
available
hazard
data
do
not
allow
for
a
more
refined
HEC
estimate.
In
order
to
better
approximate
likely
risks
4
hour
exposure
durations
were
also
considered
which
were
calculated
by
including
1
hour
of
emission
coupled
with
3
hours
of
no
emissions.
This
approach
more
closely
approximates
the
8
hour
HEC,
which
is
based
on
continuous
exposure
over
that
time,
but
the
comparison
is
still
somewhat
conservative.
[
Note:
In
some
ports
and
other
treatment
facilities,
the
frequency
of
treatments,
or
number
of
batches
treated
on
a
daily
basis
is
high.
In
order
to
address
these
types
of
occurrences,
the
Agency
completed
PERFUM
calculations
using
a
4
hour
­
4
event
scenario.
However,
these
calculations
have
not
been
summarized
for
the
purposes
of
this
assessment
to
save
resources
because
any
likely
mitigation
strategy
based
on
a
single
event
would
also
impact
these
estimates.
The
PERFUM
outputs
can
be
provided
to
interested
parties
for
examination
is
so
desired.]
Application
rate
is
also
a
key
factor
in
determining
buffer
distances
using
the
PERFUM
approach.
All
of
the
summaries
presented
above
are
based
on
an
application
rate
of
4
lb/
1000
cubic
feet
which
is
the
maximum
rate
or
just
slightly
above
(
i.
e.,
it
is
3.5
lb/
1000
cubic
feet
for
many
crops)
for
most
commodities
that
have
an
associated
food
tolerance.
It
has
also
been
noted
by
many
stakeholders
that
a
significant
portion
of
methyl
bromide
applications
do
not
occur
at
that
rate
but
occur
at
much
lower
rates.
In
order
to
examine
the
effect
of
lowering
the
application
rate
a
value
of
1lb/
1000
cubic
feet
was
also
used
to
illustrate
a
more
typical
use
situation.
Figures
11,
12,
13,
and
14
below
illustrate
how
changes
in
exposure
duration
and
application
rates
can
impact
predicted
buffer
distances.
Figure
11
presents
the
results
for
a
minimum
stack
scenario
using
10,000
and
100,000
cubic
feet
chambers
and
an
air
exchange
rate
of
0.05X/
minute.
Figure
12
is
similar
except
the
air
exchange
has
been
increased
to
the
APHIS
PPQ
standard
of
1
air
exchange/
minute.
Figure
13
presents
results
for
a
no­
stack
scenario
which
essentially
represents
what
would
happen
if
a
chamber
was
treated
and
aeration
occurred
by
opening
a
door.
Figure
14
presents
the
results
for
the
APHIS
PPQ
standard
method
of
an
air
exchange
per
minute
using
groundlevel
portable
output
vents
in
secured
areas
near
a
chamber
(
e.
g.,
parking
lot).
APHIS
PPQ
use
of
a
portable
50
tall
stack
was
also
evaluated
but
all
analyses
resulted
in
a
0
meter
buffer
distance
prediction.
42
0
200
400
600
800
1000
1200
1400
1600
1hr1lbmax
1hr4lbmax
4hr1lbmax
4hr4lbmax
1hr1lbwf
ld
1hr4lbwf
ld
4hr1lbwf
ld
4hr4lbwf
ld
Duration/
Rate/
Type
Buffer
Distance
(
m)

10Kcuf
t/
95th%

100Kcuft/
95th%

10Kcuf
t/
99.9th%

100Kcuft/
99.9th%

Figure
12:
Methyl
Bromide
Minimum
Stack
(
1
xch/
min.)
95th
&
99.9th
Percentile
Buffer
Distances
Based
On
UF
30
&
Varied
Structure
Size,
Duration,
Application
Rate
0
200
400
600
800
1000
1200
1400
1600
1hr1lbmax
1hr4lbmax
4hr1lbmax
4hr4lbmax
1hr1lbw
f
ld
1hr4lbw
f
ld
4hr1lbw
f
ld
4hr4lbw
f
ld
Duration/
Rate
/
Type
Buffer
Distance
(
m)

10Kcuf
t/
95th%

100Kcuf
t/
95th%

10Kcuf
t/
99.9th%

100Kcuf
t/
99.9th%

Figure
13:
Methyl
Bromide
No
Stack
Aeration
95th
&
99.9th
Percentile
Buffer
Distances
Based
On
UF
30
&
Varied
Structure
Size,
Duration,
Application
Rate
0
200
400
600
800
1000
1200
1400
1600
1hr
1lbmax
1hr4lbmax
4hr
1lbmax
4hr4lbmax
1hr
1lbwf
ld
1hr
4lbwf
ld
4hr
1lbwf
ld
4hr
4lbwf
ld
Duration/
Rate/
Type
Buffer
Distance
(
m)

10Kcuft/
95th%

100Kcuft/
95th%

10Kcuft/
99.9th%

100Kcuft/
99.9th%

Figure
14:
Methyl
Bromide
PPQ
Aeration
(
1
xch/
min.)
95th
&
99.9th
Percentile
Buffer
Distances
Based
On
UF
30
&
Varied
Structure
Size,
Duration,
Application
Rate
43
The
results
presented
in
Figures
11
through
14
indicate
that
the
PPQ
and
portable
stack
aeration
procedures
as
well
as
the
minimum
stack
at
full
exit
velocity
have
smaller
associated
buffer
distances.
For
larger
structures
at
lower
aeration
velocities,
predicted
buffer
distances
are
large
and
likely
will
result
in
operational
changes
by
users
regardless
of
whether
1
or
4
hour
durations
are
considered
or
even
based
on
application
rate.
It
is
also
clear
from
Figures
11
through
14
that
lower
application
rates
have
lower
associated
buffer
distances
as
would
be
expected.
It
is
also
clear
that
the
longer
the
averaging
time
for
a
single
exposure
event
the
lower
the
associated
buffer
distances
as
also
would
be
expected.
The
Agency
reaffirms
that
the
4
hour
duration
results
probably
represent
the
most
refined
risk
estimates
because
they
result
in
a
closer
comparison
to
the
8
hour
HEC.
The
values
presented
in
Figures
11
through
14
above
represent
the
losses
that
would
be
expected
during
aeration
after
treatment.
PERFUM
outputs
were
also
summarized
to
examine
similar
results
during
treatment
(
i.
e.,
at
1
and
10
percent
applied
mass
loss
as
above).
The
trends
were
similar
for
those
observed
above
in
Table
8
where
predicted
buffer
distances
were
much
lower
as
expected
and
the
general
relationship
between
exposure
duration
and
application
rate
with
predicted
buffer
distances
also
still
applies.
Table
9
below
provides
a
summary
of
some
of
the
values
included
in
Figures
11
through
14
for
illustrative
purposes.
[
Note:
Refer
to
Appendix
F5,
Tables
21
through
28
for
more
information.]

Table
9:
PERFUM
Methyl
Bromide
Buffer
Distances
(
meters)
For
All
Aeration
Processes
Considered
Based
On
UF30,
95%
Applied
Mass
Release,
&
Varied
Structure
Size,
Exposure
Duration,
Application
Rate
Aeration
Type
Percentile
1
Hour
&
1
lb/
1000
cu.
ft
1
Hour
&
4
lb/
1000
cu.
ft
4
Hour
&
1
lb/
1000
cu.
ft
4
Hour
&
4
lb/
1000
cu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
Maximum
Buffer
Distances.

Minimum
Stack
0.05
xch/
min
95
100
790
480
1440
25
165
130
895
99
120
860
515
1440
30
215
155
1065
99.9
135
965
560
1440
35
275
185
1145
Minimum
Stack
1
xch/
min
95
70
225
245
1440
0
55
70
235
99
85
360
340
1440
25
75
85
445
99.9
95
500
370
1440
30
140
110
695
No
Stack
95
305
1270
710
1440
135
570
335
1380
99
320
1340
750
1440
150
645
370
1440
99.9
330
1365
765
1440
155
670
385
1440
Portable
Stack
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
0
0
0
0
0
0
99.9
0
0
0
0
0
0
0
0
PPQ
1
xch/
min.
95
0
0
85
385
0
0
0
0
99
0
0
90
1005
0
0
0
0
99.9
0
0
95
1440
0
0
0
0
Table
9:
PERFUM
Methyl
Bromide
Buffer
Distances
(
meters)
For
All
Aeration
Processes
Considered
Based
On
UF30,
95%
Applied
Mass
Release,
&
Varied
Structure
Size,
Exposure
Duration,
Application
Rate
Aeration
Type
Percentile
1
Hour
&
1
lb/
1000
cu.
ft
1
Hour
&
4
lb/
1000
cu.
ft
4
Hour
&
1
lb/
1000
cu.
ft
4
Hour
&
4
lb/
1000
cu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
10K
cu.
ft
100Kcu.
ft
44
Whole
Field
Buffer
Distances.

Minimum
Stack
0.05
xch/
min
95
0
70
45
165
0
0
0
0
99
60
315
230
1105
0
80
50
280
99.9
95
730
470
1440
25
155
120
850
Minimum
Stack
1
xch/
min
95
0
0
0
40
0
0
0
0
99
25
125
95
460
0
0
20
105
99.9
70
220
215
1440
0
55
65
220
No
Stack
95
25
85
45
145
0
25
15
40
99
145
585
345
1330
45
200
115
440
99.9
295
1285
695
1440
125
545
320
1440
Portable
Stack
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
0
0
0
0
0
0
99.9
0
0
0
0
0
0
0
0
PPQ
1
xch/
min.
95
0
0
0
0
0
0
0
0
99
0
0
50
0
0
0
0
0
99.9
0
0
80
1440
0
0
0
0
An
issue
that
has
been
recurrent
throughout
the
development
of
this
and
other
similar
fumigant
risk
assessments
is
the
reliability
of
predicted
buffer
zones.
Often,
this
has
been
examined
by
ascertaining
what
risks
for
an
individual
might
be
if
they
happened
to
have
an
excursion
within
an
established
buffer
distance.
This
situation,
by
definition,
would
represent
an
individual
in
a
situation
where
the
Agency's
level
of
concern
would
be
exceeded.
In
order
to
examine
the
relative
change
in
buffer
distance
with
changing
uncertainty
factor
(
i.
e.,
MOE
change
with
distance)
an
analysis
was
completed
using
no
stack
aeration
maximum
buffer
distances,
75
and
95
percent
mass
releases,
4
hour
duration,
4
lb/
1000
cubic
feet
application
rate,
and
a
100000
cubic
feet
chamber
(
Figure
15).
As
expected,
as
the
target
uncertainty
factors
decrease
the
predicted
buffer
distances
also
decreased.
At
an
MOE
or
UF
=
1
(
i.
e.,
the
NOAEL
HEC)
predicted
buffers
are
<
200
meters
and
at
a
UF
=
3
predicted
buffers
<
400
meters
even
at
the
highest
percentiles
of
exposure.
At
the
uncertainty
factor
=
30
buffer
distances
are
1440
meters
at
the
highest
percentiles
of
exposure.
All
totaled
it
appears
that
the
relative
change
in
distance
with
changing
uncertainty
factors
is
best
represented
by
what
could
be
described
as
a
gradual
slope
which
indicates
that
even
if
an
individual
had
an
excursion
event
within
an
established
buffer
zone
that
their
associated
risks
would
not
change
dramatically
with
that
event.
45
0
200
400
600
800
1000
1200
1400
1600
1
3
10
30
Margins
Of
Exposure
(
UF)
Buffer
Distance
(
meters)
95%
Rel./
95th
95%
Rel./
99.9th
75%
Rel./
95th
75%
Rel./
99.9th
Figure
15:
Methyl
Bromide
Buffer
Distances
At
Varied
Uncertainty
Factors
Based
On
No
Stack
Aeration,
100K
cubic
feet
Structure,
4
hour
Exposure
Duration,
4
lb/
1000
cubic
feet
Application
Rate,
&
Varied
Mass
Releases
In
conclusion,
it
is
clear
that
many
different
factors
can
impact
the
air
concentrations
(
and
hence,
risks)
in
proximity
to
structures
and
chambers
that
are
used
for
commodity
treatments
with
methyl
bromide;
these
include
many
of
the
factors
which
have
been
investigated
in
this
analysis.
It
is
also
important
to
acknowledge
this
issue
so
that
stakeholders
understand
that
the
results
of
this
analysis
can
be
interpreted
in
many
ways
depending
upon
the
factors
which
are
considered.
Many
conclusions
can
be
drawn,
but
the
key
ones
include:
(
1)
depending
upon
the
scenario
and
inputs
predicted
buffer
distances
can
range
from
adjacent
to
treatment
structures
to
distances
as
far
as
1440
meters,
it
appears
that
no­
stack
aeration
results
in
the
longest
buffer
distances
while
the
APHIS
PPQ
methods
result
in
the
shortest
general
buffer
distances,
when
stacks
are
used
greater
exit
velocities
seem
to
decrease
buffer
distances;
(
2)
the
sensitivity
of
results
to
changes
in
key
factors
is
generally
well
within
an
order
of
magnitude
for
the
factors
which
have
been
evaluated;
(
3)
PERFUM
is
an
empirically
based
approach
so
the
generation
of
use,
emissions,
facility/
structure
and
meteorological
data
would
allow
a
broader
analysis
that
could
be
applied
more
specifically
to
other
situations
across
the
country;
and
(
4)
the
identification
of
a
result,
per
se,
for
any
sort
of
regulatory
action
would
depend
upon
careful
consideration
of
the
variability
and
uncertainty
as
well
as
any
particular
merits
of
the
inputs
associated
with
each.

6.1.2
Ambient
Bystander
Exposure
From
Multiple
Regional
Sources
Ambient
levels
of
methyl
bromide
are
generally
not
attributable
to
specific
application
events,
rather
contributions
may
occur
from
multiple
sources
within
a
region.
For
example,
it
is
likely
that
individuals
could
potentially
be
exposed
to
methyl
bromide
if
they
live
in
proximity
to
or
otherwise
frequent
areas
where
significant
uses
occur
such
as
a
neighborhood
located
around
a
port
facility
during
the
season
of
use.

Exposures
from
ambient
air
that
occur
from
non­
point
sources
of
methyl
bromide
were
estimated
from
monitoring
data
collected
to
represent
conditions
at
a
regional
level.
CARB
generated
most
of
the
data
considered
in
this
analysis.
CARB
is
a
widely
recognized
institution
for
these
types
of
programs
and
it
is
46
part
of
the
California
Environmental
Protection
Agency.
CARB
conducts
air
monitoring
studies
for
various
types
of
chemicals
throughout
California.
The
studies
conducted
by
CARB
can
generally
be
categorized
as
one
of
two
types
including:
(
1)
targeted
monitoring
typically
completed
upon
request
to
provide
information
related
to
specialized
issues
such
as
fumigant
exposures
in
areas
of
high
agricultural
use
during
the
season
of
use
(
Appendix
G);
and
(
2)
routine
monitoring
for
select
pollutants
via
established
networks
in
order
to
better
quantify
exposures
in
the
general
population
(
i.
e.,
CARB
established
its
Toxic
Air
Contaminant
monitoring
program
or
TAC
for
routinely
quantifying
toxic
chemicals
such
as
soil
fumigants
in
air
in
urban
areas).
Additional
data
were
considered
that
were
generated
by
the
Alliance
of
the
Methyl
Bromide
Industry
(
AMBI).
Review
of
the
AMBI
data
identified
quality
control
issues
in
some
sample
collection
procedures
and
for
this
reason
they
are
presented
only
for
comparative
purposes.
For
ease
and
clarity,
the
Agency
has
opted
by
convention
to
describe
the
available
ambient
bystander
data
used
in
this
assessment
as
follows:

(
1)
"
CARB
Data":
includes
targeted
monitoring
data
generated
by
both
CARB
and
AMBI
focused
on
areas
of
high
agricultural
methyl
bromide
use
in
the
season
of
use
[
Note:
Targeted
monitoring
data
are
not
specific
for
commodity
uses
but
are
the
only
such
data
available
for
this
type
of
analysis.];
and
(
2)
"
TAC
Data":
includes
data
from
CARB's
Toxic
Air
Contaminant
Network
for
Methyl
bromide
that
quantifies
background
levels
in
non­
agricultural,
urban
environments.

The
results
associated
with
the
CARB
data
are
presented
in
Section
6.1.2.1
below
while
the
results
associated
with
the
TAC
data
are
presented
in
Section
6.1.2.2.

6.1.2.1
Exposures
From
Regionally
Targeted
Non­
Point
Source
Ambient
Air
Monitoring
In
2000
and
2001,
CDPR
requested
that
CARB
conduct
a
series
of
studies
to
quantify
ambient
levels
of
methyl
bromide
(
http://
www.
cdpr.
ca.
gov/
docs/
empm/
pubs/
tac/
requests.
htm).

"
Because
most
of
California's
pesticide
applications
normally
occur
in
agricultural
areas
and
are
seasonal
in
nature,
ARB
conducts
the
monitoring
studies
to
collect
data
during
the
worst­
case
situation
­
in
the
areas
of
high
use
during
the
season
of
peak
use
­
instead
of
collecting
samples
throughout
the
State.
This
"
worst­
case"
information
can
then
be
used
to
determine
the
ambient
exposures
of
those
people
living
near
places
where
pesticides
are
used."

The
CDPR
also
requested
that
the
Alliance
of
the
methyl
bromide
Industry
(
AMBI)
conduct
monitoring
studies.

For
the
targeted
ambient
air
analysis,
HED
evaluated
different
durations
of
exposure
including
single
day
acute
exposures,
short­
and
intermediate­
term
exposures,
and
chronic
exposures
(
Table
10).
Since
samples
were
collected
3
to
4
times
per
week
from
each
station,
and
the
contribution
of
specific
applications
could
not
be
determined,
the
statistics
were
calculated
by
station
and
not
on
a
regional
basis
(
e.
g.,
county).
Risks
from
acute
exposures
were
calculated
using
the
maximum
24
hour
TWA
values
measured
at
each
station
and
comparing
them
to
the
acute
24
hour
("
agricultural")
HEC
and
not
the
8
47
hour
("
commodity")
HEC
because
these
ambient
air
results
are
all
24
hour
time­
weighted
averages.

Risks
from
short­
and
intermediate­
term
exposures
(
i.
e.,
same
HEC
and
uncertainty
factors
apply
to
both
durations)
were
calculated
using
the
mean
of
8
weekly
means
calculated
by
DPR
for
samples
taken
over
the
course
of
the
use
season
and
comparing
them
to
the
short­
and
intermediate­
term
HEC.
This
approach
was
taken
in
order
to
statistically
weigh
equally
each
week's
contribution
to
the
overall
seasonal
mean
because
of
differing
numbers
of
samples
in
some
weeks.
Concentrations
over
the
course
of
a
season
monitored
in
these
studies
did
not
vary
extensively
so
calculation
of
average
concentrations
for
shorter
durations
(
e.
g.,
4
weeks)
or
even
the
use
of
an
overall
mean
of
all
samples
would
not
expected
to
be
dramatically
different
than
estimates
used
in
this
assessment.
This
supposition
is
supported
physically
because
these
studies
spanned
high
use
seasons
in
high
use
areas
and
use
would
not
be
expected
to
dramatically
change
at
these
locations
during
use
seasons.
It
should
be
noted
that
the
statistical
summaries
of
the
available
data
were
completed
by
DPR
and
that
the
Agency
reviewed
and
concurred
with
this
approach.
There
are
many
possible
ways
to
calculate
exposure
estimates
given
the
available
data
for
completing
a
short­
and
intermediate­
term
assessment.
For
example,
a
TWA
over
an
entire
season
could
be
calculated
or
weekly
TWAs
could
be
calculated
and
then
averaged
over
a
season.
The
Agency
agrees
with
DPR's
use
of
the
mean
of
8
weekly
means
because
it
does
not
weigh
results
for
the
number
of
samples
collected
in
a
week
(
i.
e.,
most
weeks
had
4
samples
but
some
had
3)
and
it
does
not
require
a
data
filling
procedure
for
the
days
missing
each
week
(
i.
e.,
usually
Wed.,
Sat.,
and
Sun
with
most
applications
early
in
the
weekend
because
of
near
school
issues).

Chronic
exposure
estimates
were
also
calculated
using
the
targeted
non­
point
source
ambient
data.
These
calculations
should
be
considered
as
rangefinder
estimates
of
exposure
because
of
a
lack
of
monitoring
studies
specifically
designed
for
this
purpose.
Specifically,
short­
and
intermediate­
term
estimates
were
amortized
to
reflect
a
potential
for
exposure
of
180
days
out
of
each
calendar
year
in
order
to
calculate
chronic
estimates
of
exposure.
This
was
determined
based
on
the
approximate
use
patterns
for
methyl
bromide
over
a
year
in
high
use
areas.
This
approach
does
introduce
the
potential
for
significant
uncertainty
into
the
estimates,
however,
the
Agency
views
the
potential
for
chronic
exposures
in
high
use
regions
as
significant
and
has
addressed
this
scenario
in
order
to
be
health
protective.
Because
there
are
many
uncertainties
associated
with
the
approach
used
in
this
assessment
it
is
difficult
to
determine
how
these
estimates
either
over­
or
under­
predict
actual
chronic
exposures
for
those
living
in
high
use
areas.
There
are
several
factors
that
should
be
considered:

°
Monitoring
was
specifically
targeted
toward
areas
of
high
use,
this
limits
the
populations
for
which
these
types
chronic
exposure
estimates
could
be
applied
(
i.
e.,
for
those
living
in
such
regions);

°
More
refined
amortization
approaches
on
a
regional
basis
could
be
possible
with
use
data,
especially
in
California,
but
in
most
regions
such
data
are
not
available;
and
°
Targeted
monitoring
was
conducted
during
selected
seasons
of
high
use,
but
because
the
data
are
limited,
the
impacts
of
changing
conditions
(
e.
g.,
from
different
pest
pressures,
use
patterns,
or
extended
seasons)
cannot
be
quantified,
especially
for
different
regions
of
the
country
with
different
climates,
which
could
lead
to
potentially
missing
higher
end
exposures
under
some
conditions.
48
Acute
exposures
for
all
of
the
monitoring
stations
considered
(
N
=
30)
do
not
exceed
HED's
level
of
concern
(
Table
10).
Results
were
similar
for
the
8
week
TWA
exposures
(
short­
and
intermediate­
term
exposures),
none
of
the
monitoring
stations
exceed
HED's
level
of
concern,
and
in
many
cases
by
orders
of
magnitude.
These
results
should
be
considered
in
conjunction
with
the
fact
that
these
studies
were
deemed
to
be
worst­
case
situations
as
described
by
CDPR
above.
HED
calculated
chronic
exposure
based
on
CARB
data
using
a
rangefinder
approach
because
monitoring
data
specifically
meant
to
establish
chronic
exposure
levels
in
high
use
areas
were
not
available.
Based
on
this
approach,
in
some
cases,
chronic
risks
exceed
HEDs
level
of
concern
(
i.
e.,
MOEs
<
100
for
6
of
41
station­
years);
however,
HED
believes
that
these
results
do
not
pose
an
imminent
health
concern
to
the
general
public
due
to
the
nature
of
the
rangefinder
calculations
as
described
above.

CDPR
also
reached
similar
conclusions
that
risks
resulting
from
exposure
to
ambient
air
were
of
minimal
concern.

Table
10:
Results
of
2000
Through
2002
California
Ambient
Monitoring
In
High
Use
Areas
During
Season
Of
Use
CA.
County
Data
Source
Site
Dates
&
Mon.
Days
(
N)
Maximum
24
Hr.
TWAs
(
ppb)
Acute
MOE!
8
Week
TWA
(
mean
of
means)
(
ppb)
Short
and
Intermediate­
Term
MOE2
Amortized
180
days
(
ppb)
Calculated
Chronic
MOE3
Kern
CARB
ARB
7/
10­
9/
1,
2000
(
25)
0.996
10040
0.189
5291
0.09
1444
6/
30­
8/
31,
2001
0.31
32258
0.12
8333
0.06
2166
SHA
7/
10­
9/
1,
2000
(
26)
3.52
2841
0.792
1263
0.39
333
CRS
7/
10­
9/
1,
2000
(
24)
14.2
704
2.16
463
1.07
121
6/
30­
8/
31,
2001
33.50
299
2.49
402
1.23
106
MVS
7/
10­
9/
1,
2000
(
26)
0.487
20534
0.092
10870
0.05
2600
6/
30­
8/
31,
2001
0.23
43478
0.08
12500
0.04
3250
VSD
7/
10­
9/
1,
2000
(
26)
0.247
40486
0.099
10101
0.05
2600
6/
30­
8/
31,
2001
0.23
43478
0.08
12500
0.04
3250
MET
7/
10­
9/
1,
2000
(
26)
0.224
44643
0.084
11905
0.04
3250
6/
30­
8/
31,
2001
0.25
40000
0.07
14286
0.03
4333
ARV
6/
30­
8/
31,
2001
0.22
45455
0.07
14286
0.03
4333
Table
10:
Results
of
2000
Through
2002
California
Ambient
Monitoring
In
High
Use
Areas
During
Season
Of
Use
CA.
County
Data
Source
Site
Dates
&
Mon.
Days
(
N)
Maximum
24
Hr.
TWAs
(
ppb)
Acute
MOE!
8
Week
TWA
(
mean
of
means)
(
ppb)
Short
and
Intermediate­
Term
MOE2
Amortized
180
days
(
ppb)
Calculated
Chronic
MOE3
49
Ventura
AMBI
(
CDPR
Stats
Used)
SHA
8/
15­
10/
10,
2001
2.94
3401
0.50
2000
0.25
520
7/
10­
8/
31,
2002
(
31)
5.77
1733
0.58
1724
0.29
448
ABD
8/
15­
10/
10,
2001
0.44
22727
0.18
5556
0.09
1444
7/
10­
8/
31,
2002
(
30)
3.44
2907
0.76
1316
0.37
351
UWC
8/
15­
10/
10,
2001
4.35
2299
0.82
1220
0.40
325
7/
10­
8/
31,
2002
(
26)
13.17
759
2.22
450
1.09
119
PVW
8/
15­
10/
10,
2001
3.17
3155
0.56
1786
0.28
464
7/
10­
8/
31,
2002
(
32)
9.51
1052
1.62
617
0.80
163
Santa
Barbara
AMBI
(
CDPR
Stats
Used)
PLN
8/
23­
10/
9,
2001
2.69
3717
0.93
1075
0.46
283
EDW
8/
23­
10/
9,
2001
11.15
897
1.32
758
0.65
200
AGC
8/
23­
10/
9,
2001
1.16
8621
0.28
3571
0.14
929
BLO
8/
23­
10/
9,
2001
4.55
2198
0.73
1370
0.36
361
SLO
8/
23­
10/
9,
2001
1.12
8929
__
__
__
__

Monterey
CARB
SAL
9/
11­
11/
3,
2000
(
31)
7.91
1264
1.29
775
0.64
203
9/
8­
11/
7,
2001
9.25
1081
1.38
725
0.68
191
OAS
9/
11­
11/
3,
2000
(
31)
1.84
5435
0.387
2584
0.19
684
CHU
9/
11­
11/
3,
2000
(
31)
2.41
4149
0.644
1553
0.32
406
9/
8­
11/
7,
2001
1.84
5435
0.56
1786
0.28
464
LJE
9/
11­
11/
3,
2000
(
30)
24.0
417
3.79
264
1.87
70
9/
8­
11/
7,
2001
14.49
690
2.82
355
1.39
94
Table
10:
Results
of
2000
Through
2002
California
Ambient
Monitoring
In
High
Use
Areas
During
Season
Of
Use
CA.
County
Data
Source
Site
Dates
&
Mon.
Days
(
N)
Maximum
24
Hr.
TWAs
(
ppb)
Acute
MOE!
8
Week
TWA
(
mean
of
means)
(
ppb)
Short
and
Intermediate­
Term
MOE2
Amortized
180
days
(
ppb)
Calculated
Chronic
MOE3
50
AMBI
(
CDPR
Stats
Used)
BBC
9/
4­
10/
26,
2002
(
32)
6.28
1592
2.08
481
1.03
126
MAQ
9/
4­
10/
26,
2002
(
32)
4.53
2208
1.12
893
0.55
236
Santa
Cruz
CARB
PMS
9/
11­
11/
3,
2000
(
31)
30.8
325
7.68
130
3.79
34
9/
8­
11/
7,
2001
21.08
474
2.99
334
1.47
88
SES
9/
11­
11/
3,
2000
(
31)
16.4
610
2.60
385
1.28
101
9/
8­
11/
7,
2001
5.31
1883
1.22
820
0.60
217
MES
9/
8­
11/
7,
2001
36.64
273
5.51
181
2.72
48
SCF
9/
8­
11/
7,
2001
0.74
13514
Not
Sampled
__
__
__

AMBI
(
CDPR
Stats
Used)
WAT
9/
4­
10/
26,
2002
(
30)
16.38
611
3.79
264
1.87
70
FRM
9/
4­
10/
26,
2002
(
31)
14.00
714
2.62
382
1.29
101
CPW
9/
4­
10/
26,
2002
(
30)
11.12
899
2.06
485
1.02
127
SCF
9/
4­
10/
26,
2002
(
7)
0.69
14493
NA
­­
­­
­­

Background
site
sampled
only
during
2
nonconsecutive
weeks
1.
Acute
MOE
based
on
maximum
24
hr
TWAs
and
24
hour
"
agricultural"
HEC
as
durations
are
similar.
2.
Short
term
and
intermediate
term
MOE
are
based
on
8
wk.
TWA
(
i.
e.,
mean
of
weekly
means).
3.
Chronic
MOE
based
on
short­/
intermediate­
term
exposures
amortized
for
180
days
exposure
per
year.

6.1.2.2
Exposures
From
Urban
Background
Ambient
Air
Monitoring
In
2002,
CARB
added
methyl
bromide
to
its
list
of
contaminants
for
which
it
routinely
screens
in
its
TAC
program
(
see
http://
www.
cdpr.
ca.
gov/
docs/
empm/
pubs/
tac/
monitoring.
htm).
The
location
of
these
monitoring
stations,
however,
shifted
from
a
potential
"
worst­
case",
in­
season
use
situation
as
described
in
section
6.1.2.1
above
to
the
following:

"
The
ARB
has
a
network
of
stations
that
routinely
monitor
California's
air
for
a
variety
of
pollutants
such
as
ozone,
particulate
matter,
metals,
and
other
toxic
air
contaminants.
In
2002,
ARB
began
monitoring
for
two
pesticides,
Methyl
bromide
and
1,3­
dichloropropene,
every
12
days
at
approximately
20
stations
in
primarily
urban
areas
throughout
the
State."

The
following
should
also
be
considered
(
see
http://
www.
arb.
ca.
gov/
aqd/
toxics/
toxuses.
html):
51
"
The
toxics
sampling
network
was
designed
to
produce
a
statewide
annual
average
to
support
the
determination
of
a
statewide
risk
assessment.
Where
fewer
than
12
continuous
months
of
data
are
present,
we
believe
that
it
is
seldom
appropriate
to
calculate
an
annual
average.
Most
of
the
toxic
substances
show
some
seasonal
variation,
and
some
substances
differ
by
as
much
as
two
orders
of
magnitude
between
the
high
and
low
periods
of
the
year.
If
a
month's
data
are
missing,
the
calculated
average
could
be
radically
different
from
the
real
average,
the
average
that
would
have
been
calculated
had
the
missing
month's
data
been
available."

TAC
monitoring
sites
are
located
throughout
California
in
urban
environments
that
include
urban
areas
such
as
Long
Beach,
Burbank,
Los
Angeles,
Fremont,
Fresno,
San
Francisco
and
San
Jose.
[
Note:
Long
Beach
is
a
major
port
facility
that
routinely
uses
methyl
bromide
for
quarantine
treatments
of
commodities
and
other
items.
The
statistical
summaries
of
the
2002/
2003
CARB
monitoring
data
are
provided
in
Table
11.

They
were
taken
directly
from
http://
www.
arb.
ca.
gov/
adam/
toxics/
statepages/
mbrstate.
html.
Maximum
values
at
each
station
were
compared
to
acute
HECs
to
estimate
acute
MOEs.
Short­
and
intermediateterm
risks
were
estimated
by
comparing
means
to
the
short­
and
intermediate­
term
HECs.
Means
were
selected
for
this
analysis
because
they
appear
in
most
cases
to
be
heavily
influenced
by
the
typical
6
to
8
week
use
season
based
on
the
relative
contributions
of
a
relatively
small
number
of
samples
and
that
medians
for
most
stations
were
reported
as
the
level
of
detection.
Medians
from
each
location
were
used
to
calculate
chronic
MOEs.
True
chronic
exposures
(
continuous
exposures
>
6
months)
in
and
around
most
of
the
monitored
sites
probably
do
not
occur
because
the
limit
of
detection
(
½
LOD
or
0.015
ppb)
has
been
reported
as
the
median
for
approximately
75
percent
of
the
stations
for
each
year
where
there
are
data.
These
monitoring
data
indicate
that
exposure
patterns
track
with
seasonal
use;
therefore,
shorter
duration
exposures
are
more
prevalent
which
reflects
the
seasonal
use
of
most
methyl
bromide
in
California.

No
exposure
levels
reported
by
through
the
TAC
program
exceed
HED's
level
of
concern
for
any
duration
of
exposure
including
acute
(
all
MOEs
>
30),
short­,
intermediate­
term
(
all
MOEs
>
30),
or
chronic
(
all
MOEs
>
100)
exposures
in
an
urban
environment
(
Table
11).

Table
11:
Results
of
2002
&
2003
California
Ambient
Monitoring
In
Urban
Areas
Site
Year
N
Results
of
Annual
MeBr
Monitoring
(
ppb)

Maximum
Acute
MOE!
Mean
Short
and
Intermediate­
Term
MOE2
Median
Chronic
MOE3
Statewide
2002
440
0.91
10989
0.042
23810
0.015
8667
2003
503
0.90
11111
0.040
25000
0.015
8667
Azusa
2002
27
0.14
71429
0.041
24390
0.03
4333
2003
28
0.16
62500
0.036
27778
0.015
8667
Burbank
2002
30
0.14
71429
0.031
32258
0.015
8667
2003
26
0.10
100000
NR
­­
0.015
8667
Table
11:
Results
of
2002
&
2003
California
Ambient
Monitoring
In
Urban
Areas
Site
Year
N
Results
of
Annual
MeBr
Monitoring
(
ppb)

Maximum
Acute
MOE!
Mean
Short
and
Intermediate­
Term
MOE2
Median
Chronic
MOE3
52
Calexico
2002
29
0.11
90909
0.020
50000
0.015
8667
2003
30
0.33
30303
0.036
27778
0.015
8667
Chula
Vista
2002
29
0.06
166667
0.021
47619
0.015
8667
2003
28
0.05
200000
NR
­­
0.015
8667
El
Cajon
2002
28
0.06
166667
0.020
50000
0.015
8667
2003
30
0.05
200000
0.021
47619
0.015
8667
Los
Angeles
2002
21
0.14
71429
NR
­­
0.03
4333
2003
29
0.10
100000
0.032
31250
0.015
8667
Long
Beach
2002
25
0.11
90909
0.035
28571
0.015
8667
2003
27
0.13
76923
0.035
28571
0.04
3250
Riverside
2002
25
0.13
76923
NR
­­
0.015
8667
2003
30
0.10
100000
0.028
35714
0.015
8667
Simi
Valley
2002
26
0.91
10989
0.101
9901
0.05
2600
2003
31
0.90
11111
0.120
8333
0.015
8667
Bakersfield
2002
29
0.22
45455
0.058
17241
0.04
3250
2003
29
0.88
11364
0.080
12500
0.04
3250
Chico
2002
29
0.14
71429
0.026
38462
0.015
8667
2003
31
0.15
66667
0.022
45455
0.015
8667
Fremont
2002
27
0.05
200000
0.018
55556
0.015
8667
2003
30
0.11
90909
0.019
52632
0.015
8667
Fresno
2002
30
0.19
52632
0.049
20408
0.015
8667
2003
31
0.19
52632
0.055
18182
0.05
2600
Roseville
2002
29
0.11
90909
0.021
47619
0.015
8667
2003
31
0.03
333333
0.016
62500
0.015
8667
San
Francisco
2002
15
0.08
125000
NR
­­
0.015
8667
2003
31
0.015
666667
0.015
66667
0.015
8667
San
Jose
­
4th
Street
2002
8
0.09
111111
NR
­­
NR
­­

San
Jose
­
Jackson
St.
2002
6
0.05
200000
NR
­­
NR
­­

2003
31
0.23
43478
0.031
32258
0.015
8667
Stockton
2002
27
0.90
11111
0.144
6944
0.05
8667
2003
30
0.48
20833
0.088
11364
0.04
8667
Mexicali
­
Mexico
2002
19
0.10
100000
NR
­­
0.015
8667
2003
17
0.07
142857
NR
­­
0.015
8667
Table
11:
Results
of
2002
&
2003
California
Ambient
Monitoring
In
Urban
Areas
Site
Year
N
Results
of
Annual
MeBr
Monitoring
(
ppb)

Maximum
Acute
MOE!
Mean
Short
and
Intermediate­
Term
MOE2
Median
Chronic
MOE3
53
Rosarito
­
Mexico
2002
25
0.05
200000
NR
­­
0.015
8667
2003
30
0.14
71429
0.027
37037
0.015
8667
1.
Acute
MOEs
based
on
maximum
24
hr
TWAs
and
24
hour
"
agricultural"
HEC
as
durations
are
similar.
2.
Short
term
and
intermediate
term
MOE
are
based
on
the
mean
concentrations.
3.
Chronic
MOEs
are
based
on
the
median
concentration.

6.2
Bystander
Risk
Characterization
Methyl
bromide
use
to
control
pests
in
commodities
that
have
established
food
tolerances
can
take
many
forms
and
by
necessity
results
in
a
wide
array
of
use
situations.
The
situations
can
range
from
very
small,
infrequent
batch
processing
to
large
scale,
highly
regimented
processes
that
occur
on
a
routine
basis.
The
scale
and
frequency
of
such
processes
are
dictated
by
the
nature
of
the
business
of
the
users.
Smaller
scale
users
may
be
a
local
walnut
producer
in
California
while
a
large
scale
user
may
be
a
food
processor
or
the
USDA
Plant
Protection
and
Quarantine
service
at
ports
like
Long
Beach,
California;
Philadelphia,
Pennsylvania;
or
Miami,
Florida.
It
is
clear
that
along
with
this
wide
array
of
users
that
there
is
a
great
diversity
of
practices
and
equipment
currently
in
use
across
the
country.
The
objective
of
this
assessment
was
to
attempt
to
capture
some
of
this
diversity
in
the
bystander
risk
assessments
using
the
monitoring
data
and
the
PERFUM
model.
Risks
from
methyl
bromide
exposure
in
ambient
air
were
also
calculated
using
data
from
California
focused
on
agricultural
use
areas
in
the
season
of
use
and
also
from
urban
centers.
These
data
may
not
provide
the
most
precise
estimates
of
risks
related
to
the
commodity
uses
of
methyl
bromide
but
at
this
point
they
are
the
only
known
source
of
information
for
such
calculations.

In
the
initial
commodity
assessment
for
methyl
bromide
(
please
refer
to
D316326
at
www.
Regulations.
gov
under
the
methyl
bromide
docket
EPA­
HQ­
OPP­
2005­
0123
for
further
information)
the
Agency
generally
based
its
calculations
on
the
approaches
used
by
the
CADPR.
This
includes
a
tiered
approach
that
calculated
risks
based
on
monitoring
data
and
the
use
of
the
EPA's
ISCST3
model
for
predicting
downwind
air
concentrations
and
associated
risks.
The
ISCST3
method
is
deterministic
because
it
is
based
on
the
use
of
static
meteorological
conditions
over
an
entire
calculation
period
(
i.
e.,
windspeed
and
atmospheric
stability
are
constrained
which
is
unrealistic)
and
it
generally
identified
risks
of
concern.
The
Agency
also
used
the
highest
possible
emission
terms
in
the
previous
assessment
to
establish
what
possible
real­
world
high­
end
risk
situations
may
be
like
(
i.
e.,
emission
values
from
the
CADPR
permit
conditions
for
commodities
were
used).
Additional
analyses
were
not
completed
due
to
a
lack
of
adequate
use
information.
Based
upon
discussions
with
CADPR,
it
appears
that
these
emissions
estimates
were
loosely
defined
using
monitoring
data
but
they
do
establish
an
effective
range
of
inputs
for
consideration
that
represent
highly
efficient
(
i.
e.,
low
loss
rate)
chambers
through
what
could
be
categorized
as
less
than
efficient
facilities.
[
Note:
Based
on
various
information
sources,
there
are
many
possible
novel
technologies
for
scrubbing
methyl
bromide
emissions
from
effluent
streams.
However,
the
Agency
does
not
believe
such
systems
to
be
able
to
readily
implemented
on
a
wide
scale.
Definitive
emission
reduction
factors
are
also
not
available
for
such
systems
so
they
have
not
been
quantitatively
addressed
in
this
assessment.]
The
goal
of
this
current
assessment
was
to
provide
a
much
broader
characterization
of
the
risks
that
could
possibly
be
expected
with
the
breadth
of
commodity
treatment
facilities
across
the
country.
This
is
54
difficult
given
a
lack
of
use
information
for
all
possible
situations
and
the
sparse
nature
of
the
monitoring
data
that
only
provides
what
can
be
described
as
situational
snapshots
of
a
few
facilities
in
California.
After
release
of
the
previous
assessment,
the
Agency
received
a
number
of
comments
pertaining
to
the
initial
commodity
assessment
which
was
completed.
Most
of
these
revolved
around
use
practices
and
the
size
and
nature
of
the
facilities
as
well
as
the
commodities
that
were
treated.
Additionally,
the
Agency
is
continuously
seeking
additional
information
through
venues
such
as
the
methyl
bromide
alternatives
conference
(
i.
e.,
www.
MBAO.
ORG)
and
is
actively
engaged
with
USDA
and
the
Plant
Protection
and
Quarantine
Service.
With
all
of
this
newly
identified
information
the
Agency
developed
a
series
of
refined
modeling
inputs
that
are
described
above
(
Section
6.1.1.1)
in
an
attempt
to
bracket
use
situations
across
the
country.
Additionally,
monitoring
data
were
also
used
to
directly
calculate
risks
and
(
in
the
form
of
the
CADPR
permit
condition
emission
factors)
to
"
groundtruth"
the
refined
inputs.
The
new
inputs
indeed
bracket
what
is
known
from
the
monitoring
data.
However,
the
monitoring
data
are
limited
in
scope
and
the
newly
developed
inputs,
by
definition,
are
intended
to
provide
a
much
broader
consideration
of
the
industry.
It
is
difficult
to
attempt
to
overlay
how
actual
methyl
bromide
use
practices
for
commodity
treatments
overlay
with
the
grid
of
new
inputs
because,
in
general,
there
is
a
lack
of
appropriate
information
with
which
to
attempt
to
complete
such
an
effort.
For
this
reason,
the
results
of
this
assessment
should
be
considered
to
represent
general
categories
within
the
commodity
treatment
industry.
These
may
include
small,
medium,
and
large
facilities
or
facilities
with
highly
refined
use
practices
and
efficient
chambers
or
facilities
that
are
less
refined.
As
additional
use
information
becomes
available,
further
characterization
can
be
completed
and
a
more
refined
consideration
of
how
risk
estimates
may
be
applied
to
various
sectors
of
the
commodity
industry
can
be
completed.

With
regards
to
the
detailed
aspects
of
the
modeling
that
has
been
completed
for
residential
bystanders,
the
major
change
is
that
the
Agency
has
moved
from
using
the
deterministic
ISCST3
method
to
a
distributional
approach
using
PERFUM
which
has
been
recently
modified
to
consider
sources
such
as
structures
or
chambers
which
would
be
anticipated
in
commodity
treatments.
The
PERFUM
model
which
was
used
in
this
assessment
(
V2.1.2)
is
available
at
http://
www.
sciences.
com/
perfum/
index.
html.
Version
2.1.2
of
PERFUM
will
eventually
be
placed
on
the
Agency's
website
along
with
the
older
Version
1.1
http://
www.
epa.
gov/
opphed01/
models/
fumigant/.
In
previous
assessments
using
PERFUM,
multiple
sources
of
weather
information
were
used
and
in
this
case
data
from
coastal
locations
in
California
(
i.
e.,
Ventura)
and
Florida
(
i.
e.,
Tallahassee)
were
also
used
along
with
information
from
Flint
Michigan.
All
analyses
were
completed
but
only
the
Ventura
California
weather
results
were
summarized.
It
is
clear
that
so
many
factors
could
potentially
impact
buffer
distances
that
it
was
felt
this
was
sufficient.
[
Note:
The
additional
PERFUM
outputs
are
available
and
can
be
provided
upon
request.]
The
PERFUM
modeling
framework
was
subjected
to
an
SAP
review
in
2004
where
the
general
uncertainties
associated
with
its
use
were
discussed.
Please
refer
to
the
SAP
background
documents
and
the
SAP
report
for
further
information
concerning
these
issues
and
the
related
use
of
PERFUM
(
http://
www.
epa.
gov/
scipoly/
sap/
2004/
index.
htm).
One
other
consideration
is
that
PERFUM
uses
ISCST3
as
its
core
processor
as
described
above.
Recently,
the
Agency
recommended
(
40CFR51,
Appendix
W)
that
modelers
begin
to
replace
the
use
of
ISCST3
with
an
upgraded
dispersion
model
(
AERMOD).
This
recently
occurred
and
40CFR51
recommends
a
year
transition
period
between
new
and
outgoing
systems.
Additionally,
the
major
upgrade
from
ISCST3
in
AERMOD
is
that
refined
algorithms
have
been
incorporated
that
better
address
the
dispersion
of
buoyant
plumes
(
i.
e.,
heated
output
streams
which
would
naturally
rise
in
the
atmosphere
such
as
power
plant
effluents)
but
methyl
bromide
emissions
are
thought
to
be
non­
buoyant
plumes
(
i.
e.,
because
they
are
not
heated
like
a
power
plant
type
effluent).
Major
changes
in
the
algorithms
for
non­
buoyant
plumes
were
not
completed
in
55
AERMOD
so
it
is
likely
that
risks
predicted
using
either
approach
should
not
provide
significantly
different
results.
The
Agency
is
continuing
to
investigate
these
possible
differences
and
will
consider
them
when
interpreting
the
results
of
this
assessment.

Several
factors
also
need
to
be
considered
in
the
interpretation
of
the
results
associated
with
the
assessment
of
exposures
from
ambient
air.
It
is
clear
from
the
characterization
of
the
data
provided
by
CARB
and
AMBI
that
some
data
represent
highly
targeted
monitoring
in
agricultural
regions
during
the
season
of
use.
Because
of
these
criteria,
the
results
should
be
considered
conservative
in
nature
for
California
agricultural
regions.
In
addition,
CARB
has
also
developed
monitoring
data
from
its
urban
network
which
screens
not
only
for
methyl
bromide
but
for
other
pollutants
of
concern
such
as
persistent
organic
pollutants
(
POPs)
and
volatile
organic
compounds
(
VOCs).
These
data
are
intended
to
represent
urban
background
levels.
Some
of
these
stations
are
located
in
the
same
communities
where
major
commodity
fumigations
occur
(
e.
g.,
Long
Beach
CA)
which
should
be
considered
in
the
interpretation
of
the
results.
One
other
issue
that
should
be
considered
in
the
interpretation
of
the
estimates
for
ambient
air
is
that
California
has
a
number
of
restrictions
and
systems
in
place
where
the
overall
goal
is
to
reduce
environmental
emissions
from
fumigant
use.
As
such,
it
is
difficult
to
quantify
how
the
results
presented
above
may
apply
to
other
regions
of
the
country
who
do
not
have
these
types
of
programs
in
place.
In
summary,
it
is
not
clear
how
these
data
may
directly
relate
to
commodity
uses.
It
should
be
noted
that
short­
and
intermediate­
term
risks
in
general
were
well
below
any
level
of
concern
for
the
Agency.
Chronic
risks
based
on
the
urban
background
levels
were
also
well
below
any
level
of
concern.
The
only
ambient
risks
of
concern
were
for
the
chronic
estimates
that
were
calculated
using
amortized
seasonal
values
which
is
an
uncertain
process
at
best.
It
is
also
not
clear
how
the
seasonal
estimates
relate
to
commodity
uses
since
they
were
collected
in
high
agricultural
use
areas.

6.3
Residue
Profile
Sufficient
residue
chemistry
data
are
available
to
conduct
a
reasonably
reliable
dietary
exposure
assessment.
No
additional
residue
chemistry
studies
are
required,
but
the
registrants
must
modify
product
labels
so
they
are
consistent
with
the
residue
studies
(
see
40
CFR
§
180.123).

For
commodity
fumigation
uses,
residues
of
both
parent
methyl
bromide
and
inorganic
bromide
may
be
present.
HED
will
not
at
this
time
separately
assess
the
risks
resulting
from
bromide
ion
in
foods
for
the
following
reasons.
First,
parent
methyl
bromide
is
expected
to
be
more
toxic
than
bromide
ion.
Second,
since
methyl
bromide
is
metabolized
to
bromide
ion
in
mammals,
it
is
likely
that
any
toxic
effects
specific
to
the
ion
would
have
been
observed
in
the
available
animal
toxicity
studies.
Finally,
bromide
is
ubiquitous
in
the
environment.
Distinguishing
ubiquitous
levels
of
bromide
from
those
resulting
from
methyl
bromide
use
will
frequently
not
be
possible.
Therefore,
HED
recommends
that
commodity
fumigation
tolerances
for
inorganic
bromide
(
40
CFR
§
180.123)
be
revoked
and
replaced
with
tolerances
for
methyl
bromide,
per
se
(
see
D304618,
2/
8/
06,
T.
Goodlow).
3aPAD/
cPAD
=
acute/
chronic
Population
Adjusted
Dose
=
Acute
or
Chronic
RfD
FQPA
Safety
Factor
56
Enforcement
Methods.
The
head­
space
procedure
of
King
et
al.
for
determining
methyl
bromide
has
been
forwarded
to
FDA
for
inclusion
in
PAM
Vol.
II.
This
method
is
adequate
for
data
collection
and
would
be
suitable
for
tolerance
enforcement
on
plant
and
processed
food
commodities.
Analytical
methods
for
secondary
residues
of
methyl
bromide
in
livestock
commodities
are
not
required.

Multi
residue
Method.
FDA
multi
residue
test
methods
are
not
applicable
to
methyl
bromide.
Protocols
A
and
B
are
not
applicable
to
monohalogenated
alkanes.
Although
methyl
bromide
would
be
detectable
in
protocol
C,
residues
would
like
not
be
recovered
through
any
of
the
extraction
techniques.

For
more
residue
chemistry
data
considerations
and
tolerances,
please
refer
to
the
residue
chemistry
chapter.

6.4
Acute
and
Chronic
Food
Dietary
Exposure
and
Risk
Methyl
bromide
acute
and
chronic
dietary
exposure
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
software
with
the
Food
Commodity
Intake
Database
(
DEEM­
FCID
 
,
Version
2.03),
which
incorporates
consumption
data
from
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII),
1994­
1996
and
1998.
Acute
and
chronic
dietary
risks
for
methyl
bromide
resulting
from
food
intake
were
determined
for
the
general
U.
S.
population
and
various
population
subgroups.
The
partly
refined
Tier
2
acute
and
chronic
dietary
risk
assessments
were
conducted
for
all
supported
(
currently
registered
and
proposed)
methyl
bromide
food
uses.
Both
the
acute
and
chronic
dietary
exposure
assessments
for
methyl
bromide
are
based
on
anticipated
residues
derived
from
field
trial
and
USDA
monitoring
data.
Because
methyl
bromide
is
so
volatile,
HED
assumed
that
residues
in
any
food
form
that
was
heated
would
be
zero.
Use
of
minimal
aeration
time
for
methyl
bromide
treated
commodities
will
likely
overestimate
residue
levels
and
risks.

For
all
included
commodities,
the
acute
and
chronic
risks
do
not
exceed
HED's
level
of
concern
(<
100%
PAD3)
for
the
general
U.
S.
population
and
all
population
subgroups
(
Table
12).
The
acute
dietary
exposure
estimate
for
females
13­
49
years
old,
the
highest
exposed
population
subgroup
is
2.4%
of
the
aPAD.
The
chronic
dietary
exposure
estimate
for
children
(
3
to
5
years
old),
the
most
highly
exposed
subgroup
is
10%
of
the
cPAD
(
for
details,
see
dietary
assessment
D304603,
2/
21/
06).
All
dietary
exposure
estimates
are
listed
in
Table
12
below.
57
Table
12.
Summary
of
Dietary
Exposure
and
Risk
for
Methyl
Bromide
Population
Subgroup**
Acute
Dietary
(
95th%
ile)
Chronic
Dietary
aPAD
mg/
kg/
day
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
cPAD
mg./
kg/
day
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
General
U.
S.
Population
0.9
0.004169
<
1
0.022
0.000869
4.0
All
Infants
(<
1
year
old)
0.000939
<
1
0.000247
1.1
Children
1­
2
years
old
0.011300
1.3
0.002144
9.7
Children
3­
5
years
old
0.011771
1.3
0.002288
10
Children
6­
12
years
old
0.007208
<
1
0.001280
5.8
Youth
13­
19
years
old
0.003127
<
1
0.000551
2.5
Adults
20­
49
years
old
0.003253
<
1
0.000660
3.0
Females
13­
49
years
old
0.14
0.003369
2.4
0.000642
2.9
Adults
50+
years
old
0.9
0.003573
<
1
0.000812
3.7
Although
residues
of
the
bromide
ion
may
occur
in
food
as
a
result
of
Methyl
bromide
use,
these
residues
cannot
be
readily
distinguished
from
background
levels
of
bromide.
Therefore,
the
dietary
exposure
assessment
has
been
completed
only
for
Methyl
bromide,
per
se,
which
is
expected
to
be
the
predominant
contributor
to
dietary
risk.

The
values
for
the
population
with
the
highest
risk
for
each
type
of
risk
assessment
are
bolded.

6.5
Water
Exposure/
Risk
Pathway
Estimated
drinking
water
concentrations
(
EDWCs)
for
methyl
bromide
were
modeled
using
PRZMEXAMS
for
surface
water.
Florida
strawberry
field
use
resulted
in
the
highest
surface
water
concentration
of
357
µ
g/
L
for
use
in
acute
assessments
and
1.0
µ
g/
L
for
chronic
assessment.
Groundwater
concentration
was
not
estimated
for
methyl
bromide
because
the
model
used
for
estimating
groundwater
concentration,
SCIGROW,
has
limited
capability
to
model
vapor
phase
transport
of
methyl
bromide
to
groundwater.
Based
on
the
data
base
of
pesticides
in
groundwater
(
U.
S.
EPA,
1992),
2
wells
in
California
(
out
of
20,429
wells
monitored
in
Florida,
California,
and
Hawaii)
had
methyl
bromide
levels
from
2.5
­
6.4
µ
g/
L.
The
maximum
concentration
for
ground
water
is
used
for
both
acute
and
chronic
assessments.
Values
are
reported
in
Table
13
below.

Table
13.
Estimated
and
monitoring
data
for
MeBr
and
bromide
ion
in
surface
water
and
groundwater
Chemical
Surface
Water
(
µ
g/
L)
Groundwater
(
µ
g/
L)
Acute
Cancer/
chronic
MeBr
357a
1.0a
6.4b
a
Based
on
1­
in­
10
year
exceedance
probability
(
0.10).
Values
reflect
output
from
PRZM/
EXAMS
multiplied
by
the
percent
crop
area
applied
(
0.87)
for
Florida
Strawberry
scenario.
b
Recommended
estimated
drinking
water
concentrations
(
EDWCs)
values
for
acute
and
chronic
for
groundwater
(
monitoring
data)
Table
13.
Estimated
and
monitoring
data
for
MeBr
and
bromide
ion
in
surface
water
and
groundwater
Chemical
Surface
Water
(
µ
g/
L)
Groundwater
(
µ
g/
L)
Acute
Cancer/
chronic
58
7.0
Aggregate
Risk
Assessment
Acute
and
chronic
dietary
risk
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
(
DEEM­
FCID
 
,
Version
2.03),
which
uses
food
consumption
data
from
the
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII)
from
1994­
1996
and
1998.
The
aggregate
assessments
consider
exposure
from
both
food
and
drinking
water
(
see
section
7.1
below).
HED
did
not
estimate
aggregate
risks
for
short­
and
intermediate­
term
exposures
because
of
the
way
bystander
exposures
have
been
estimated
in
this
assessment.
The
results
for
these
assessments,
presented
above,
represent
risks
at
various
distances
downwind
from
treated
areas
(
e.
g.,
farm
fields)
or
from
highly
targeted
ambient
air
monitoring
studies.
Since
buffer
zone
distances
or
other
mitigation
approaches
are
still
undefined,
the
appropriate
bystander
exposure
estimates
for
aggregating
with
food
and
water
have
not
yet
been
determined.

7.1
Acute
and
Chronic
Aggregate
Risk
Assessments
Acute
and
chronic
aggregate
risks
for
methyl
bromide
resulting
from
food
and
water
were
determined
for
the
general
U.
S.
population
and
various
population
subgroups.
Food
exposures
and
either
EDWCs
from
modeled
values
for
surface
water
sources
or
groundwater
sources
as
the
drinking
water
source
were
included.
Analyses
were
conducted
for
all
supported
(
currently
registered
and
proposed)
methyl
bromide
food
uses,
and
are
based
on
anticipated
residues
derived
from
field
trial
and
USDA
monitoring
data.

For
the
acute
aggregate
assessments,
females
13­
49
years
old
were
the
most
highly
exposed
subgroup.
At
the
95th
percentile
of
exposure,
the
estimated
food
and
water
exposure
for
females
13­
49
years
old
utilized
2.5%
and
13%
of
the
aPAD
for
ground
water
and
surface
water
sources,
respectively.
See
Tables
14
and
15
for
acute
aggregate
risks.

For
the
chronic
aggregate
assessments,
children
3­
5
years
old
were
the
most
highly
exposed
subgroup.
The
estimated
food
and
water
exposure
for
children
3­
5
years
old
utilized
11%
of
the
cPAD
for
both
ground
water
and
surface
water
sources.
See
Tables
14
and
15
for
chronic
aggregate
risks.

Table
14.
Summary
of
Dietary
Exposure
and
Risk
for
Methyl
Bromide
Incorporating
Surface
Water
as
a
Drinking
Water
Source
Population
Subgroup**
Acute
Dietary
(
95th%
ile)
Chronic
Dietary
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
General
U.
S.
Population
357
0.020732
2.3
1.0
0.000890
4.0
All
Infants
(<
1
year
old)
0.069891
7.8
0.000316
1.4
Table
14.
Summary
of
Dietary
Exposure
and
Risk
for
Methyl
Bromide
Incorporating
Surface
Water
as
a
Drinking
Water
Source
Population
Subgroup**
Acute
Dietary
(
95th%
ile)
Chronic
Dietary
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
59
Children
1­
2
years
old
0.034553
3.8
0.002175
9.9
Children
3­
5
years
old
0.031361
3.5
0.002317
11
Children
6­
12
years
old
0.021637
2.4
0.001300
5.9
Youth
13­
19
years
old
0.016559
1.8
0.000566
2.6
Adults
20­
49
years
old
0.018523
2.1
0.000680
3.1
Females
13­
49
years
old
0.018562
13
0.000661
3.0
Adults
50+
years
old
0.017040
1.9
0.000833
3.8
The
values
for
the
population
with
the
highest
risk
for
each
type
of
risk
assessment
are
bolded.

Table
15.
Summary
of
Dietary
Exposure
and
Risk
for
Methyl
Bromide
Incorporating
Ground
Water
as
a
Drinking
Water
Source
Population
Subgroup**
Acute
Dietary
(
95th%
ile)
Chronic
Dietary
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
aPAD
EDWC
(
µ
g/
L)
Dietary
Exposure
(
mg/
kg/
day)
%
cPAD
General
U.
S.
Population
6.4
0.004296
<
1
6.4
0.001004
4.6
All
Infants
(<
1
year
old)
0.001847
<
1
0.000689
3.1
Children
1­
2
years
old
0.011542
1.3
0.002344
11
Children
3­
5
years
old
0.012009
1.3
0.002475
11
Children
6­
12
years
old
0.007274
<
1
0.001410
6.4
Youth
13­
19
years
old
0.003292
<
1
0.000648
2.9
Adults
20­
49
years
old
0.003389
<
1
0.000786
3.6
Females
13­
49
years
old
0.003537
2.5
0.000767
3.5
Adults
50+
years
old
0.003728
<
1
0.000945
4.3
The
values
for
the
population
with
the
highest
risk
for
each
type
of
risk
assessment
are
bolded.

8.0
Cumulative
Risk
Assessment
and
Characterization
Unlike
other
pesticides
for
which
EPA
has
followed
a
cumulative
risk
approach
based
on
a
common
mechanism
of
toxicity,
EPA
has
not
made
a
common
mechanism
of
toxicity
finding
as
to
methyl
bromide
and
any
other
substances
and
methyl
bromide
does
not
appear
to
produce
a
toxic
metabolite
produced
by
other
substances.
Therefore,
for
the
purposes
of
this
tolerance
action,
EPA
has
not
assumed
that
methyl
60
bromide
has
a
common
mechanism
of
toxicity
with
other
substances.
For
information
regarding
EPA's
efforts
to
determine
which
chemicals
have
a
common
mechanism
of
toxicity
and
to
evaluate
the
cumulative
effects
of
such
chemicals,
see
the
policy
statements
released
by
EPA's
Office
of
Pesticide
Programs
concerning
common
mechanism
determinations
and
procedures
for
cumulating
effects
from
substances
found
to
have
a
common
mechanism
on
EPA's
website
at
http://
www.
epa.
gov/
pesticides/
cumulative/.

9.0
Occupational
Exposure
Data
indicate
that
worker
exposures
generally
exceed
HED's
level
of
concern
for
all
scenarios
considered
when
no
respiratory
protection
is
used.
HED
also
considered
the
use
of
either
air
purifying
respirators
(
APRs)
and
self
contained
breathing
apparatus
(
SCBA)
with
varied
results.
Generally,
the
trends
in
the
results
were
similar
for
acute
and
short­/
intermediate­
term
durations.
Chronic
exposures
were
always
of
concern
for
all
tasks
regardless
of
whether
or
not
respiratory
protection
is
used.

The
use
of
an
APR
reduces
exposure
levels
by
a
factor
of
10
and
the
use
of
SCBA
reduces
exposure
levels
by
a
factor
of
10,000.
[
Note:
There
are
commercially
available
APR
cartridges
that
have
been
evaluated
or
recommended
for
reducing
exposure
levels
of
methyl
bromide,
see
the
technical
bulletin
146
for
cartridge
60928
at
www.
3M.
com
for
more
information.]
Respirators
would
be
the
most
practical
protective
equipment
choice
for
reducing
exposures
for
most
workers.
The
use
of
SCBA
is
not
normally
deemed
to
be
a
viable
option.
It
is
not
from
a
lack
of
capability,
but
SCBA
is
too
difficult
to
handle
logistically
and
too
costly
to
implement
as
an
exposure
reduction
tool
in
most
circumstances.
However,
in
certain
situations
such
as
industrial
treatments,
HED
believes
that
SCBA
may
represent
a
viable
option
for
reducing
exposures
for
a
limited
number
of
workers.
Even
with
the
high
rate
of
protection
associated
with
these
devices,
results
were
varied
and
exposures
(
especially
of
a
chronic
nature)
were
still
of
concern
for
certain
tasks
associated
with
industrial
and
residential
settings.

The
occupational
tasks
commonly
associated
with
the
use
of
methyl
bromide
along
with
the
corresponding
risks
are
described
below
for
each
use
sector
considered
(
i.
e.,
commodity
and
industrial
uses).
[
Note:
Industrial
facility
occupational
tasks
are
included
in
this
assessment
since
they
reflect
the
types
of
jobs
that
would
be
associated
with
methyl
bromide
uses
on
commodities
in
larger
facilities
such
as
grain
and
rice
mills.]

9.1
Commodity
Fumigations
Job
tasks
that
would
be
expected
with
typical
commodity
fumigations
include:

a)
Applicator
b)
Aerator:
opens
doors
or
tarp
to
begin
aeration.
c)
Post­
Fumigation
commodity
workers
Table
16
indicates
risks
are
of
concern
for
all
scenarios
associated
with
commodity
fumigation
activities
for
all
exposure
durations
if
no
respiratory
protection
is
used
(
MOE
<
30
for
acute
&
short­/
intermediateterm
and
MOE
<
100
for
chronic).
As
a
result,
HED
evaluated
how
the
use
of
an
OVR
(
PF
10)
would
impact
worker
risks.
Risks
for
the
majority
of
commodity
fumigation
workers
who
use
the
air
purifying
respirator
(
PF
10)
still
exceed
HED's
level
of
concern;
however,
short­
and
intermediate­
term
risks
for
61
forklift
drivers
and
line
workers
who
use
the
purifying
respirator
(
PF
10)
do
not
exceed
HED's
level
of
concern
(
MOE
>
30).
Chronic
exposures
are
of
concern
(
MOE<
100)
for
all
durations
regardless
of
whether
or
not
respirators
are
used
but
the
population
of
chronically
exposed
individuals
is
expected
to
be
small
compared
to
all
handlers
of
methyl
bromide.
The
data
upon
which
this
analysis
is
based
are
presented
and
summarized
in
the
previous
assessment
for
methyl
bromide;
no
modifications
have
been
made
to
the
exposure
results
so
the
data
have
not
been
presented
herein
(
please
refer
to
D316326
at
www.
Regulations.
gov
under
the
methyl
bromide
docket
EPA­
HQ­
OPP­
2005­
0123
for
further
information;
Appendix
V:
Occupational
Risks
Associated
With
Commodity
Fumigations).

Table
16:
Commodity
MeBr
Application
Workers
Exposure
and
Risk.

Scenario
Number
of
ND
Samples
Duration
of
Maximum
Sample
Result
Sample
time
(
minutes)
Max.
Conc.
1
Monitored
PF10
Resp.
Acute
MOE
Mean
Conc.
1
Monitored
PF10
Resp.
Short­
and
Intermediateterm
MOE
Chronic
MOE
Based
On
Mean
Conc.

Commodity
Applicators
(
N=
39)
1
5
minutes
3
and
614
12
2.5
2.0
2
<
1
1.2
25
0.20
22
3
Commodity
Venting
(
n=
30)
9
5
minutes
3
and
585
33
<
1
2.3
2
<
1
3.3
9
0.23
19
2
Forklift
Driver
(
n=
27)
0
15
minutes
10
and
536
0.80
38
0.17
26
3
0.080
375
0.017
259
32
Line
Workers
(
89)
4
37
minutes
14
and
621
7.9
4
0.55
8
1
0.79
38
0.055
80
10
1.
Concentrations
are
measured
in
ppm.
For
HECs
used
to
calculated
risks
for
each
duration,
see
Table
4/
page
15.

9.2
Industrial
Fumigations
Job
tasks
that
would
be
expected
with
typical
industrial
fumigations
include:

a)
Remote
Application
b)
Canister
application
c)
Aeration
Table
17
indicates
risks
are
of
concern
for
all
scenarios
associated
with
industrial
fumigation
activities
for
all
exposure
durations
if
no
respiratory
protection
is
used
(
MOE
<
30
for
acute
&
short­/
intermediateterm
and
MOE
<
100
for
chronic).
As
a
result,
HED
evaluated
how
the
use
of
an
OVR
(
PF
10)
would
impact
worker
risks.
Additionally,
SCBA
(
PF
10,000)
were
also
considered
as
it
is
believed
that
these
represent
a
possible
risk
mitigation
measure
for
certain
workers
involved
in
industrial
fumigations.
For
remote
applicators,
only
acute
duration
risks
are
reduced
to
levels
of
no
concern
when
air
purifying
respirators
(
PF
10)
are
used;
risks
for
other
durations
still
exceed
HED's
level
of
concern.
When
SCBA
is
used
(
i.
e.,
for
canister
openers
and
venters),
acute
and
short­/
intermediate­
term
risks
are
not
of
concern
(
MOE>
30).
Chronic
exposures
are
of
concern
(
MOE<
100)
for
all
durations
regardless
of
whether
or
not
respirators
are
used
but
the
population
of
chronically
exposed
individuals
is
expected
to
be
small
compared
to
all
handlers
of
methyl
bromide.
The
data
upon
which
this
analysis
is
based
are
presented
and
summarized
in
the
previous
assessment
for
methyl
bromide;
no
modifications
have
been
made
to
the
62
exposure
results
so
the
data
have
not
been
presented
herein
(
please
refer
to
D316326
at
www.
Regulations.
gov
under
the
methyl
bromide
docket
EPA­
HQ­
OPP­
2005­
0123
for
further
information;
Appendix
W:
Occupational
Risks
Associated
With
Industrial
Fumigations).

Table
17:
MeBr
Industrial
Applicators
Exposures
and
Risks.

Scenario
Number
of
ND
Samples
Duration
of
Maximum
Sample
Result
Sample
time
Max.
Conc.
1
Monitored
PF10
Resp.*
Acute
MOE
Mean
Conc.
1
Monitored
PF10
Resp.*
Short­
and
Intermediateterm
MOE
Chronic
MOE
Based
On
Mean
Conc.

Remote
Applicator
(
n=
10)
3
9
0.35
to
101
6.5
5
2.6
2
<
1
0.65
46
0.26
17
2
Cannister
Opener
(
n=
13)
1
5
5
to
91
6100
<
1
1100
<
1
<
1
0.62
48
0.11
40
5
Aerator/
Venter
(
n=
32)
7
19
6
to
406
9500
<
1
590
<
1
<
1
0.95
32
0.059
75
9
*
For
remote
applicator,
a
PF
10
respirator
is
generally
used
for
mitigation.
For
the
others
SCBA
is
generally
used
and
has
a
10,000
protection
factor
associated
with
it.

1.
Concentrations
are
measured
in
ppm.
For
HECs
used
to
calculated
risks
for
each
duration,
see
Table
4/
page
15.

10.0
Data
Needs
and
Label
Requirements
10.1
Toxicology
None
at
this
time.

10.2
Residue
Chemistry
Based
upon
the
available
residue
data
and/
or
changes
in
data
requirements,
HED
is
recommending
changes
to
use
directions.
The
recommended
label
amendments
are
listed
in
the
Reregistration
of
Methyl
bromide:
Product
and
Residue
Chemistry
Chapters
to
the
Reregistration
Eligibility
Document
(
DP
Barcode
D271583;
C.
Olinger
memo
date
February
22,
2002).

10.3
Occupational
and
Residential
Exposure
The
assessment
of
occupational
and
residential
risks
associated
with
the
use
of
methyl
bromide
is
complex.
There
was
a
significant
amount
of
data
available
but
additional
data
are
still
required.
These
include
both
occupational
monitoring
of
various
workers
in
different
industry
sectors
and
data
to
better
assess
exposures
in
the
general
population.
The
types
of
data,
guideline
citations,
and
examples
of
the
scenarios
which
need
to
be
addressed
are
presented
below.
Final
determination
of
the
scenarios
should
be
made
in
consultation
with
the
Agency.

OPPTS
Guideline
875.1400
­
Inhalation
exposure
for
applicators
(
indoors)
63
Commodity
­
(
e.
g.,
Fumigators,
Material
Handlers,
Aerators)
Industrial
­
(
e.
g.,
Fumigators,
Material
Handlers,
Aerators)
64
OPPTS
Guideline
875.2500
­
Inhalation
exposure
for
postapplication
workers
Commodity
­
(
e.
g.,
forklift
drivers,
sorters,
packagers)
Industrial
­
(
e.
g.,
line
workers,
forklift
drivers)

Requirements
For
Special
Studies
Meteorological
Data
For
Probabilistic
Modeling
Purposes
Product
Use
Information
By
Major
Use
Region,
Frequency,
Application
Parameters
(
e.
g.,
rate,
amounts
treated,
data,
application
equipment
and
emission
control
technologies
used)

Measurements
of
indoor
air
concentrations
for
residences
in
proximity
of
treated
facilities.