Document ID: EPA-HQ-OPPT-2005-0032-0035
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2005-08-03T04:00Z

PRELIMINARY
EXPOSURE
ASSESSMENT
SUPPORT
DOCUMENT
FOR
THE
TSCA
SECTION
21
PETITION
ON
LEAD
WHEEL­
BALANCING
WEIGHTS
Office
of
Pollution
Prevention
and
Toxics
U.
S.
Environmental
Protection
Agency
August
3,
2005
NOTICE
This
document
has
been
prepared
by
the
U.
S.
Environmental
Protection
Agency,
Office
of
Pesticides,
Prevention
and
Toxic
Substances,
Office
of
Pollution
Prevention
and
Toxics.
The
use
of
trade
names
or
commercial
products
in
this
document
does
not
constitute
Agency
endorsement
or
recommendation
for
use.
TABLE
OF
CONTENTS
EXECUTIVE
SUMMARY
1.0
INTRODUCTION
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6
2.0
OVERVIEW
OF
THE
LIFE
CYCLE
OF
WHEEL­
BALANCING
WEIGHTS
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7
3.0
OVERVIEW
OF
LITERATURE
SEARCH
ON
GENERAL
POPULATION,
CONSUMER,
AND
ENVIRONMENTAL
EXPOSURE
TO
LEAD
WHEEL­
BALANCING
WEIGHTS
.
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8
4.0
FATE
OF
LEAD
IN
THE
ENVIRONMENT
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10
4.1
Environmental
Fate
of
Lead
in
Surface
Water
and
Sediments
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10
4.2
Sorption
of
Lead
in
the
Environment
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11
4.3
Environmental
Fate
of
Lead
Wheel­
balancing
Weights
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12
5.0
EXPOSURE
SCENARIOS
ASSOCIATED
WITH
POTENTIAL
RELEASES
OF
LEAD
TO
THE
ENVIRONMENT
FROM
LEAD
WHEEL­
BALANCING
WEIGHTS
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12
5.1
Inhalation
of
Airborne
Dust
In
and
Near
Roadways
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14
5.2
Dust
from
Roadways
Migrating
to
Residential
Front
Yards
(
ingestion
of
yard
soils
route,
i.
e.,
soil
to
mouth)
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17
5.3
Dust
Migrating
into
Residence
via
Pathways
5.1
and
5.2
Above
(
i.
e.,
dust
from
road
into
residence,
and
dust
from
soil
in
yard
into
residence);
And
Dust
into
Residence
from
Residential
Yards
via
Tracking
into
House
(
i.
e.,
ingestion
of
dust
that
has
settled
in
the
home
and
inhalation
of
airborne
dust
that
has
entered
the
home)
.
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19
5.4
Weights/
particles
Swept
Up
by
Municipal
Street
Cleaners
and
Incinerated
(
i.
e.,
inhalation
of
airborne
releases
from
incinerator)
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20
5.5
Weights/
Particles
Swept
Up
by
Municipal
Street
Cleaners
and
Landfilled,
Leading
to
Increased
Levels
of
Lead
in
Groundwater,
and
Reaching
Nearby
Drinking
Water
wells
(
ingestion
of
drinking
water
route)
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22
5.6
Vapors
from
Home
Smelting
of
Used
Wheel­
Balancing
Weights
Obtained
by
Non­
Commercial
Persons
from
Gas
Stations
and
Small
Wheel­
Balancing
Retailers
(
i.
e.,
inhalation
of
airborne
releases
from
home
smelter)
.
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27
5.7
Weights
Left
on
Cars
That
May
Be
Collected
and
Burned
in
Electric
Arc
Furnaces
(
i.
e.,
inhalation
of
airborne
releases
from
furnace)
And
Releases
Associated
with
Auto
Shredder
Activities
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
shredder)
.
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29
5.8
Releases
from
Roadways
to
Streams
­
Aquatic
Life
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30
6.0
DATA
GAPS
AND
UNCERTAINTIES
ASSOCIATED
WITH
ENVIRONMENTAL
AND
HUMAN
HEALTH
EXPOSURE
ASSESSMENT
OF
LEAD
WHEEL­
BALANCING
WEIGHTS
.
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33
APPENDICES
A
Summary
of
Environmental
Lead
Literature
Search
on
Lead
Wheel­
Balancing
Weights
43
LIST
OF
TABLES
1.
Hypothetical
Exposure
Concentrations
of
Lead
from
Roadside
Soil
using
ISC
.
.
.
.
.
.
.
16
2.
Hypothetical
Exposure
Concentrations
of
Lead
from
Wheel­
balancing
Weights
Swept
up
from
Streets
and
Incinerated,
Estimated
using
E­
FAST
.
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.
21
3.
Hypothetical
Exposure
Concentrations
of
Lead
from
Wheel­
balancing
Weights
Swept
up
from
Streets
and
Landfilled,
Estimated
using
E­
FAST
.
.
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.
25
4.
Estimated
surface
water
concentrations
from
lead
run­
off
.
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32
5.
Summary
of
Uncertainties
and
Data
Gaps
Table
associated
with
Lead
Wheel­
Balancing
Weight
Exposure
Assessment
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33
­
5­
EXECUTIVE
SUMMARY
EPA
has
reviewed
the
supporting
information
included
with
the
petition,
as
well
as
other
available
information
on
lead
wheel­
balancing
weights
and
concludes
that
additional,
verifiable
data
is
needed
in
order
to
develop
a
quantitative
assessment
of
the
potential
environmental
and
human
health
exposures
associated
with
releases
to
the
environment
from
lead
wheel­
balancing
weights.
In
particular,
as
described
in
further
detail
in
section
6.0
of
this
report,
data
is
needed
on
the
following
topics:
a)
amount
of
lead
wheel­
balancing
weights
that
are
lost
per
year
to
roadways
on
a
national
scale,
b)
the
variables
and
the
exposure
pathway
for
the
lead
wheel­
balancing
weights
falling
off
tires,
c)
the
variables
and
the
exposure
pathway
for
a
solid
lead
wheelbalancing
weight
to
be
converted
into
lead
that
is
bioavailable,
d)
the
distribution
of
lead
in
the
asphalt,
water,
soil,
air
from
lead
wheel­
balancing
weights
deposited
nationwide,
e)
the
geographical/
climatic/
socioeconomic
factors
that
would
increase/
decrease
the
number
of
wheelbalancing
weights
lost
to
streets;
and
f)
the
amount
of
lead
emitted
to
the
environment
during
home
smelting
operations.

The
EPA
has
developed
an
evaluation
of
potential
exposures
to
the
environment
and
humans
from
the
manufacture
and
use
of
lead
wheel­
balancing
weights
based
on
the
available
data
and
information.
The
available
data
with
which
to
construct
the
exposure
assessment
is
quite
limited,
especially
in
determining
the
quantity
of
lead
which
results
from
the
manufacture
and
use
of
lead
wheel­
balancing
weights
in
the
environment.
Because
of
this
important
limitation,
the
exposure
assessment
presented
in
this
report
is
based
on
"
what­
if
scenarios".
This
exposure
assessment
presents
hypothetical
estimates
of
exposure
which
are
based
on
available
data
and
information
and
postulated
questions
which
are
specific
to
the
assessment.
The
assumptions
made
in
answering
these
assessment­
specific
postulated
questions
do
not
give
information
about
how
likely
the
combination
of
values
might
be
in
the
actual
population
or
about
how
many
(
if
any)
members
of
a
population
might
actually
be
subjected
to
the
estimated
concentration.
The
hypothetical
estimates
of
exposure
are
helpful
in
evaluating
postulated
questions
such
as
"
What
if
all
of
the
lead
wheelbalancing
weights
on
1
million
vehicles
traveling
on
a
one
mile
stretch
of
road
over
one
year
entered
the
environment?"
These
hypothetical
estimates
of
exposure
provide
context
for
consideration
but
do
not
provide
information
on
how
likely
the
combination
of
values
might
be
in
the
real
world
and
therefore
should
not
be
used
in
a
risk
assessment.
­
6­
1.
0
INTRODUCTION
A
petitioner
has
requested
that
EPA
establish
regulations
prohibiting
the
manufacture,
processing,
distribution
in
commerce,
use,
and
improper
disposal
of
wheel­
balancing
weights
made
from
lead
(
Ecology
Center,
2005).
This
report
provides
background
information
on
EPA's
consideration
of
exposure
analyses
to
support
the
Agency's
response
to
this
petition.
This
exposure
assessment
utilizes
an
exposure
scenario
approach,
whereby
EPA
has
attempted
to
determine
the
concentrations
of
lead
in
a
given
environment
or
location
and
link
the
concentrations
with
the
time
that
the
identified
population
is
in
the
exposure
scenario.
The
scenario
evaluation
approach
uses
the
estimated
concentration
of
lead
in
the
identified
environment
and
estimated
time
of
contact
data,
as
well
as
information
on
the
potentially
exposed
population.

It
is
important
to
note
that
the
level
of
detail
of
an
assessment
is
a
function
of
the
amount
of
resolution
of
the
data
used
in
the
assessment
and
the
sophistication
of
the
analysis
prepared.
If
very
limited
data
is
available
and
many
assumptions
are
needed
in
order
to
develop
the
exposure
assessment,
a
hypothetical
exposure
scenario
assessment
which
is
simple
to
perform
and
which
poses
hypothetical
questions
such
as
"
What
is
the
exposure
to
an
individual
if
all
of
the
lead
wheel­
balancing
weights
from
a
million
cars
traveling
a
1
mile
distance
of
road
over
one
year
are
deposited
in
an
area
1
to
20
meters
from
the
roadway,
and
a
person
is
standing
there?"
may
be
the
best
that
can
be
done.
Detailed
exposure
assessments
provide
an
in­
depth
evaluation
of
exposure.
The
approach
used
for
a
detailed
exposure
assessment
is
to
use
the
best
data
available
and
develop
the
best
estimate
of
the
spatial
and
temporal
distributions
of
chemicals.
Detailed
exposure
assessments
typically
require
much
more
data
of
higher
quality,
and
in
the
absence
of
data,
models
of
greater
sophistication
(
USEPA,
1992a).

The
available
data
with
which
to
construct
the
exposure
assessment
for
lead
wheelbalancing
weights
is
quite
limited,
especially
in
determining
the
quantity
of
lead
in
the
environment
that
results
from
the
manufacture,
processing,
distribution
in
commerce,
use,
and
improper
disposal
of
wheel­
balancing
weights
made
from
lead.
Because
of
this
important
limitation,
the
exposure
assessment
presented
in
this
report
is
based
on
"
what­
if
scenarios."
This
exposure
assessment
presents
hypothetical
estimates
of
exposure,
which
are
based
on
available
data
and
information.
These
hypothetical
estimates
of
exposure
provide
context
for
consideration
but
do
not
provide
information
on
how
likely
the
combination
of
values
might
be
in
the
real
world
and
therefore
should
not
be
used
in
a
risk
assessment.

This
report
provides
the
results
of
EPA's
preliminary
exposure
assessment
for
the
TSCA
Section
21
petition
on
lead
wheel­
balancing
weights.
An
overview
of
the
life
cycle
analysis
of
lead
wheel­
balancing
weights
follows
in
section
2.0.
In
section
3.0,
an
overview
of
the
literature
search
on
lead
wheel­
balancing
weights
is
provided.
A
general
discussion
of
the
fate
of
lead
in
the
environment
is
given
in
section
4.0.
Section
5.0
provides
the
detailed
exposure
scenarios,
followed
by
conclusions
and
references.
Finally,
section
6.0
describes
the
relevant
data
gaps
and
­
7­
uncertainties
associated
with
environmental
and
human
health
exposure
assessment
of
lead
wheelbalancing
weights.

2.0
OVERVIEW
OF
THE
LIFE
CYCLE
OF
WHEEL­
BALANCING
WEIGHTS
The
lifecycle
of
lead
wheel­
balancing
weights
includes
the
manufacturing
in
primary
and
secondary
lead
smelting,
processing
at
lead
wheel­
balancing
weight
producers,
consumer
use
in
tires,
and,
other
end
uses,
i.
e.,
recycling
into
other
products,
reuse
as
fishing
weights
and
lures,
disposal
in
landfills/
incinerators.
Each
of
these
stages
is
discussed
briefly
below.

In
primary
lead
smelting,
mined
lead
ore
is
typically
processed
using
the
following
operations:
sintering,
smelting
in
a
blast
furnace,
the
drossing
process,
and
finally,
refining
before
being
cast
or
made
into
alloys.
A
lead­
antimony
alloy
is
the
most
commonly
produced
alloy
for
lead­
wheel­
balancing
weight
use.
Lead
releases
occur
during
primary
smelting,
and
they
include:
air
emissions,
process
wastes
(
i.
e.,
liquid
wastes
from
wastewater
and
slurries),
and
solid
wastes
(
i.
e.,
blast
furnace
slag).
Air
emissions
are
typically
controlled
by
baghouse
filters.
Liquid
wastes
are
considered
RCRA
K065
hazardous
wastes
and
transported
to
a
RCRA­
approved
waste
facility.
Solid
wastes
such
as
slag
are
usually
reused
or
treated
to
recover
metals
(
USEPA,
1995).

During
secondary
lead
smelting,
various
sources
of
processed
lead
are
combined
together
in
a
blast
furnace,
including
scrap
lead
from
batteries,
cable
coverings,
pipes,
lead
coated
(
or
terne
coated)
metals,
and
used
lead
wheel­
balancing
weights.
After
processing
in
the
blast
furnace,
the
product
enters
smelting
and
casting
steps
similar
to
primary
lead
smelting.
The
predominant
lead
releases
during
secondary
smelting
include
air
emissions
and
solid
waste.
Dust
is
generated
from
breaking
batteries
and
slag
during
the
smelting
process,
and
these
emissions
are
collected
and
disposed
of
as
RCRA
K069
hazardous
wastes
(
USEPA,
1995).
Portions
of
this
release
are
expected
to
include
lead
associated
with
wheel­
balancing
weights.

The
cast
ingots
and
alloys
from
primary
and
secondary
lead
smelters
are
sold
to
lead
wheel­
balancing
weight
producers
to
be
recast
into
wheel­
balancing
weights.
EPA
estimates
that
50
to
60
million
pounds
a
year
of
lead
go
into
lead
weight
manufacture
(
USEPA,
2005a)
.
Typically
5%
of
the
alloy
is
comprised
of
antimony.
Lead
wheel­
balancing
weights
are
then
sold
to
weight
distributers,
tire
manufacturers,
and
tire
retailers.
The
tire
manufactures
and
retailers
apply
the
weights
to
the
vehicle
when
balancing
new
and
used
vehicle
tires.

An
unintentional
release
of
these
weights
occurs
when
the
lead
weights
"
fly
off"
when
a
vehicle
is
jarred
or
during
sudden
velocity
changes.
These
abrupt
velocity
changes
are
typical
in
urban
areas
because
there
is
a
higher
traffic
loading
and
the
increased
number
of
required
stops,
(
i.
e.,
stop
lights,
stop
signs,
buses,
etc.).
The
Root
study
estimated
that
55
million
pounds
(
25
million
kilograms)
of
lead
exist
on
American
cars
and
light
trucks
and
that
33
million
pounds
(
15
million
kilograms)
of
lead
exists
on
urban
vehicles
(
Root,
2000).
The
study
calculated
an
annual
lead
loss
rate
of
10%
and
claimed
that
the
lead
is
further
broken
down
into
smaller
pieces
or
­
8­
ground
into
a
dust
by
traffic
although
no
data
were
provided
to
support
this
claim
.
Root
estimated
that
3.3
million
pounds/
yr
(
1.5
million
kg/
yr)
of
lead
are
deposited
in
urban
streets
and
claimed
this
residual
lead
can
be
washed
into
waterways
or
sewers,
migrate
into
nearby
residential
yards
or
land,
or
become
airborne
particulates
(
Root,
2000).
However,
no
data
or
studies
were
provided
that
show
how
or
how
much
of
the
lead
from
wheel­
balancing
weights
would
be
partitioned
to
the
various
media.
This
data
is
necessary
in
accurately
quantifying
exposures
to
lead
wheel­
balancing
weights.

Many
used
wheel­
balancing
weights
are
recycled.
It
is
estimated
that
50
(
to
60)
million
pounds
(
22.7
million
kg)
of
lead
per
year
are
used
to
make
lead
wheel­
balancing
weights
in
the
United
States.
Out
of
that
50
million
pounds,
it
is
estimated
that
16
million
pounds
are
sent
to
secondary
lead
smelters
for
recycling,
5
million
pounds
of
lead
are
sent
to
the
used
weight
market
for
reuse,
and
8
million
pounds
may
be
processed
in
automobile
recycling.
Therefore,
approximately
21
million
pounds
of
lead
used
in
wheel­
balancing
weights
are
unaccounted
for
in
these
estimates
(
Gust,
2004).
It
was
noted
by
Gust
that
approximately
1.5
million
pounds
of
offspec
wheel­
balancing
weights
and
other
lead­
containing
waste
are
collected
each
year
from
process
waste
streams
by
lead
wheel­
balancing
weight
manufacturers.

3.0.
OVERVIEW
OF
LITERATURE
SEARCH
ON
GENERAL
POPULATION,
CONSUMER,
AND
ENVIRONMENTAL
EXPOSURE
TO
LEAD
WHEEL­
BALANCING
WEIGHTS
EPA
conducted
a
literature
search
for
lead
wheel­
balancing
weights
and
associated
exposure
pathways
and
assessments.
EPA
conducted
literature
searches
in
the
PubMed,
ToxLine,
AGRICOLA,
Science
Direct,
and
DIALOG
databases,
as
well
as
general
Internet
searches
using
the
GOOGLE
search
engine.
A
summary
of
the
literature
search
is
provided
as
Appendix
A
to
this
document
(
USEPA,
2005b).
A
brief
overview
of
the
key
findings
from
the
literature
search
is
provided
below.

°
In
general,
the
availability
of
data
and
information
on
exposure
to
lead
from
the
manufacture
and
use
of
lead
wheel­
balancing
weights
is
very
limited.
Specific
documents
that
included
some
information
on
lead
wheel­
balancing
weights
include:
California
Department
of
Transportation
Environmental
Program
Proposed
Soil
Lead
Management
Criteria
as
Part
of
Caltrans
Highway
Construction
and
Maintenance
(
Lee
and
Taylor,
1998);
Environmental
Defense,
Ecology
Center,
Clean
Car
Campaign
Getting
the
Lead
Out
­
Impacts
of
and
Alternatives
for
Automotive
Lead
Uses
(
Gearhart,
et.
al.,
2003);
Lead
Loading
of
Urban
Streets
by
Motor
Vehicle
Wheel
Weights,
Robert
A.
Root
(
Root
2000);
and
Lead
Use
in
Ammunition
and
Automotive
Wheel
Weights:
An
Examination
of
Lead's
Impact
on
Environmental
and
Human
Health,
the
Alternatives
to
Lead
Use,
and
the
Case
for
a
Voluntary
Phase­
Out
(
Bodanyi,
2003).

°
The
internet
sites
managed
by
EPA
provide
generic
monitoring
data
on
lead
wheel­
­
9­
balancing
weights
and
the
toxicity
of
lead
but
do
not
provide
information
on
exposure
pathways
specifically
for
lead
wheel­
balancing
weights.

°
The
references
cited
in
the
TSCA
petition
also
did
not
provide
information
on
exposure
to
lead
wheel­
balancing
weights.
The
referenced
papers
did
provide
information
regarding
urban
runoff
and
lead
concentrations
in
the
runoff.
The
papers
also
provided
some
information
on
the
percentage
vehicular
traffic
played
in
regards
to
lead
in
the
urban
runoff.
However,
there
were
no
specific
references
to
lead
wheel­
balancing
weights,
save
the
Root
(
2000)
and
Bodanyi
(
2003)
papers.

°
Analyses
regarding
previous
EPA
rulemakings
(
e.
g.,
EPA's
TRI
Lead
rule,
the
lead
based
paint
debris
rule,
and
the
hazard
standards
for
lead­
based
paint
and
lead
in
dust
and
soil)
were
covered
in
Internet
searches.
In
particular,
the
lead
in
dust
and
soil
was
covered
in
searches
on
www.
epa.
gov/
opptintr/
lead/
403risk.
html
and
www.
epa.
gov/
opptintr/
lead/
403risksupp.
html,
and
the
lead
based
paint
debris
rule
was
covered
in
searches
at
www.
epa.
gov/
epaoswer/
non­
hw/
muncpl/
landfill/
pb­
paint.
htm.
Exposure
pathway
scenarios
were
identified,
but
they
focused
primarily
on
residential
exposure
from
lead­
based
paint.

°
Additional
searches
of
EPA
documents
available
on
the
Internet,
of
lead
exposure
scenarios
on
military
or
civilian
shooting/
trap
ranges,
and
other
Internet
sites
did
not
provide
exposure
data
of
relevance
to
lead
wheel­
balancing
weights.

Of
the
relevant
studies
identified,
the
Root
(
Root,
2000)
and
Bodanyi
(
Bodanyi,
2003)
studies
provided
the
most
information
on
exposure
to
lead
wheel­
balancing
weights,
but
these
studies
have
some
significant
shortcomings.
The
Root
study
performed
a
street
survey
where
lead
wheel­
balancing
weights
were
counted
along
eight
six­
lane
divided
street
segments,
totaling
19.2
km
in
an
urban
environment.
The
Root
study
uses
two
methods
to
estimate
the
rate
of
deposition
of
lead
from
wheel­
balancing
weights
from
their
counts.
However,
there
are
various
shortcomings
of
the
Root
study
that
limit
its
applicability
on
a
national
scale.
The
study
was
limited
in
geographic
scope.
The
Root
study
was
conducted
on
one
type
of
road
in
one
city
in
Arizona.
There
is
a
significant
potential
for
error
in
the
author's
detection
of
lead
wheelbalancing
weights
within
the
test
area.
The
cleaning
history
of
the
test
area
is
not
known.
The
nature
of
the
study
is
not
conducive
to
making
detailed
conclusions
about
what
happens
to
individual
wheel­
balancing
weights
during
their
time
on
the
road
surface,
i.
e.,
initial
ejection
from
a
car's
wheel
rim,
coming
to
rest
on
the
road
surface,
being
impacted
an
unknown
number
of
times
by
passing
vehicles,
and
(
possibly)
arriving
at
a
position
where
automobile
impacts
are
unlikely,
but
degradation
from
other
environmental
factors
may
continue
at
an
unknown
rate.
The
author's
assumptions
tend
to
overestimate
the
amount
of
lead
placed
into
the
environment
by
assuming
that
all
of
the
missing
wheel­
balancing
weights
were
pulverized
into
dust
and
distributed
into
the
environment.

Bodanyi
(
2003)
sought
to
corroborate
the
findings
of
the
Root
(
2000)
study
and
further
­
10­
characterize
the
loss
rate
of
lead
wheel­
balancing
weights
in
the
environment
using
a
street
and
parking
lot
survey.
While
the
study
was
largely
successful
in
the
former,
it
failed
in
the
latter
due
to
flaws
in
the
study
design.
The
study
is
not
published
and
did
not
go
through
the
peer
review
process.
Because
it
followed
the
methodology
of
the
Root
study,
the
Bodanyi
study
shares
many
of
the
Root
study's
shortcomings.

4.0
FATE
OF
LEAD
IN
THE
ENVIRONMENT
4.1
Environmental
Fate
of
Lead
in
Surface
Water
and
Sediments
The
concentration
of
dissolved
lead
in
water
is
controlled
by
many
factors
including
the
pH,
redox
potential,
concentration
of
inorganic
anions,
and
organic
contents
of
the
water
and
the
nature
of
the
organic
matter.
For
typical
dissolved
salt
levels
and
pH,
the
maximum
concentrations
of
lead
in
solution
in
hard
(
pH
>
5.4)
and
soft
(
pH
<
5.4)
water
is
about
30

g/
l
and
500

g/
l,
respectively
(
USEPA,
1977).
Long
and
Angino
(
1977)
studied
the
speciation
of
lead
as
a
function
of
pH
in
freshwater­
seawater
systems.
They
considered
complexes
of
the
type
PbL
n
at
pH
values
from
3.5
to
11
at
25

C
where
the
ligand,
L,
was
Cl­,
SO
4
2­,
HCO
3
­,
CO
3
2­,
and
OH­.
Results
were
presented
graphically
for
100%
freshwater,
50%
freshwater­
50%
seawater,
and
100%
seawater
as
the
percent
of
the
various
species
in
solution
as
a
function
of
pH.
In
freshwater,
free
Pb2+
was
the
dominant
species
below
pH
7.5,
above
which
complexes
with
CO
3
2­
(
PbCO
3)
dominated.
Above
pH
9.5,
(
OH)
2
2­
was
the
dominant
ligand.
In
seawater,
complexes
with
Cl­
(
PbCl+)
were
the
dominant
species
below
a
pH
of
about
8.3,
above
which
CO
3
2­
complexes
dominated
until
pH
9.5.
Chloride
and
carbonate
ions
are
the
major
ligands
at
a
pH
that
would
be
expected
in
estuaries
environments.
Complexing
with
chloride
increases
rapidly
with
minor
additions
of
seawater.

The
major
speciation
change
upon
addition
of
seawater
is
the
disappearance
of
free
Pb2+
and
the
appearance
of
chloride
complexes.
The
percentage
of
carbonate
complexing
does
not
change
appreciably
with
changes
in
other
ligand
concentrations.
Lead
carbonate
is
generally
the
controlling
factor
in
determining
the
solubility
of
lead
in
natural
waters.
Many
rivers
in
the
United
States
have
lead
concentrations
that
are
consistent
with
the
solubility
limits
determined
by
their
pH
levels
and
dissolved
CO
2
content.
Even
small
concentrations
of
carbonate
ions
due
to
the
dissolution
of
atmospheric
CO
2
are
sufficient
to
reduce
lead
concentrations
to
nearly
the
computed
solubility
limits
within
a
few
hour
(
Callahan
et
al.,
1979,
USEPA,
1986).
More
recently,
Fernando
(
1995)
calculated
the
distribution
of
Pb(
II)
species
in
seawater
as
a
function
of
chloride
concentration.
The
principal
lead
species
present
in
seawater
at
a
chloride
ion
concentration
of
0.56
M
are
PbCl
3
­
and
the
ion
association
complex
PbCO
3,
followed
by
PbCl
2
and
PbCl+.
It
is
interesting
to
note
that
even
at
this
high
chloride
ion
concentration,
there
is
a
significant
concentration
of
Pb(
OH)+
and
uncomplexed
Pb2+.

In
the
natural
environment,
water
contains
substances
other
than
the
major
inorganic
ions
­
11­
considered
by
Long
and
Angino
that
will
affect
lead
speciation
and
cycling.
In
a
speciation
study
of
lead
flowing
from
a
French
river
to
the
sea,
the
carbonate­
bound
and
exchangeable
lead
decreased
while
Fe­
Mn
oxide­
sorbed
and
organically­
bound
lead
increased
(
Elbaz­
Poulichet
et
al.,
1984).
These
changes
reflected
the
increased
levels
of
organic
matter
and
Fe­
Mn
oxides
in
the
seawater.
Changes
in
the
redox
potential
of
different
media
can
also
affect
speciation.
For
example,
a
chemical
equilibrium
model
of
the
Los
Angeles
County
sewage
indicates
that
lead
would
be
present
as
the
insoluble
sulfide
(
Morel
et
al.,
1975).
On
being
discharged
into
aerobic
seawater,
mobilization
would
be
expected,
although
no
significant
mobilization
was
demonstrated
in
laboratory
experiments
over
one
day
in
aerated
sewage­
seawater
mixtures.
Off
the
sewage
outfall,
lead
was
effectively
trapped,
and
even
showed
some
enrichment,
in
the
top
4
cm
of
reduced
sediment.

4.2
Sorption
of
Lead
in
the
Environment
A
large
fraction
of
lead
introduced
into
the
aquatic
environment
is
associated
with
suspended
solids
that
settle
down
into
the
sediments.
A
study
of
the
distribution
of
lead
between
filtrate
and
solids
in
stream
water
from
urban
and
rural
areas
reported
the
ratio
of
lead
in
suspended
solids
to
that
in
filtrate
varied
from
4%
in
rural
areas
to
27%
in
urban
areas
(
USEPA,
1977).
Cycling
of
lead
in
the
aquatic
environment
involves
a
complex
exchange
between
dissolved
and
particulate
phases.
Dissolved
phases
are
those
that
pass
through
a
filter
and
can
include
complexes
with
organic
ions
and
colloidal
organic
matter.
Particulate
lead
would
include
precipitates
formed
when
the
solubility
of
the
relevant
ions
is
exceeded,
lead
adsorbed
to
soil,
lead
associated
with
hydrous
oxides
of
iron,
manganese,
and
aluminum.

Lead
forms
strong
complexes
with
organic
matter.
Complexation
with
humic
acids
and
other
organic
complexing
agents
can
maintain
lead
in
a
bound
form
at
pH's
as
low
as
3
(
Callahan
et
al.,
1979).
Organic­
lead
interaction
increased
with
pH
and
decreased
with
water
hardness.
At
highly
polluted
sites,
the
high
anthropogenic
organic
content
of
the
water
controls
lead
speciation
(
Botelho
et
al.
1994).
In
surface
waters
of
Eastern
North
Pacific,
about
50%
of
the
total
lead
was
organically
complexed,
48%
was
complexed
with
inorganic
ligands,
and
about
1.4%
was
free
(
Capadaglio
et
al.,
1990).
No
difference
in
speciation
was
noted
between
filtered
and
unfiltered
samples
indicating
that
the
complexes
existed
in
a
dissolved
phase.

Sorption
also
appears
to
be
an
important
process
in
removing
lead
from
both
fresh
and
estuarine
natural
waters
into
sediment.
The
amount
adsorbed
depends
on
parameters
such
as
the
availability
of
ligands,
pH,
redox
conditions,
salinity,
iron
concentration,
composition
of
dissolved
particulate
matter
and
sediment,
and
lead
concentration
(
Callahan
et
al.,
1979).
Sorption
is
to
organic
matter,
clay
and
mineral
surfaces,
and
coprecipitation
and/
or
sorption
by
hydrous
iron
and
manganese
oxides.
Adsorptivity
increases
with
increasing
pH.
Lead
is
adsorbed
by
polar
particulate
matter
as
is
evidenced
by
its
dominance
in
sediment
of
specific
gravity
2.0­
2.9,
where
the
clay
fraction
is
found.
It
is
almost
absent
from
less
dense
sediment
fractions,
characterized
by
organic
matter
not
active
in
complex
formation,
or
denser
fractions,
characterized
by
precipitation
­
12­
(
Callahan
et
al.,
1979).
In
several
Kansas
streams,
lead
has
been
shown
to
be
highly
correlated
with
iron
and
manganese
in
sediment.
Another
study
showed
that
the
organic
content
of
bottom
mud
was
the
most
significant
factor
affecting
adsorptivity
(
Tada
and
Suzuki,
1982).
In
a
38­
day
intertidal
benthic
mesocosm
experiment,
lead
equally
distributed
between
the
dissolved
and
particulate
matter
in
the
water
column
during
high
tide,
with
the
levels
decreasing
during
ebb
tide
due
to
exchange
with
the
sediment,
porewater
and
benthic
fauna
(
Schulz­
Baldes
et
al.,
1983).
The
lead
accumulated
primarily
in
the
uppermost
centimeter
of
sediment.

4.3
Environmental
Fate
of
Lead
Wheel­
balancing
Weights
As
shown
in
Section
4.1
and
4.2,
general
information
on
the
fate
of
lead
in
the
environment
is
readily
available.
However,
no
data
were
found
in
the
literature
that
specifically
provided
information
on
the
fate
of
lead
wheel­
balancing
weights
in
the
environment.
Root
(
2000)
attempted
to
address
the
degradation
issue
by
distributing
a
known
quantity
of
wheelbalancing
weights
over
the
same
street
he
had
previously
surveyed
for
wheel­
balancing
weight
deposition.
Although
he
was
able
to
come
up
with
a
loss
rate,
EPA
believes
the
methodology
used
is
not
scientifically
valid
due
to
the
lack
of
controls.
For
example,
if
a
weight
disappeared,
the
study
design
assumed
that
this
lead
was
pulverized
into
dust
and
did
not
account
for
other
likely
and
possible
fates
of
the
weight,
such
as,
being
flipped
into
bushes,
becoming
bound
into
the
asphalt
of
the
street,
being
picked
up
by
a
street
cleaner
or
hobbyist,
etc.
There
were
no
soils
collected
at
the
side
of
the
road
and
analyzed
for
its
lead
content.
Air
sampling
was
not
performed
to
see
if
the
lead
became
air
borne.
Without
analytical
data,
EPA
believes
there
is
a
high
degree
of
uncertainty
associated
with
the
fate
of
lead
wheel­
balancing
weights.
With
a
better
designed
degradation
study
that
includes
testing,
more
accurate
data
would
be
available
for
use
in
preparing
a
quantitative
exposure
assessment.

5.0
EXPOSURE
SCENARIOS
ASSOCIATED
WITH
POTENTIAL
RELEASES
OF
LEAD
TO
THE
ENVIRONMENT
FROM
LEAD
WHEEL­
BALANCING
WEIGHTS
EPA
reviewed
the
literature
and
identified
the
most
likely
exposure
scenarios
associated
with
human
and
environmental
exposures
to
lead
wheel­
balancing
weights.
EPA
developed
the
following
nine
possible
exposure
scenarios
associated
with
releases
to
the
environment
from
lead
wheel­
balancing
weights:

a)
inhalation
of
airborne
dust
in
and
near
roadways
b)
dust
from
roadways
migrating
to
residential
front
yards
(
ingestion
of
yard
soils
route,
i.
e.,
soil
to
mouth)

c)
dust
migrating
into
residence
via
pathways
A
and
B
above
(
i.
e.,
dust
from
road
into
residence,
and
dust
from
soil
in
yard
into
residence);
and
dust
into
residence
from
residential
yards
via
­
13­
tracking
into
house
(
i.
e.,
ingestion
of
dust
that
has
settled
in
the
home
and
inhalation
of
airborne
dust
that
has
entered
the
home).

d)
weights/
particles
swept
up
by
municipal
street
cleaners
and
incinerated
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
incinerator).

e)
weights/
particles
swept
up
by
municipal
street
cleaners
and
landfilled,
leading
to
increased
levels
of
lead
in
groundwater,
and
reaching
nearby
drinking
water
wells
(
ingestion
of
drinking
water
route).

f)
vapors
from
home
smelting
of
used
wheel­
balancing
weights
obtained
by
non­
commercial
persons
from
gas
stations
and
small
wheel­
balancing
retailers
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
home
smelter).

g)
weights
left
on
cars
that
may
be
collected
and
burned
in
electric
arc
furnaces
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
furnace).

h)
releases
associated
with
auto
shredder
activities
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
shredder).

i)
releases
from
roadways
to
streams
­
aquatic
life
and
terrestrial
exposure
route
;
­
terrestrial
eats
aquatic
life
exposure
route
;
­
human
ingestion
of
drinking
water
route.

There
may
be
additional
potential
exposure
routes
associated
with
releases
to
the
environment
from
lead
wheel­
balancing
weights,
but
these
nine
scenarios
were
believed
to
be
the
most
likely
scenarios
based
on
the
Agency's
understanding
of
how
lead
wheel­
balancing
weights
are
manufactured
and
used.

Each
potential
exposure
route
is
described
in
further
detail
below.
Each
scenario
writeup
includes
a
discussion
of
available
data
regarding
wheel­
balancing
weight
losses
associated
with
the
route
of
exposure,
other
data
associated
with
lead
in
the
environment
in
media
associated
with
the
route
of
exposure,
the
method
used
to
calculate/
quantify
an
exposure
estimate
for
the
route
of
exposure,
and
limitations
and
uncertainties
associated
with
the
model/
calculation
method.

5.1
Inhalation
of
Airborne
Dust
In
and
Near
Roadways
5.1.1.
Available
data
regarding
wheel­
balancing
weight
losses
for
this
route
­
14­
Root
(
2000)
observed
an
annual
loss
rate
of
4E­
05
weights
per
vehicle­
mile
along
a
1
km
urban
thoroughfare
in
New
Mexico;
along
one
600­
m
section
with
a
higher
rate
of
stopping
and
turning
traffic,
the
loss
rate
was
8E­
05
weights
per
vehicle­
mile.
In
a
similar,
non­
peer­
reviewed
study
conducted
in
Michigan,
Bodanyi
(
2003)
observed
a
loss
rate
of
5E­
05
weights
per
vehiclemile
On
a
one­
mile
stretch
of
road
traversed
by
1
million
cars
per
year,
using
the
highest
of
these
loss
estimates
(
8E­
05
weights
per
year)
and
a
mean
weight
of
21
g
per
wheel­
balancing
weight,
the
estimated
lead
loading
is
1680
g/
yr
or
4.6
g/
day.

The
rate
at
which
wheel­
balancing
weights
are
ground
into
fine
particles
is
uncertain.
Root
(
2000)
placed
a
measured
quantity
of
wheel­
balancing
weights
along
an
urban
thoroughfare
that
had
previously
been
cleared
of
wheel­
balancing
weights
and
measured
the
rate
of
recovery
at
the
end
of
two
weeks.
He
calculated
a
daily
loss
rate
of
2.74%.
An
alternative
method
of
calculation,
based
on
a
loss
of
50%
of
lead
mass
in
8
days,
leads
to
an
estimated
loss
rate
of
6.25%
of
the
total
accumulated
lead
per
day.
It
should
be
noted
that
in
this
study,
any
lead
that
the
study
author
did
not
observe
on
his
inspection
of
the
test
area
was
considered
lost;
the
fate
of
this
lead
(
washed
away,
ground
to
dust,
or
simply
overlooked
due
to
intermingling
with
other
roadside
debris)
was
not
determined.

A
conservative
assumption
based
on
the
Root
(
2000)
study
would
be
that
each
day,
4.6
grams
of
lead
are
deposited
per
mile
of
road,
and
6.25%
of
the
lead
present
on
the
roadside
is
ground
to
dust.
There
are
significant
limitations
associated
with
the
Root
study,
as
described
in
section
3.0
of
this
document.

5.1.2.
Other
data
associated
with
lead
in
the
environment
in
media
associated
with
this
route
Howard
and
Sova
(
1993)
investigated
soil
lead
concentrations
in
soil
at
varying
depths
and
distances
from
interstate
highways
in
the
Detroit,
Michigan
area.
Concentrations
of
lead
in
all
forms
(
organic,
free,
exchangeable,
etc.)
in
shallow
soils
at
a
distance
of
10
m
from
the
roadside
ranged
from
23.8
to
374.7
mg/
kg,
a
range
that
is
1
to
2
orders
of
magnitude
higher
than
the
estimated
concentrations
found
in
the
Root
(
2000)
study
described
in
Section
3.0.
The
discrepancy
may
indicate
that
lead
wheel­
balancing
weights
are
only
a
small
contributor
to
the
total
lead
deposited
in
the
soil
near
highways.
The
concentrations
may
also
be
higher
if
the
lead
persists
in
the
soil
for
a
longer
period
than
that
assumed
by
Root,
i.
e.,
on
a
time
scale
of
decades
rather
than
years.

5.1.3.
Methods
used
to
calculate
"
what
if"
exposure
estimates
for
this
route:

A
first­
order
approximation
of
the
emission
rate
of
lead
from
roadside
soil
was
calculated
using
parameters
identified
by
EPA
and
derived
from
the
Root
(
2000)
and
Bodanyi
(
2003)
­
15­
studies.
This
emission
rate
was
used
as
an
input
in
a
fate
and
transport
model
in
a
hypothetical
exposure
scenario
for
a
person
standing
within
20
meters
of
the
roadside
emission
source.
The
following
assumptions
were
made:

S
the
exposed
person
is
standing
anywhere
from
1
­
20
m
from
the
road;

S
the
lead
wheel­
balancing
weight
emissions
from
the
road
are
treated
as
area
source
that
is
1609
m
x
0.6
m
(
965.4
m2).
This
conforms
to
a
road
1
mile
long,
with
the
lead
wheel­
balancing
weights
in
the
outer
curb
as
described
by
Root;

S
the
lead
wheel­
balancing
abrasion
occurs
constantly
during
14
hour
period
(
6
am
to
8
pm).
This
time
period
was
selected
as
being
the
most
probable
time
a
bystander
would
be
standing
next
to
the
road;

S
the
maximum
annual
wheel
weight
loss
is
8x10­
5
weights/
Vehicle
Mile
Traveled
(
VMT),
as
estimated
by
Root
(
2000)
and
Bodanyi
(
2003);

S
the
vehicular
traffic
along
the
one
mile
road
is
1x106
VMT/
year;

S
the
amount
of
lead
in
a
wheel
weight
is
approximately
21
g
Pb/
weight,
per
Root
(
2000);

S
the
lead
loading
in
the
soil
is
at
steady
state,
i.
e.,
the
stock
of
lead
in
the
soil
is
neither
increasing
nor
decreasing
over
the
long
term,
and
the
mass
emitted
per
day
is
equal
to
the
mass
deposited;

S
the
complete
pulverization
of
lead
wheel­
balancing
weights
and
equal
distribution
throughout
the
affected
area
is
on
a
short
time
scale
(<<
1
year);
and,

S
the
breathing
height
is
1.5
m
for
adults
and
1.2
m
for
a
child.
The
breathing
height
for
a
child
was
derived
from
the
average
height
estimated
using
CDC
Growth
Charts
for
boys
and
girls,
ages
5­
13
(
CDC,
2002).

To
model
air
concentrations,
the
Industrial
Source
Complex,
Short
Term
model
was
used.
A
series
of
268
rectangular
areas,
6m
x
0.6m,
were
assembled
to
model
the
emission
from
the
road.
A
conservative
wind
speed
of
1
m/
s
was
used
and
the
wind
was
assumed
to
blow
in
a
southeasterly
direction,
with
the
road
oriented
north
to
south.
As
the
bystander
would
be
standing
at
a
location
parallel
to
the
north­
south
orientation
of
the
road,
the
southeasterly
wind
direction
would
provide
the
most
conservative
exposure
concentration
estimate.
Four
stability
classes,
A­
D,
were
also
used
in
the
modeling,
as
these
would
be
the
most
prevalent
atmospheric
stability
categories
for
the
time
of
day
under
consideration.
It
was
assumed
that
the
bystander
would
be
located
between
1
to
20
meters
from
the
edge
of
the
street,
near
the
origin
of
the
modeling
runs.

In
the
ISC
model
analysis,
the
wet
and
dry
deposition
of
particles
on
surfaces
was
not
addressed.
The
complexity
of
the
modeling
of
these
transport
mechanisms
is
beyond
the
scope
of
this
"
what
if"
assessment,
and
each
model
run
may
take
up
to
several
days
of
computing
time,
putting
it
outside
the
realm
of
possibility
for
this
analysis.
This
aspect
of
the
exposure
pathway
may
be
revisited
in
the
future
using
the
ISC
model
if
more
definitive
source
information
becomes
available.
­
16­
(
/
)(
/)(
/
)

(
/
)(
/
)(
/
)(
.
)
8
10
1
10
21
365
14
3600
9654
5
6
2
x
weights
VMT
x
VMT
yr
gPb
weight
days
yr
hours
day
s
hour
m
 
Based
on
the
assumptions
above,
the
loss
of
lead
due
to
wheel­
balancing
weight
abrasion
was
estimated
at
9
x
10­
8
g
Pb/
m2­
s
(
see
calculation
below).

After
running
ISC,
the
maximum
hourly
average
concentration
was
estimated
using
the
worst
case
wind
speed/
stability
category
combination.
The
results
from
the
modeling
are
shown
in
the
table
1
below.
As
the
ISC
modeling
effort
was
used
to
generate
a
maximum
one
hour
average
concentration,
the
maximum
daily
average
concentration
and
the
maximum
annual
average
concentration
were
derived
using
conversion
factors
of
0.4
and
0.08,
respectively,
per
EPA
guidance
(
USEPA,
1992b).

Table
1.
Hypothetical
Exposure
Concentrations
of
Lead
from
Roadside
Soil
using
ISC
Distance
(
m)
Maximum
Hourly
Average
Concentration
(
µ
g/
m3)
Maximum
Daily
Average
Concentration
(
µ
g/
m3)
Maximum
Annual
Average
Concentration
(
µ
g/
m3)

Adult
Child
Adult
Child
Adult
Child
1
7E­
03
1E­
02
3E­
03
5E­
03
6E­
04
1E­
03
5
3E­
02
3E­
02
1E­
02
1E­
02
2E­
03
3E­
03
10
2E­
02
3E­
02
10E­
03
1E­
02
2E­
03
2E­
03
15
2E­
02
2E­
02
7E­
03
8E­
03
2E­
03
2E­
03
20
1E­
02
2E­
02
6E­
03
6E­
03
1E­
03
1E­
03
Exposure
point
concentrations
for
use
in
the
hypothetical
exposure
assessment
were
derived
from
the
maximum
(
across
all
distance
categories)
of
the
maximum
annual
average
concentration:
2E­
03
µ
g/
m3
for
adults
and
3E­
03
µ
g/
m3
for
children.

5.1.3.
Conclusions
drawn
from
this
analysis
As
stated
above,
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
Exposure
assessments
of
this
kind
should
be
considered
"
what­
if
scenarios".
At
the
time
of
this
assessment
there
was
no
data
available
to
determine
the
releases/
loading
of
lead
wheel­
balancing
weights
from
roadways
to
any
of
the
potential
exposure
routes;
therefore,
it
was
assumed,
for
purposes
of
these
initial
assessments,
that
all
releases
would
go
to
each
exposure
route
separately.
­
17­
This
assumption
is
highly
conservative,
since
it
is
very
unlikely
that
any
one
route
would
receive
the
entire
loading
of
lead
released
from
lead
wheel­
balancing
weights
left
on
streets.
Additional
well
designed
studies
could
fill
in
these
data
gaps
and
would
result
in
refined
and
improved
estimates.

5.2
Dust
from
Roadways
Migrating
to
Residential
Front
Yards
(
ingestion
of
yard
soils
route,
i.
e.,
soil
to
mouth)

5.2.1
Available
data
regarding
wheel­
balancing
weight
losses
for
this
route
Root
(
2000)
observed
an
annual
loss
rate
of
4E­
05
weights
per
vehicle­
mile
along
a
1
km
urban
thoroughfare
in
New
Mexico;
along
one
600­
m
section
with
a
higher
rate
of
stopping
and
turning
traffic,
the
loss
rate
was
8E­
05
weights
per
vehicle­
mile.
In
a
similar,
non­
peer­
reviewed
study
conducted
in
Michigan,
Bodanyi
(
2003)
observed
a
loss
rate
of
5E­
05
weights
per
vehiclemile
On
a
one­
mile
stretch
of
road
traversed
by
1
million
cars
per
year,
using
the
highest
of
these
loss
estimates
(
8E­
05
weights
per
year)
and
a
mean
weight
of
21
g
per
wheel­
balancing
weight,
the
estimated
lead
loading
is
1680
g/
yr
or
4.6
g/
day.
There
are
significant
limitations
associated
with
the
Root
study
as
described
in
section
3.0
of
this
document.

The
rate
at
which
wheel­
balancing
weights
are
ground
into
fine
particles
is
uncertain.
Root
(
2000)
placed
a
measured
quantity
of
wheel­
balancing
weights
along
an
urban
thoroughfare
that
had
previously
been
cleared
of
wheel­
balancing
weights
and
measured
the
rate
of
recovery
at
the
end
of
two
weeks.
He
calculated
a
daily
loss
rate
of
2.74%.
An
alternative
method
of
calculation,
based
on
a
loss
of
50%
of
lead
mass
in
8
days,
leads
to
an
estimated
loss
rate
of
6.25%
of
the
total
accumulated
lead
per
day.
It
should
be
noted
that
in
this
study,
any
lead
that
the
study
author
did
not
observe
on
his
inspection
of
the
test
area
was
considered
lost;
the
fate
of
this
lead
(
washed
away,
ground
to
dust,
or
simply
overlooked
due
to
intermingling
with
other
roadside
debris)
was
not
determined.

A
conservative
assumption
would
be
that
each
day,
4.6
grams
of
lead
are
deposited
per
mile
of
road,
and
6.25%
of
the
lead
present
on
the
roadside
is
ground
to
dust.

5.2.1.
Other
data
associated
with
lead
in
the
environment
in
media
associated
with
this
route
Other
data
available
for
this
pathway
are
discussed
in
the
summaries
in
section
5.1.2.

5.2.3
Methods
used
to
calculate
hypothetical
exposure
estimates
for
this
route
A
first­
order
approximation
of
the
lead
concentration
in
roadside
soil
was
calculated
using
­
18­
parameters
derived
from
the
Root
(
2000)
and
Bodanyi
(
2003)
studies.
The
following
assumptions
were
made:

S
a
loss
rate
of
8E­
05
weights
per
vehicle­
mile;

S
a
mass
of
21g
per
wheel­
balancing
weight;

S
a
traffic
rate
of
1,000,000
vehicles
per
year;

S
an
affected
area
of
roadside
soil
one
mile
long,
25
meters
wide,
and
1
inch
deep;

S
the
complete
pulverization
of
lead
wheel­
balancing
weights
and
equal
distribution
throughout
the
affected
area
on
a
short
time
scale
(<<
1
year);

S
a
soil
density
of
1.5
g/
cm3;

S
a
mean
residence
time
of
lead
in
soil
on
the
order
of
2
years
(
Watmough
et
al.,
2005);
and,

S
steady­
state
conditions.

Using
the
dimensions
listed
above,
the
lead
deposited
in
the
top
inch
of
soil
in
an
area
25
meters
wide
along
one
mile
of
road
in
one
year
would
result
in
a
lead
concentration
of
1
ppm.
For
a
mean
lead
residence
time
of
two
years,
under
steady­
state
conditions,
at
any
given
point
in
time
there
would
be
two
years'
accumulation
of
lead
deposits
in
the
affected
area,
which
may
be
expressed
as
a
concentration
of
2
ppm.
This
concentration
was
used
as
a
baseline
for
lead
concentration
in
affected
soils.

5.2.4.
Conclusions
drawn
from
this
analysis
The
estimated
hypothetical
soil
concentration
for
this
scenario
is
2
ppm
This
analysis
assumes
that
the
soil
to
which
individuals
are
exposed
have
the
same
level
of
contamination
as
the
roadside
soil;
in
other
words,
no
dispersion
or
attenuation
of
the
contaminated
soil
is
taken
into
account,
and
exposure
to
yard
soil
is
assessed
as
if
the
subject's
yard
is
entirely
within
the
affected
roadside
area.
This
assumption
would
tend
to
overestimate
the
level
of
exposure.

As
stated
above,
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
Exposure
assessments
of
this
kind
should
be
considered
"
what­
if
scenarios".
At
the
time
of
this
assessment
there
was
no
data
available
to
determine
the
releases/
loading
of
lead
wheel­
balancing
weights
from
roadways
to
any
of
the
potential
exposure
routes;
therefore,
it
was
assumed,
for
purposes
of
these
initial
hypothetical
scenario
assessments,
that
all
releases
would
go
to
each
exposure
route
separately.
This
assumption
is
highly
conservative,
since
it
is
very
unlikely
that
any
one
route
would
receive
the
entire
loading
of
lead
released
from
lead
wheel­
balancing
weights
left
on
streets.
Additional
well
designed
studies
could
fill
in
these
data
gaps
and
would
result
in
refined
and
improved
estimates.
­
19­
5.3
Dust
Migrating
into
Residence
via
Pathways
5.1
and
5.2
Above
(
i.
e.,
dust
from
road
into
residence,
and
dust
from
soil
in
yard
into
residence);
And
Dust
into
Residence
from
Residential
Yards
via
Tracking
into
House
(
i.
e.,
ingestion
of
dust
that
has
settled
in
the
home
and
inhalation
of
airborne
dust
that
has
entered
the
home)

5.3.1
Available
data
regarding
wheel­
balancing
weight
losses
for
this
route
The
available
data
for
this
pathway
are
discussed
in
the
summaries
for
Pathways
5.1
and
5.2.

5.3.2
Other
data
associated
with
lead
in
the
environment
in
media
associated
with
this
route
The
intake
of
household
dust
via
the
inhalation
and
dermal
routes
has
not
been
well
characterized.
U.
S.
EPA
(
2003a)
states
that
70%
of
indoor
dust
is
derived
from
outdoor
soil.
In
the
same
document,
indoor
dust
and
outdoor
soil
contribute
jointly
to
the
adult
soil
ingestion
rate
of
0.05
g/
day.
However,
the
amount
of
indoor
dust
inhaled
or
ingested
is
not
known.
As
a
worst­
case
scenario,
it
may
be
assumed
that
the
entire
daily
soil
ingestion
consists
of
indoor
dust,
of
which
70%
is
derived
from
outdoor
soil.
This
would
result
in
ingestion
exposure
levels
in
the
indoor
environment
that
are
30%
lower
than
those
determined
for
Pathway
5.2.
For
the
inhalation
route,
the
same
approach
may
be
taken
as
a
first­
order
approximation.
However,
this
approach
does
not
account
for
the
possibility
of
accumulation
of
lead
particles
in
the
indoor
environment,
but
rather
assumes
the
presence
of
outdoor
air
in
the
indoor
environment,
without
any
concentrating
effects
that
would
tend
to
increase
the
indoor
concentration.

5.3.3
Methods
used
to
calculate
hypothetical
scenario
exposure
estimates
for
this
route
For
this
pathway,
the
methods
and
sources
were
identical
to
those
for
the
ingestion
and
inhalation
scenarios.
Exposure
point
concentrations
were
reduced
by
30%
to
represent
a
scenario
in
which
100%
of
the
daily
contact
with
soil
was
through
contact
with
house
dust,
and
70%
of
the
house
dust
was
composed
of
outdoor
soil
that
entered
the
home
through
the
air
or
through
personal
contact
with
soil
(
i.
e.,
adherence
to
shoes
and
clothing).

5.3.4
Conclusions
drawn
from
this
analysis
As
stated
above,
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
Exposure
assessments
of
this
kind
should
be
considered
"
what­
if
scenarios".
At
the
time
of
this
assessment
there
was
no
data
available
to
determine
the
releases/
loading
of
lead
wheel­
balancing
weights
from
roadways
to
any
of
the
potential
exposure
routes;
therefore,
it
was
assumed,
for
purposes
of
these
initial
hypothetical
exposure
scenario
assessments,
that
all
releases
would
go
to
each
­
20­
exposure
route
separately.
This
assumption
is
highly
conservative,
since
it
is
very
unlikely
that
any
one
route
would
receive
the
entire
loading
of
lead
released
from
lead
wheel­
balancing
weights
left
on
streets.
Additional
well
designed
studies
could
fill
in
these
data
gaps
and
would
result
in
refined
and
improved
estimates.

5.4
Weights/
particles
Swept
Up
by
Municipal
Street
Cleaners
and
Incinerated
(
i.
e.,
inhalation
of
airborne
releases
from
incinerator)

This
hypothetical
exposure
scenario
assumes
wheel­
balancing
wheel
weights
that
are
lost
from
vehicles
to
the
streets
are
then
swept
up
by
municipal
street
cleaners
and
a
portion
of
them
are
incinerated.
The
amount
of
the
wheel­
balancing
weights
that
go
to
incinerations
is
apportioned
using
data
from
2003
(
USEPA,
2003b)
which
shows
14%
of
all
municipal
waste
goes
to
`
Combustion'.
For
this
assessment,
combustion
is
assumed
to
be
the
same
as
incineration.

5.4.1
Available
Data
regarding
wheel­
balancing
weight
losses
associated
with
this
route
Amount
of
lead
wheel­
balancing
weights
swept
up
by
municipal
street
cleaners.
No
data
or
studies
were
available
that
directly
measures
this
amount,
however,
Root
(
2000)
estimated
1.5
million
kg/
yr
of
lead
is
deposited
in
urban
streets.
The
Root
study
suggested
that
this
residual
lead
can
be
washed
into
waterways
or
sewers,
migrate
into
nearby
residential
yards
or
land,
or
become
airborne
particulates.
In
addition
to
these
pathways,
it
is
possible
that
municipal
street
cleaners
would
capture
the
lead
wheel­
balancing
weights
and
that
this
waste
could
then
be
incinerated.
For
this
scenario
it
is
conservatively
assumed
that
the
street
cleaners
remove
entire
amount
of
lead
wheel­
balancing
weights
from
the
road.
There
are
significant
limitations
associated
with
the
Root
study,
but
the
most
important
of
them
are
as
follows:
(
1)
it
is
limited
in
scope,
both
geographically
and
in
its
time
scale;
(
2)
error
may
results
from
imperfect
observation
of
wheel­
balancing
weights
during
the
weekly
surveys;
(
3)
street
sweeping
activities
were
not
accounted
for;
(
4)
no
attempt
is
made
to
measure
lead
in
soil
and
dust
near
the
test
area
and
establish
a
link
between
wheel­
balancing
weights
and
measured
lead
in
the
environment;
and
(
5)
the
route
of
human
exposure
to
lead
from
wheel­
balancing
weights
is
not
addressed.

The
amount
that
could
be
captured
is
estimated
as
follows:

Loading
in
kg/
yr
X
Portion
of
municipal
waste
to
incineration
=
Kg
of
Pb
wheel­
balancing
weights
per
unit
Number
of
Municipal
incineration
units
in
the
U.
S.
­
21­
(
1,500,000kg/
yr
X
0.14)/
167
units
=
1257
kg/
yr/
unit
Where,

Loading
=
1.5
Million
kg/
yr
of
lead
deposited
in
urban
streets
­
Root
(
2000)
Portion
of
municipal
wast
to
incineration
=
14.0%
of
municipal
solid
waste
goes
to
incineration
(
USEPA,
2003b).

Number
of
Municipal
incineration
units
in
U.
S.
=
There
are
66
large
municipal
incinerators
in
the
U.
S.
with
167
units
burning
waste
(
Stevenson,
2005).
This
assessment
assumed
that
an
equal
amount
of
the
waste
is
burned
in
each
of
the
167
units
as
a
`
what­
if'
assumption.

5.4.3
Method
used
to
calculate/
quantify
exposure
estimate
for
this
route
EPA/
OPPT's
Exposure
and
Fate
Screening
Assessment
Tool
(
E­
FAST)
was
used
to
estimate
exposure
to
an
adult,
child
and
infant
that
might
occur
as
the
result
of
Pb
Weights/
particles
being
swept
up
by
municipal
street
cleaners
and
incinerated
in
municipal
incinerators.
E­
FAST
uses
a
simple,
conservative
method
for
estimating
ambient
air
concentrations
that
may
result
from
air
emissions
from
sources
with
stacks
such
as
boilers
and
incinerators.
Maximum
annual
average
ground
level
air
concentrations
are
predicted
using
a
relationship
("
generic
ISCLT
model
method")
between
release
amount
and
maximum
annual
average
concentration
that
was
derived
by
OPPT
using
Industrial
Source
Complex
B
Long
Term
(
ISCLT)
modeling
of
emissions
from
a
hypothetical
facility.
The
calculations
for
the
derivation
of
concentrations
are
provided
in
the
Exposure
and
Fate
Assessment
Screening
Tool
(
E­
FAST)
Documentation
Manual
(
USEPA,
2000).
Hypothetical
air
concentrations
are
provided
in
table
2.

Table
2.
Hypothetical
Exposure
Concentrations
of
Lead
from
Wheel­
balancing
Weights
Swept
up
from
Streets
and
Incinerated,
Estimated
using
E­
FAST
Assumed
Destruction
and
Removal
Efficiency
%
Potential
Average
Daily
Concentration
(
mg/
m3)

0%
4E­
06
99%
4E­
08
99.9%
4E­
09
5.4.3
Conclusions
drawn
from
the
analysis
As
stated
above,
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
­
22­
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
An
exposure
assessment
of
this
kind
should
be
considered
a
what­
if
scenario.
At
the
time
of
this
assessment
there
was
no
data
available
to
determine
the
loading
of
lead
wheel­
balancing
weights
from
street
cleaners
to
each
incineration
unit;
therefore,
it
was
assumed
that
it
would
be
equally
distributed
to
all
incineration
units
in
the
United
States.
Also,
national
data
was
used
to
determine
what
percent
of
municipal
waste
is
combusted
and
does
not
necessarily
apply
to
the
Pb
wheelbalancing
weights
that
would
be
picked
up
by
street
cleaners
and
incinerated.
The
assumption
that
all
weights
would
be
picked
up
by
street
cleaners
as
opposed
to
being
picked
by
Do­
It­
Yourselfers
vs.
ground
into
the
asphalt
vs.
ground
into
dust,
etc.
is
highly
conservative.
Additional
well
designed
studies
could
fill
in
these
data
gaps
and
would
result
in
refined
and
improved
estimates.

5.5
Weights/
Particles
Swept
Up
by
Municipal
Street
Cleaners
and
Landfilled,
Leading
to
Increased
Levels
of
Lead
in
Groundwater,
and
Reaching
Nearby
Drinking
Water
wells
(
ingestion
of
drinking
water
route)

5.5.1
Available
Data
regarding
wheel­
balancing
weight
losses
associated
with
this
exposure
route
The
number
of
kilograms
of
lead
wheel­
balancing
weights
deposited
on
USA
highways
per
year
is
estimated
to
be
2,702,132
kg
lead.
(
Bodanyi,
2003).
Bodanyi's
estimate
of
2,702,132
kg
lead
wheel­
balancing
weights
deposited
on
USA
highways
per
year
was
estimated
based
on
a
calculation
that
multiplied
Bodanyi's
estimate
for
the
average
number
of
wheel
weights
lost
per
vehicle­
mile/
year
by
2.778
trillion
vehicle­
miles
traveled
in
the
USA
in
2001
(
NHTSA,
2002).
The
NHTSA
estimate
is
assumed
to
be
an
accurate
estimate
of
vehicle­
miles
traveled
in
the
USA.
The
Bodanyi
study
is
not
published
and
did
not
go
through
the
peer
review
process.
The
study
cites
a
reference
that
states
that
a
typical
car
has
ten
wheel
balancing
weights
 
two
on
each
wheel,
including
the
spare.
In
an
assessment
of
roadside
deposition
of
lead,
only
four
wheels
should
be
considered.

For
this
hypothetical
exposure
scenario
analysis,
EPA
assumed
that
the
lead
wheelbalancing
weight
loading
per
landfill
per
year
in
the
USA
would
be
1,529.22
kilograms
(
2,702,132
kg
lead
deposited
on
nations
highways
per
year
from
lead
wheel­
balancing
weights;
divided
by
1A
MSWLF
is
a
discrete
area
of
land
or
an
excavation
that
receives
household
waste
and
other
types
of
wastes
as
defined
under
Subtitle
D
of
the
Resource
Conservation
and
Recovery
Act
(
RCRA),
such
as
commercial
solid
waste,
nonhazardous
sludge,
small
quantity
generator
waste,
and
industrial
solid
waste.
Such
a
landfill
maybe
publicly
or
privately
owned.
(
USEPA
1993a).

­
23­
1767
(
the
number
of
municipal
solid
waste
landfills
(
MSWLF)
1
operating
in
USA
in
2002
with
capacity).
(
See
USEPA,
2005c).
This
estimate
is
very
conservative
because
it
assumes
that
all
wheel­
balancing
weights
deposited
on
USA
highways
are
swept
up
and
deposited
in
landfills.

The
number
of
available
MSWLFs
is
decreasing
over
time
but
appears
to
be
leveling
out.
The
available
landfill
capacity
has
remained
relatively
constant
over
time
because
newer
landfills
are
much
larger
than
those
built
many
years
ago
(
USEPA,
2003b).

The
hypothetical
exposure
scenario
analysis
assumption
that
all
wheel­
balancing
weights
deposited
on
USA
highways
are
swept
up
and
deposited
in
landfills
is
very
uncertain.
It
is
highly
conservative
to
assume
that
all
wheel­
balancing
weights
that
may
be
deposited
on
roadways
in
a
given
town
in
the
USA
for
a
given
year
are
swept
up
and
deposited
into
the
town's
landfill.

5.5.2
Other
data
associated
with
lead
in
the
environment
in
media
associated
with
this
route
Leach
Rate
information:

There
is
limited
data
available
regarding
the
leach
rate
of
lead
from
wheel­
balancing
weights
within
MSWLFs.
The
leach
rate
may
be
defined
as
the
amount
of
lead
that
dissolves
or
otherwise
is
released
from
the
lead
wheel­
balancing
weight
over
time.
One
report
published
by
Steil
(
2000)
identified
a
leaching
rate
of
0.88
g
from
a
wheel­
balancing
weight
during
a
12­
year
duration
of
use
and
a
10
cm2
surface
area.
As
described
further
below,
an
extrapolation
of
this
research
indicates
that
the
number
of
grams
that
could
leach
out
from
a
landfill
per
year
from
a
MSWLF
is
730
grams/
year,
based
on
the
following
calculations
and
assumptions:

a)
Average
wheel­
balancing
weight
mass:
21
grams
(
Root,
2000.)
b)
Average
leach
rate
per
year
per
wheel­
balancing
weight:
0.07
grams
(
0.88g/
12
years)
(
Steil,
2000.)
c)
Average
leach
rate
per
year
per
gram
of
wheel­
balancing
weight:
0.000476
grams
(
0.07
gram
per
year
leached
divided
by
21
grams
average
wheel­
balancing
weight
mass)

d)
Mass
of
wheel­
balancing
weights
deposited
in
a
MSWLF
per
year:
1,529,220
grams
(
2,702,132
kg
lead
deposited
on
nations
highways
per
year
from
lead
wheel­
balancing
weights;
divide
2,702,132
kg
by
1767
(#
MSWLF
landfills
operating
in
US
in
2002
with
capacity).
e)
Number
of
grams
leached
out
per
year
per
MSWLF:
730
grams/
year
(
0.000476
grams
x
1,529,220)
­
24­
There
is
limited
data
available
regarding
the
leach
rate
of
lead
from
wheel­
balancing
weights
within
MSWLFs
(
with
the
leach
rate
defined
as
the
amount
of
lead
that
dissolves
or
otherwise
is
released
from
the
lead
wheel­
balancing
weight
over
time).
It
is
uncertain
whether
Steil's
research
results
(
2000)
represent
expected
leach
rates
for
releases
that
would
occur
from
lead
wheel­
balancing
weights
disposed
within
municipal
landfills.
It
is
thus
uncertain
whether
an
extrapolation
of
this
research
would
be
appropriate
to
use
in
estimating
the
number
of
grams
that
could
leach
out
from
a
landfill
per
year
from
a
MSWLF.
Additional
data
would
be
preferable
regarding
the
expected
releases
of
lead
from
lead
wheel­
balancing
weights
in
a
landfill
environment.

5.5.3
Method
used
to
calculate/
quantify
exposure
estimate
for
this
Route
EPA's
Exposure
and
Fate
Assessment
Screening
Tool
(
EFAST)
model
was
used
to
calculate
a
preliminary,
hypothetical
exposure
scenarios
exposure
concentration
at
a
drinking
water
well
downgradient
of
a
landfill
that
is
assumed
to
have
received
a
loading
of
lead
wheelbalancing
weights.

EFAST
is
a
publicly
available
suite
of
models
that
contains
databases,
models
and
algorithms
for
screening­
level
exposure
assessment
of
chemical
releases
to
air,
water,
land,
and
from
consumer
products,
and
provides
detailed
information
on
environmental
fate
of
a
wide
variety
of
existing
chemicals.
A
description
of
EFAST
and
its
baseline
assumptions
and
methodology
is
summarized
below
.
Additional
details
on
EFAST
is
available
on
the
following
website:
http://
www.
epa.
gov/
opptintr/
exposure/
docs/
efast.
htm.

EPA
ran
the
EFAST
landfill
scenario
assuming
the
lead
wheel­
balancing
weight
loading
per
landfill
per
year
to
be
1,529.22
kilograms
(
2,702,132
kg
lead
deposited
on
nations
highways
per
year;
divided
by
1767
(
the
number
of
Municipal
solid
waste
landfills
operating
in
USA
in
2002
with
capacity)).
This
estimate
is
conservative
because
it
assumes
that
all
wheel­
balancing
weights
deposited
on
USA
highways
are
swept
up
and
deposited
in
landfills.
The
EFAST
model
output
for
Average
Daily
Concentrations
(
ADC)
of
lead
in
drinking
water
for
the
hypothetical
exposure
scenario
is
noted
below.

Table
3.
Hypothetical
Exposure
Concentrations
of
Lead
from
Wheel­
balancing
Weights
Swept
up
from
Streets
and
Landfilled,
Estimated
using
E­
FAST
­
25­
Slow
Migration
Rate
Average
Daily
Concentration
mg/
L
Rapid
Migration
Rate
Average
Daily
Concentration
mg/
L
1529.22
kg
to
landfill/
year;
365
days/
year
exposure
8E­
03
<<<
1
1146.10
kg
to
landfill/
year;
365
days/
year
exposure
5E­
03
2E­
02
766.50
kg
to
landfill/
year;
365
days/
year
exposure
3E­
03
1E­
02
383.25
kg
to
landfill/
year;
365
days/
year
exposure
2E­
03
5E­
03
The
above
concentrations
were
developed
using
EFAST
and
assuming
four
scenarios:
­
100%
of
lead
on
roadways
went
to
the
landfill
(
1529.22
kg
to
landfill/
year);
­
75%
of
lead
on
roadways
went
to
the
landfill
(
1146.1
kg
to
landfill/
year);
­
50%
of
lead
on
roadways
went
to
the
landfill
(
766.5
kg
to
landfill/
year);
and
­
25%
of
lead
on
roadways
went
to
the
landfill
(
382.25
kg
to
landfill/
year).

There
are
various
uncertainties
and
limitations
associated
with
the
use
of
EFAST
for
these
model
runs.
First,
EFAST
assumes
that
100%
of
the
lead
wheel­
balancing
weight
loading
per
year
to
the
landfill
(
1,529,220
grams)
was
released
to
the
groundwater.
This
is
a
very
conservative
assumption,
since
it
is
unlikely
that
100%
of
a
wheel
weight
would
dissolve
or
release
lead
within
one
year
of
the
time
of
disposal
within
a
landfill.
It
would
thus
be
more
realistic
and
reasonable
to
reduce
the
assumption
for
the
landfill
release
term
used
in
the
model
runs
for
landfill
leachate
resulting
from
lead
wheel­
balancing
weights.
An
extrapolation
of
limited
available
research
(
Steil,
2000)
indicates
that
the
number
of
grams
that
could
leach
out
from
the
assumed
lead
wheel­
balancing
weight
loading
per
year
to
a
MSWLF
landfill
(
1,529,220
grams)
could
be
730
grams/
year.
Additional
data
would
be
preferable
regarding
the
expected
releases
of
lead
from
lead
wheel­
balancing
weights
in
a
landfill
environment.

Second,
EFAST
model
runs
assume
that
the
lead
wheel­
balancing
weight
waste
is
being
disposed
of
in
an
unlined
landfill
with
no
leachate
collection
systems,
with
uncontrolled
releases
to
receptor
wells.
This
is
a
very
conservative
assumption,
since
it
is
likely
that
towns
and
cities
that
­
26­
dispose
of
municipal
waste
in
landfills
use
either
new
landfills
that
are
lined
with
leachate
collection
systems,
or
older
existing
landfills
that
are
required
to
monitor
groundwater
and
perform
corrective
action
to
contaminated
groundwater
if
necessary.

Two
basic
options
are
provided
for
in
the
federal
municipal
landfill
regulations
for
the
design
of
new
municipal
landfills
and
lateral
expansions
to
existing
municipal
landfills.
The
first
option
is
that
the
landfill
or
expansion
must
meet
the
EPA
performance
standard,
i.
e.,
that
Maximum
Contaminant
Levels
(
MCLs)
will
not
be
exceeded
in
the
uppermost
aquifer
at
a
"
relevant
point
of
compliance."
The
second
option
is
a
design
developed
by
EPA
that
consists
of
a
composite
liner
and
a
leachate
collection
system.
Also,
a
municipal
landfill
cannot
accept
bulk
or
noncontainerized
liquid
waste
unless
(
1)
the
waste
is
nonseptic
household
waste,
or
(
2)
it
is
leachate
or
gas
condensate
that
is
recirculated
to
the
landfill,
and
the
unit
is
equipped
with
a
composite
liner
and
leachate
collection
system
(
USEPA,
1993b).

The
federal
municipal
landfill
regulations
require
that
all
existing
MSWLF
units,
lateral
expansions
of
existing
units,
and
new
MSWLF
units
must
conduct
groundwater
monitoring
(
unless
a
State
that
is
delegated
the
RCRA
municipal
landfill
program
finds
that
no
potential
exists
for
migration
of
hazardous
constituents
from
the
MSWLF
unit
to
the
uppermost
aquifer
during
the
active
life
of
the
unit,
including
closure
or
post­
closure
care
periods).
If
a
significant
change
in
groundwater
quality
occurs,
the
federal
municipal
landfill
regulations
require
an
assessment
of
the
nature
and
extent
of
contamination
followed
by
an
evaluation
and
implementation
of
remedial
measures
(
USEPA,
1993b).
Additional
information
on
Federal
requirements
for
municipal
landfills
can
be
found
at
the
following
EPA
websites:
http://
www.
epa.
gov/
epaoswer/
non­
hw/
muncpl/
disposal.
htm
and
http://
www.
epa.
gov/
epaoswer/
non­
hw/
muncpl/
facts.
htm,
and
in
EPA's
Criteria
for
Solid
Waste
Disposal
Facilities
(
USEPA,
1993a).

Third,
additional
data
would
be
preferable
regarding
the
type
of
landfills
that
cities
and
towns
use
for
disposal
of
waste
collected
by
street
cleaning
machines.

5.5.4
Conclusions
drawn
from
the
analysis
As
stated
above,
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
An
exposure
assessment
of
this
kind
should
be
considered
a
what­
if
scenario.
At
the
time
of
this
assessment
there
was
no
data
available
to
determine
the
loading
of
lead
wheel­
balancing
weights
from
street
cleaners
to
landfills;
therefore,
it
was
assumed
that
it
would
be
equally
distributed
to
all
municipal
landfills
in
the
United
States.
The
assumption
that
unlined
landfills
without
leachate
collection
systems
would
be
used
for
disposal
of
lead
wheel­
balancing
weights
is
highly
conservative,
since
federal
regulations
for
municipal
landfills
require
use
of
lined
landfills
with
leachate
collection
systems.
The
assumption
that
all
lead
from
lead
wheel­
balancing
weights
­
27­
disposed
of
in
landfills
would
leach
within
a
year
is
also
highly
conservative,
since
it
is
unlikely
that
all
wheel­
balancing
weights
would
dissolve
or
release
all
lead
within
one
year
within
a
landfill.

Additional
well
designed
studies
could
fill
in
these
data
gaps
and
would
result
in
refined
and
improved
estimates.

5.6
Vapors
from
Home
Smelting
of
Used
Wheel­
Balancing
Weights
Obtained
by
Non­
Commercial
Persons
from
Gas
Stations
and
Small
Wheel­
Balancing
Retailers
(
i.
e.,
inhalation
of
airborne
releases
from
home
smelter)

Both
the
Office
of
Pollution
Prevention
and
Toxics
and
the
Office
of
Solid
Waste
identified
hobbyist
melting
and
recasting
of
lead
wheel
weights
as
a
source
of
potential
lead
exposure.
OSW
and
ORD
began
the
development
of
a
scenario
for
lead
exposure
from
this
use
that
considered
both
oral
and
inhalation
routes
of
exposure
for
individuals
collecting,
melting
and
casting
lead
wheel
weights
into
new
articles
for
commercial
sales.
The
scenario
was
intended
to
yield
lead
concentrations
in
relevant
media
for
use
in
biokinetic
models
to
predict
blood
lead
levels
in
exposed
individuals.
Although
key
variables
in
the
exposure
scenario
were
identified,
and
input
values
were
suggested
to
determine
if
the
scenarios
and
modeling
could
be
successfully
used,
no
input
values
based
on
measured
data,
or
documentation
for
the
selected
inputs
were
developed.
If
this
scenario
is
further
developed
so
that
it
includes
documented,
measured,
reliable
input
values,
then
it
would
be
helpful
in
developing
a
quantitative
exposure
assessment
of
the
home
smelting
of
lead
wheel­
balancing
weights.

5.6.1
Available
Data
regarding
lead
exposure
associated
with
this
route
There
are
many
sources
of
information
on
how
to
melt
and
cast
lead
into
various
products
(
bullets,
sinkers,
ingots),
but
no
quantitative
information
could
be
found
on
exposure
to
lead
during
the
process.
Virtually
all
of
the
lead
casting
equipment
manufacturers
supply
warning
information
with
their
products
on
lead
hazard
and
methods
to
minimize
exposure
during
product
use.

Lead
melts
at
approximately
327
degrees
C.
Melted
lead
gives
off
fumes
at
temperatures
above
500
degrees
C.
Lead
can
be
melted
by
the
hobbyist
using
a
variety
of
devices.
These
devices
range
from
cast
iron
pots
that
can
be
heated
using
any
heat
source
(
propane,
electric
heating
element,
etc.)
with
little
temperature
control,
to
electric
melting
pots
with
temperature
adjustment.
Electric
stoves
heating
elements
are
are
known
to
reach
a
temperatures
in
excess
of
660
C
causing
aluminum
cookware
to
fail
and
natural
gas
burns
at
a
range
of
1600
to
2000
degrees
C.
Thus
there
is
a
possibility
of
generating
lead
fumes
using
these
heat
sources.
At
least
one
major
manufacturer
of
electric
melting
devices
builds
their
equipment
to
heat
to
a
maximum
temperature
below
500
C
to
minimize
lead
fuming.

No
information
was
found
on
airborne
lead
concentrations
in
the
air
around
these
melting
­
28­
devices.
However,
workplace
air
monitoring
data
do
exist
for
industrial
operations
where
lead
is
melted.
Workplace
air
at
three
sites
in
the
fishing
tackle
industry
where
lead
sinkers
are
cast
was
monitored
for
lead.
Eight
hour
TWA
in
personal
breathing
zones
were
determined..
The
average
concentrations
for
job
category
lead
pot
tender
was
49
ug/
m3
(
OSHA,
1994).

Field
surveys
of
three
radiator
repair
shops
(
where
lead
containing
solder
is
used
for
repairs)
in
the
Cincinnati,
OH
area
showed
that
the
highest
concentration
of
airborne
lead
measured
during
a
brief
period
of
continuous
soldering
in
a
shop
equipped
with
local
exhaust
ventilation
was
7.1
µ
g/
m3.
In
a
shop
where
no
exhaust
was
used,
the
13
personal
samples
averaged
209
µ
g/
m3
with
a
maximum
of
810
µ
g/
m3
measured
for
a
56­
minute
sample
worn
while
tearing
down
and
resoldering
a
single
radiator
(
Tharr,
1993).

A
study
on
worker
exposure
to
lead
in
Korea
reported
geometric
mean
values
for
total
airborne
lead
concentrations
of
758
ug/
m3
in
secondary
smelting
furnace
operations,
436
ug/
m3
in
scrap
and
furnace
operations,
and
25
ug/
m3
in
radiator
soldering.

5.6.2
Other
data
associated
with
lead
in
the
environment
in
media
associated
with
this
route
No
specific
studies
on
the
fuming
of
lead
at
high
temperatures
were
found,
but
many
references
to
lead
fume
formation
at
temperatures
above
500
degrees
C
can
be
found
in
the
available
information
on
reducing
worker
exposure
to
lead
and
prevention
of
worker
lead
poisoning.
The
reported
vapor
pressure
of
lead
increases
from
10E­
6
Torr
at
429
Degrees
C
to
10E­
4
Torr
at
547
degrees
C,
supporting
the
potential
for
volatilization
as
temperatures
are
elevated.

5.6.3
Method
used
to
estimate
exposure
concentration
for
this
hypothetical
exposure
scenario
Due
to
a
number
of
considerations
(
see
5.6.4)
exposure
to
lead
in
this
scenario
was
not
estimated.
EPA
did,
however,
find
information
on
procedures
for
hobbyist
lead
melting
and
casting.
Generally
lead
is
added
to
the
melting
pot
and
melted
over
a
20­
30
minutes
period
while
the
contents
to
reach
about
600
F.
Temperature
may
be
adjusted
to
approximately
650
F
for
best
lead
flow
and
mold
fill­
out.
Lead
is
fluxed
as
needed
by
adding
a
small
amount
of
wax
or
flux,
stirring
vigorously
and
scraping
sides
and
bottom
of
pot
to
dislodge
impurities.
Impurities
are
then
skimmed
off
the
surface
of
the
melted
lead.
Once
lead
is
melted
the
mold
is
heated
by
dipping
a
corner
of
it
into
melted
lead
for
about
15
seconds.
When
the
mold
is
hot,
it
is
filled
with
molten
lead,
excess
lead
removed
(
sprue
cut
off)
and
allowed
to
cool
slightly.
The
mold
is
then
opened
and
the
object
tapped
out
into
a
soft
cloth.
The
length
of
the
casting
session
is
indeterminate
and
largely
dependent
on
the
desires
of
the
hobbyist.

5.6.4
Conclusions
drawn
from
the
analysis
­
29­
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenarios
evaluated.
It
is
not
possible
to
characterize
the
accuracy
of
the
scenario
because
each
hobbyist
may
use
different
procedures
which
could
result
in
more
or
less
exposure.
No
monitoring
data
were
available
for
this
scenario.
EPA
believes
that
the
use
of
airborne
lead
concentration
taken
from
workplace
monitoring
studies
would
result
in
unrealistically
high
estimated
exposures.
Information
on
the
routine
practices
for
hobbyist
lead
melting
and
casting
suggest
that
some
amount
of
exposure
is
possible,
but
reliable
quantitative
estimates
for
exposure
from
those
practices
cannot
be
made
at
this
time
due
to
lack
on
information
on
factors
including
airborne
concentrations
of
lead
generated
during
home
melting
and
the
prevalence
of
different
lead
melting
and
casting
practices.

5.7
Weights
Left
on
Cars
That
May
Be
Collected
and
Burned
in
Electric
Arc
Furnaces
(
i.
e.,
inhalation
of
airborne
releases
from
furnace)
And
Releases
Associated
with
Auto
Shredder
Activities
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
shredder)

5.7.1
Available
Data
regarding
wheel
weight
releases
associated
with
this
route
Automobile
shredders
(
AS):
There
are
200
automobile
shredding
facilities
in
the
U.
S.
which
are
assumed
to
operate
over
250
days
per
year.
There
are
no
studies
that
estimate
the
amount
of
lead
wheel
weights
processed
in
these
automobile
shredding
facilities.
Both
dust
and
water
releases
of
lead
are
possible,
the
amounts
released
could
not
be
quantified
due
to
the
lack
of
data
(
USEPA,
2005a)

Electric
Arc
Furnaces
(
EAF):
There
are
95
facilities
utilizing
EAF
in
the
U.
S.
with
workers
being
exposed
up
to
250
days/
year
(
USEPA,
2005a).
There
are
no
studies
that
estimate
the
amount
of
lead
wheel
weights
processed
in
these
EAF
facilities.
There
are
data
in
the
2003
Toxics
Release
Inventory
for
facilities
in
the
secondary
smelting
and
Reining
of
nonferrous
metals
industry
(
SIC
3341),
however,
these
lead
releases
are
from
all
operations
at
these
facilities.
The
amount
of
these
releases
that
is
associated
with
lead
wheel­
balancing
weights
cannot
be
ascertained
or
estimated
from
this
value
(
USEPA,
2005a).

5.7.2
Method
used
to
calculate/
quantify
exposure
estimate
for
the
EAF
pathway
There
were
no
release
estimates
available
from
either
shredder
operations
or
EAF
facilities
to
allow
EPA
is
estimate
exposure
via
these
pathways.
If
data
were
available,
the
Exposure
and
Fate
Screening
Assessment
Tool
(
E­
FAST)
which
uses
a
simple,
conservative
method
for
estimating
ambient
air
concentrations
that
may
result
from
air
emissions
from
sources
with
stacks
such
as
boilers
and
incinerators
(
and
in
this
case
electric
arc
furnaces)
could
be
used
to
estimate
exposure.
­
30­
5.7.3
Conclusions
EPA
was
unable
to
construct
a
hypothetical
exposure
scenario
due
to
the
lack
of
available
data
and
information,
specifically,
the
amount
of
lead
from
shredder
operation
and
EFA
facilities
that
is
associated
with
lead
wheel­
balancing
weights.
Additional
research
may
result
in
refined
and
improved
estimates.
Although
this
is
a
possible
scenario,
EPA
could
not
determine
what
likelihood
of
lead
wheel­
balancing
weights
being
left
on
ELVs
that
would
then
be
processed
in
Automotive
Shredder
(
AS)
facilities
and
subsequently
sent
to
EAF
facilities
in
the
U.
S.
There
is
no
information
available
at
this
time
to
make
any
assumption
on
what
amount
of
lead
wheel
weights
will
undergo
treatment
in
AS/
EAF
facilities.
Additional
information/
research
is
needed
to
develop
this
scenario.

5.8
Releases
from
Roadways
to
Streams
­
Aquatic
Life
5.8.1
Available
Data
regarding
wheel­
balancing
weight
losses
associated
with
this
route.

No
information
on
wheel­
balancing
weight
losses
other
than
Root
(
2000)
and
Bodanyi
(
2003)
are
available.
This
variable
is
the
primary
input
for
most
of
the
air,
water,
and
soil
scenarios
assessed,
and
quantitatively
provides
the
mass
of
lead
released
to
the
environment
upon
which
fate
and
transport
processes
act.
Error
in
this
value
proportionally
impacts
predicted
environmental
concentrations
and
exposure
estimates.

Many
data
gaps
exist
for
this
scenario
and
a
series
of
assumptions
were
made
to
fill
them.
The
mechanism
of
physical
abrasion
of
wheel
weights
on
road
surfaces,
rate
of
loss
of
mass
of
intact
weight
by
abrasion,
and
particle
size
of
abraded
lead
is
unknown.
In
the
absence
of
this
information
EPA
assumed
rapid,
complete
abrasion
to
fine
particles.
The
rate
of
abrasion
and
lead
surface
area
(
related
to
particle
size)
significantly
impacts
predicted
environmental
concentrations
and
exposure.
EPA
believes
that
this
assumption
is
conservative
and
would
result
in
estimates
of
environmental
concentrations
and
exposures
higher
than
those
that
would
actually
occur.

The
retention
/
release
of
lead
on
road
surfaces
is
unknown.
This
process
would
impact
how
much
particulate
lead
from
abraded
wheel
weights
is
free
to
enter
air,
water
or
soil.
The
effect
of
surface
type
(
asphalt,
concrete,
etc.)
on
retention
is
also
unknown.
The
retention
of
lead
on
road
surface
significantly
impacts
predicted
environmental
concentrations
and
exposure.
EPA
assumed
100%
of
wheel
weight
lead
is
available
for
transport
(
not
retained
on
road
surface).
EPA
believes
that
this
assumption
is
conservative
and
would
result
in
estimates
of
environmental
concentrations
and
exposures
higher
than
those
that
would
actually
occur.

Partitioning
of
particulate
lead
from
wheel
weight
lead
abrasion
between
air,
water
and
soil
is
unknown.
EPA
assumed
that
100%
of
wheel
weight
lead
either
goes
to
air,
or
water,
or
soil
for
many
scenarios.
­
31­
Amount
of
wheel
weight
lead
on
road
surfaces
removed
per
unit
of
rainfall
is
unknown.
EPA
assumed
100%
of
previously
deposited
lead
is
removed
with
each
rainfall
event.

National
precipitation
data
average
frequency
and
amount
was
not
available
for
this
assessment.
EPA
assumed
8
rain
events
per
year
and
each
rain
removed
100%
deposited
wheel
weight
lead.

Information
on
typical
stormwater
collection
and
conveyance
practices,
and
flow
rates
of
stormwater
receiving
streams
was
not
available
for
this
assessment.
EPA
selected
an
increasing
range
of
receiving
stream
flow
rates
beginning
at
50
cubic
feet
per
second
to
estimate
surface
water
concentrations.

Information
on
the
range,
average
and
distribution
of
chemical
characteristics
of
stormwater
and
surface
waters
(
e.
g.,
pH,
hardness,
dissolved
organic
carbon
(
DOC),
total
suspended
solids
(
TSS),
sulfate,
etc)
on
a
National
basis.
Water
chemistry
has
major
influence
on
limiting
lead
solubility,
but
because
a
conservative
approach
was
taken,
the
assessment
did
not
address
metal
speciation,
and
EPA
estimated
total
lead
concentration.

5.8.2
Method
used
to
calculate/
quantify
the
exposure
estimate
for
this
Route
The
surface
water
concentration
for
total
lead
was
calculated
as
follows:

C
=
L/
Q
C
=
average
concentration
mg/
liter
L
=
loading
mg/
day
Q
=
flow
liters/
day
The
following
assumptions
are
used
in
constructing
the
hypothetical
exposure
scenario:

­
1
mile
roadway
runoff
drains
directly
into
stream
with
flow
of
122
million
liters
per
day
(
default
low
flow
of
50
CFS)

­
stream
loading
and
flow
are
constant
for
the
length
of
the
stream
­
annual
loading
from
wheel­
balancing
weights
is
1.68
kg/
mile
of
road
­
precipitation
does
not
appreciably
add
to
stream
flow
­
deposited
lead
is
completely
washed
off
road
in
each
of
8
annual
rain
events
­
all
lead
is
soluble
­
32­
Table
4.
Estimated
surface
water
concentrations
from
lead
run­
off
Stream
Flow
(
CFS)
Stream
Flow
(
MLD)
Pb
concentration
(
ppb)

50
122
1.7
100
245
8.2
1000
2453
0.82
5000
12268
0.16
10000
24538
0.08
100000
245376
0.01
5.8.3
Conclusions
drawn
from
the
analysis
EPA
has
constructed
a
hypothetical
exposure
scenario
using
available
data
and
information.
There
are
numerous
uncertainties
associated
with
the
exposure
scenario;
the
more
important
assumptions
and
uncertainties
concern
the
source
term,
or
the
amount
of
lead
released
and
available
during
the
use
of
lead
wheel­
balancing
weights
in
the
scenario
evaluated.
There
are
also
important
environmental
variables
impacting
the
fate
of
lead
in
surface
waters
that
can
vary
geographically
(
see
uncertainties
in
this
section
and
the
discussion
of
the
environmental
fate
of
lead).
Rather
than
attempting
to
account
for
these
variables,
the
scenario
used
simplifying
assumptions
that
would
result
in
conservative
estimates
of
lead
concentrations
in
surface
waters.
­
33­
6.0
DATA
GAPS
AND
UNCERTAINTIES
ASSOCIATED
WITH
ENVIRONMENTAL
AND
HUMAN
HEALTH
EXPOSURE
ASSESSMENT
OF
LEAD
WHEEL­
BALANCING
WEIGHTS
Table
5
provides
a
listing
of
the
data
gaps
and
uncertainties
identified
by
USEPA.
Such
data
is
needed
to
provide
an
improved
understanding
of
the
potential
environmental
and
human
health
impacts
associated
with
environmental
releases
from
lead
wheel­
balancing
weights.

Table
5.
Summary
of
Uncertainties
and
Data
Gaps
Table
associated
with
Lead
Wheel­
Balancing
Weight
Exposure
Assessment
Scenario/
data
element
Data
gap
How
the
data
could
be
used
I.
Data
needs
regarding
lead
wheel­
balancing
weights
from
point
of
manufacture
to
point
of
deposition
on
roadways.

Data
on
the
total
mass
of
lead
wheel­
balancing
weights
that
are
lost
to
roadways
throughout
the
USA
per
year.
Updated
information
on
the
number
of
cars
and
trucks
that
travel
US
roadways
per
year,
including
information
on
areas
with
high
or
low
traffic
volumes.
To
develop
relative
loss
rates
for
wheel
weights
from
vehicles
to
estimate
number
of
wheel
weights
lost
per
road
mile.

Updated
information
on
the
mass
of
lead
wheel­
balancing
weights
released
onto
roadways
from
cars
and
trucks
ranging
in
age
from
new
to
near
end­
ofservice
life
and
are
currently
on
roadways.
To
incorporate
the
effect
of
vehicle
age
into
the
estimation
of
wheel­
balancing
weight
loss
to
roads.

Updated
information
on
the
mass
of
lead
wheel­
balancing
weights
released
onto
roadways
from
"
replacement
tires"
on
cars
and
trucks
that
are
currently
on
roadways.
To
incorporate
the
effect
of
the
use
of
replacement
tires
into
the
estimation
of
wheelbalancing
weight
loss
to
roads.
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
34­
Data
on
factors
that
increase
or
decrease
rate
of
loss
of
wheel
weights
from
a
new
or
old
car
or
truck,
or
from
replacement
tires
on
cars
and
trucks,
e.
g.,
climate;
precipitation
events;
speed
of
vehicles;
vehicle
stopping
and
turning;
relative
age
of
car
or
wheels;
reuse
of
wheel
weights.
This
information
would
assist
EPA
in
developing
a
better
understanding
of
whether
there
are
certain
factors
that
should
be
considered
when
assessing
potential
for
loss
of
wheel­
balancing
weights
onto
or
near
roadways.

Additional
field
studies
for
comparison
to
the
field
studies
conducted
by
Root
(
2000)
and
Bodanyi
(
2003)
regarding
the
potential
loss
of
wheelbalancing
weights
from
vehicles
into
the
environment.
Additional
studies
on
potential
releases
to
the
environment
from
lead
wheelbalancing
weight
loss
for
comparison
and
to
establish
ranges
for
use
in
an
exposure
assessment.

II.
Data
needs
regarding
releases
of
lead
from
lead
wheel­
balancing
weights
from
point
of
deposition
on
roadways
to
various
potential
exposure
routes.

Quantitative
information
on
the
ultimate
fate
of
lead
from
lead
wheelbalancing
weights
on
roadways
.
Mechanics
of
physical
abrasion
of
wheel­
balancing
weights
on
road
surfaces,
rate
of
loss
of
mass
of
intact
weight
by
abrasion,
particle
size
of
abraded
lead,
entry
into
air
as
particulates,
deposition
of
particulates
on
soil
and
road
surfaces.
More
accurate
modeling
of
fate
and
transport
of
wheel
weight
derived
lead.
Needed
for
most
air,
water,
and
soil
scenarios.
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
35­
Retention/
release
of
lead
on
road
surfaces.
How
much
particulate
lead
from
abraded
wheel
weights
is
free
to
enter
air,
water
or
soil.
The
effect
of
surface
type
(
asphalt,
concrete,
aggregate,
etc.)
on
retention.
More
accurate
modeling
of
fate
and
transport
of
wheelbalancing
weight
derived
lead
is
needed
for
most
exposure
scenarios.
Retention
of
lead
on
road
surface
significantly
impacts
predicted
environmental
concentrations
and
exposure.

III.
Data
needs
to
assess
particular
exposure
routes
associated
with
potential
releases
from
roadways
to
the
environment
a)
Dust
in
and
near
roadways
from
soil
lead
and
neat
lead
(
soil/
dust
inhalation).
Information
on
the
amount
of
lead
left
on
roadways
from
lead
wheel­
balancing
weights
which
is
released
into
dust
on
and
near
roadways
Input
to
estimation
of
lead
dust
concentration
from
abraded
wheel­
balancing
weights.
Lack
of
this
information
results
in
the
use
of
simplifying
assumptions
which
may
overpredict
or
underpredict
environmental
concentrations
and
exposures.

b)
dust
from
roadways
migrating
to
residential
soil
(
ingestion
of
soils
route
­
(
i.
e.,
soil
to
mouth)).
Information
on
the
amount
of
lead
left
on
roadways
from
lead
wheel­
balancing
weights
which
is
released
into
dust
on
and
near
roadways
Input
to
estimation
of
lead
dust
concentration
from
abraded
wheel­
balancing
weights.

deposition
pattern
of
particulate
lead
abraded
from
wheel
weights
on
roadside
soil.
Input
to
estimation
of
soil
lead
concentration
from
abraded
wheel­
balancing
weights.
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
36­
horizontal
and
vertical
concentration
gradient
of
lead
abraded
from
wheel­
balancing
weights
in
roadside
soil.
Input
to
estimation
of
soil
lead
concentration
from
abraded
wheel­
balancing
weights.

rate
of
loss
of
wheel
weight
lead
in
roadside
soil
and
important
loss
mechanisms
Input
to
estimation
of
soil
lead
concentration
from
abraded
wheel­
balancing
weights.

Residence
time
of
wheel
weight
lead
in
roadside
soil
available
for
exposure
Input
to
estimation
of
soil
lead
concentration
from
abraded
wheel­
balancing
weights.

c)
Dust
migrating
into
residence
via
pathways
a)
and
b)
above
(
i.
e.,
dust
from
road
into
residence,
and
dust
from
soil
into
residence);
and
dust
into
residence
from
residential
soil
via
foot
traffic
into
house
(
inhalation/
ingestion
routes)
(
i.
e.,
ingestion
of
dust
that
has
settled
in
the
home
(
i.
e.,
dust
to
mouth);
and
inhalation
of
airborne
dust
that
has
entered
the
home).
Information
on
the
amount
of
lead
left
on
roadways
from
lead
wheel­
balancing
weights
which
is
released
into
dust
on
and
near
roadways
and
which
transports
into
homes
near
roadways.
Input
to
estimation
of
lead
dust
concentration
in
home
from
releases
from
abraded
wheel­
balancing
weights.

Information
on
the
amount
of
lead
left
on
residential
soil
which
is
released
into
dust.
Input
to
estimation
of
lead
dust
concentration
in
home
from
releases
from
soil.

Information
on
the
amount
of
lead
dust
tracked
into
residence
from
residential
yards
Input
to
estimation
of
lead
dust
in
home
from
releases
from
lead
tracked
into
residence
from
residential
soil.

d)
weights/
particles
swept
up
by
municipal
street
cleaners
and
incinerated
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
incinerator)
Information
on
the
amount
of
lead
left
on
roadways
from
lead
wheel­
balancing
weights
which
is
swept
up
by
municipal
street
cleaners
and
incinerated.
Input
to
estimation
of
releases
from
incinerators
from
wheelbalancing
weights
collected
by
street
cleaners
and
general
population
exposure.

Loading
of
lead
wheelbalancing
weights
in
kilograms
per
year
per
incinerator
As
input
to
air
dispersion
modeling
of
incinerator
emissions.
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
37­
Quantity
of
sweepings
from
street
cleaners
that
goes
to
incinerators
As
input
to
air
dispersion
modeling
of
incinerator
emissions.

Removal
efficiency
of
lead
from
wheel­
balancing
weights
during
incineration
As
input
to
air
dispersion
modeling
of
incinerator
emissions.

Air
emissions
stack
parameters
for
municipal
incinerators.
As
input
to
air
dispersion
modeling
of
incinerator
emissions.

e)
weights/
particles
swept
up
by
municipal
street
cleaners
and
landfilled,
potential
migration
to
groundwater,
and
drinking
water
wells
(
ingestion
of
drinking
water
route);
Information
on
the
amount
of
lead
left
on
roadways
from
lead
wheel­
balancing
weights
which
is
swept
up
by
municipal
street
cleaners
and
landfilled.
Input
to
estimation
of
releases
from
landfills
from
wheelbalancing
weights
collected
by
street
cleaners.

Data
regarding
the
expected
leach
rate
of
lead
from
wheelbalancing
weights
within
municipal
solid
waste
landfills.
To
estimate
potential
general
population
exposure
to
lead
via
ingestion
of
contaminated
groundwater
.

Data
regarding
the
type
of
landfills
that
cities
and
towns
use
for
disposal
of
waste
collected
by
street
cleaning
machines,
including
whether
the
landfills
are
lined
and
have
leachate
collection
systems.
To
estimate
potential
general
population
exposure
to
lead
via
ingestion
of
contaminated
groundwater
.

IV.
Data
needs
to
assess
particular
exposure
routes
associated
with
potential
consumer
exposure
from
reuse
of
lead
wheel­
balancing
weights
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
38­
f)
vapors
from
home
melting
of
used
wheelbalancing
weights
obtained
by
hobbyists
to
cast
objects,
e.
g.,
sinkers,
bullets,
etc(
inhalation
route)
general
practice/
procedure
for
hobby
wheel­
balancing
weight
melting
and
lead
casting
including
frequency
and
duration
of
hobby
activity
Input
into
exposure
estimate.

breathing
zone
lead
concentration
resulting
from
hobby
lead
wheel­
balancing
weight
melting
in
home
melting
pot
Input
into
exposure
estimate.

temperature
range
used
for
lead
melting
Assess
potential
for
lead
fume
generation.

g)
Quantity
of
lead
wheel
balancing­
weights
left
on
cars
collected
and
burned
in
electric
arc
furnaces
(
EAF)
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
furnace).

h)
releases
associated
with
auto
shredder
activities
(
inhalation
route)
(
i.
e.,
inhalation
of
airborne
releases
from
shredder)
Yearly
loading
of
lead
wheel
weights
from
automobiles
sent
to
End­
of­
Life
Vehicle
(
ELV)
reclamation
facilities
in
the
U.
S.:
yearly
lead
loading
to
Automobile
Shredder
(
AS)
operations;
yearly
lead
loading
to
EAF
operations;
Estimation
of
releases
of
lead
to
air
and
input
into
exposure
calculation.

Distribution
of
lead
in
various
waste
streams
associated
with
the
processing
of
ELVs
in
AS
and
EAF
operations
during
automobile
reclamation
activity
Estimation
of
releases
of
lead
to
air
and
input
into
exposure
calculation
Environmental
release
factors
associated
with
each
reclamation
facility
waste
stream
containing
lead
from
lead
wheel
weights.
Estimation
of
releases
of
lead
to
air
and
input
into
exposure
calculation
i)
releases
from
roadways
to
surfacewaters
Amount
of
wheel
weight
lead
on
road
surfaces
removed
per
unit
of
rainfall
Input
into
exposure
calculation.
Needed
to
determine
reasonable
scenario
for
lead
wash­
off
from
road
surface
and
into
stormwater
conveyance
system
.
Scenario/
data
element
Data
gap
How
the
data
could
be
used
­
39­
National
precipitation
data:
frequency
and
amount
Needed
to
determine
reasonable
scenario
for
wheel
weight
lead
wash­
off
from
road
surface
and
into
stormwater
conveyance
system,
and
potential
wheel
weight
lead
concentration
in
stormwater
Information
on
typical
stormwater
collection
and
conveyance
practices,
and
flow
rates
of
stormwater
receiving
streams
Needed
to
determine
reasonable
scenario
for
discharge
of
stormwater
conveyance
system
to
surfacewaters
characterization
of
stormwater
and
surface
waters
(
e.
g.,
pH,
hardness,
DOC,
TSS,
sulfate,
etc)
Needed
to
predict
metal
speciation
if
estimates
beyond
total
lead
are
desired.
Water
chemistry
has
major
influence
on
lead
solubility.
­
40­
7.0
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Lead
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68.
­
43­
Attachment
1
Summary
of
Environmental
Lead
Literature
Search
on
Lead
Wheel­
Balancing
Weights
­
44­
inc.

MEMORANDUM
TO:
Conrad
Flessner
cc:
111126.1000.008
Edward
Hanlon
Richard
Wormell
FROM:
Chris
Greene/
Jim
Buchert/
Mike
Nelson/
Chuck
Peck
DATE:
May
26,
2005
SUBJECT:
Literature
Search
for
Exposure
and
Risk
Assessments
for
Lead
Tire
Weights
Attached
are
the
results
of
the
literature
search
conducted
for
lead
tire
weights
and
associated
exposure/
risk
pathways
and
assessments.
Versar
conducted
literature
searches
in
the
PubMed,
ToxLine,
AGRICOLA,
Science
Direct,
and
DIALOG
databases,
as
well
as
general
Internet
searches
using
the
GOOGLE
search
engine.
Below
is
a
summary
of
Versar's
findings.
Hard
copies
(
along
with
PDF
files
on
CD)
of
the
publications
and
Internet
sites,
along
with
the
summary
of
findings
for
each
document,
are
provided
in
the
following
Attachments:

Attachment
A:
Environmental
lead
literature
search
focusing
on
identification
of
reasonable
exposure
pathways
associated
with
releases
from
lead
tire
weights
into
the
environment.
Attachment
B:
Literature
search
for
lead
tire
weight­
related
information
using
EPA
recommended
websites
listed
in
Technical
Direction.
Attachment
C:
Literature
search
using
references
in
TSCA
petition.
Attachment
D:
Literature
searches
for
lead
exposure
scenarios
on
military
or
civilian
shooting/
trap
ranges
Attachment
E:
European
Union
literature
searches
for
heavy
metals
and
waste
reduction
methods
related
to
motor
vehicles.
Discussion
°
In
general,
the
availability
of
information
pertaining
to
exposure
and/
or
risk
assessments
for
lead
tire
weights
is
very
limited.
Specific
documents
that
focused
on
lead
tire
weights
include:
California
Department
of
Transportation
Environmental
Program
Proposed
Soil
Lead
Management
Criteria
as
Part
of
Caltrans
Highway
Construction
and
Maintenance
(
Document
#
26);
Environmental
Defense,
Ecology
Center,
Clean
Car
Campaign
Getting
the
Lead
Out
­
Impacts
of
and
Alternatives
for
Automotive
Lead
Uses
(
Document
#
27);
Lead
Loading
of
Urban
Streets
by
Motor
Vehicle
Wheel
Weights,
Robert
A.
Root
(
Document
#
29);
and
Lead
Use
in
Ammunition
and
Automotive
Wheel
­
45­
Weights:
An
Examination
of
Lead's
Impact
on
Environmental
and
Human
Health,
the
Alternatives
to
Lead
Use,
and
the
Case
for
a
Voluntary
Phase­
Out,
Ryan
Bodanyi
(
Document
#
48).

°
The
Internet
sites
provided
by
EPA
did
not
provide
information
on
exposure
or
risk
pathways
specifically
for
lead
tire
weights
(
refer
to
Documents
#
1
through
#
9
in
Attachment
B).
They
did
provide
generic
information
on
lead
tire
weights
and
the
toxicity
of
lead.
The
EPA
Internet
sites
did
not
focus
on
lead
tire
weights,
but
instead
provided
information
on
residential
exposure
to
lead,
including
some
limited
information
on
pathways.
The
residential
exposure
was
primarily
the
result
of
home
renovations
and
lead­
based
paint
removal.

°
The
references
cited
in
the
TSCA
petition
(
refer
to
Documents
#
10
through
#
16
in
Attachment
C)
also
did
not
provide
information
on
exposure
or
risk
assessments
for
lead
tire
weights.
The
papers
did
provide
information
regarding
urban
runoff
and
lead
concentrations
in
the
runoff.
The
papers
also
provided
some
information
as
to
the
percentage
vehicular
traffic
played
in
regards
to
lead
in
the
urban
runoff.
However,
there
were
no
specific
references
to
lead
tire
weights,
save
the
Root
(
i.
e.,
Lead
Loading
of
Urban
Streets
by
Motor
Vehicle
Wheel
Weights,
Robert
A.
Root
(
Document
#
29))
and
Bodanyi
papers.

°
Analyses
regarding
previous
EPA
rulemakings
(
e.
g.,
EPA's
TRI
Lead
rule,
the
lead
based
paint
debris
rule,
and
the
hazard
standards
for
lead­
based
paint
and
lead
in
dust
and
soil)
were
covered
in
the
analyses
on
the
Internet
searches
provided
by
EPA
(
refer
to
Attachment
B).
In
particular,
the
lead
in
dust
and
soil
was
covered
in
searches
on
www.
epa.
gov/
opptintr/
lead/
403risk.
html
and
www.
epa.
gov/
opptintr/
lead/
403risksupp.
html,
and
the
lead
based
paint
debris
rule
was
covered
in
searches
at
www.
epa.
gov/
epaoswer/
non­
hw/
muncpl/
landfill/
pb­
paint.
htm.
Exposure
pathway
scenarios
were
identified,
but
they
focused
primarily
on
residential
exposure
from
lead­
based
paint.
Also,
the
exposure
pathway
scenario
analysis
for
EPA's
TRI
lead
rule
could
not
be
located
by
Versar
or
EPA.

°
With
regards
to
EPA
mobile
source
rulemaking
efforts,
the
documents
available
on
the
Internet
did
not
discuss
exposure
and
risk
associated
with
lead.

°
Searches
that
focused
on
lead
exposure
scenarios
on
military
or
civilian
shooting/
trap
ranges
generated
documents
(
refer
to
Documents
#
49
through
#
71
in
Attachment
D)
with
information
on
lead
exposure
and
poisoning,
fate
and
transport
of
lead
from
bullets,
risk
analyses,
estimates
of
lead
on
a
local
and
national
scale
at
shooting/
trap
ranges,
reclamation
of
lead
at
shooting/
trap
ranges,
and
best
management
practices.

°
Analyses
of
other
pertinent
Internet
sites
were
conducted
using
the
GOOGLE
search
engine.
In
particular,
7
searches
were
conducted
using
the
following
key
word
combinations:
­
46­
S
(
exposure,
lead,
wheel,
weight)

S
(
lead,
exposure,
non­
occupational)

S
(
automotive,
lead,
exposure)

S
(
lead,
tire,
weights,
fall,
off)

S
(
lead
tire,
wheel,
weights)

S
(
lead,
exposure,
hobby)

S
(
automotive
shredder
lead)

The
results
are
included
in
Attachment
A.
However,
none
of
the
Internet
links
provided
significant
information
pertaining
to
exposure
or
risk
associated
with
lead
tire
weights.


Based
on
review
of
the
literature
searches
the
most
reasonable
exposure
pathways
for
lead
tire
weights
are
as
follows:

1.
Roadside
­
runoff
­
surface
water
­
aquatic
life
­
fish
consumption
by
anglers
2.
Roadside
­
pulverized
­
dust
in
ambient
air
­
redeposited
near
residences
­
tracked
into
home
­
children
(
dermal,
ingestion,
inhalation)
3.
Roadside
­
picked
up
by
hobbyist
­
melted
in
home
(
to
make
bullets,
lead
sinkers,
lead
soldiers,
etc.)
­
inhalation
by
family
4.
Roadside
­
leach
into
soil
­
groundwater
­
drinking
water
sources
Please
feel
free
to
contact
us
if
you
have
any
comments
or
questions.