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Environmental
Health
Perspectives,
Vol.
106,
No.
2,
February
1998,
pp.
79­
83
Effect
of
Interventions
on
Children's
Blood
Lead
Levels
Steven
R.
Hilts,
1
Susan
E.
Bock,
1
Terry
L.
Oke,
1
Cheryl
L.
Yates,
1
and
Raymond
A.
Copes
2
1
Trail
Lead
Program
Office,
Trail,
British
Columbia,
Canada
2
Department
of
Health
Care
and
Epidemiology,
University
of
British
Columbia,
Vancouver,
British
Columbia,
Canada
 
Introduction
 
Methods
 
Results
 
Discussion
Abstract
Trail,
Canada,
has
been
the
site
of
an
active
lead/
zinc
smelter
for
nearly
a
century.
Since
1991,
the
Trail
Community
Lead
Task
Force
has
carried
out
blood
lead
screening,
case
management,
education
programs
targeted
at
early
childhood
groups
and
the
general
community,
community
dust
abatement,
exposure
pathways
studies,
and
remedial
trials.
From
1989
through
1996,
average
blood
lead
levels
of
children
tested
for
the
first
time
declined
at
an
average
rate
of
0.6
µ
g/
dl/
year,
while
blood
lead
levels
in
Canadian
children
not
living
near
point
sources
appeared
to
be
leveling
off
following
the
phase­
out
of
leaded
gasoline.
Since
there
was
no
concurrent
improvement
in
local
environmental
conditions
during
this
time,
it
is
possible
that
the
continuing
decline
in
Trail
blood
lead
levels
has
been
at
least
partly
due
to
community­
wide
intervention
programs.
One
year
follow­
up
of
children
whose
families
received
in­
home
educational
visits,
as
well
as
assistance
with
home­
based
dust
control
measures,
found
that
these
specific
interventions
produced
average
blood
lead
changes
of
+
0.5­
­
4.0
µ
g/
dl,
with
statistically
significant
declines
in
3
years
out
of
5.
Education
and
dust
control,
particularly
actions
targeted
toward
higher
risk
children,
appear
to
have
served
as
effective
and
appropriate
interim
remedial
measures
while
major
source
control
measures
have
been
implemented
at
the
smelter
site.
Key
words
:
blood
lead,
dust
control,
environmental
lead
exposure,
health
education,
intervention,
smelter
contamination.
Environ
Health
Perspect
106:
79­
83
(
1998).
[
Online
21
January
1998]

http://
ehpnet1.
niehs.
nih.
gov/
docs/
1998/
106p79­
83hilts/
abstract.
html
Address
correspondence
to
S.
R.
Hilts,
Environmental
Coordinator,
Trail
Lead
Program
Office,
843
Rossland
Avenue,
Suite
300,
Trail,
British
Columbia,
V1R
4S8
Canada.

This
work
was
funded
through
grants
to
the
Trail
Community
Lead
Task
Force
by
the
British
Columbia
Ministry
of
Health,
the
British
Columbia
Ministry
of
Environment,
Lands
and
Parks;
Cominco,
Limited;
and
the
City
of
Trail.
The
Rotary
Club
of
Trail,
with
funding
from
the
Task
Force
and
from
the
Environmental
Citizenship
Initiative
(
Environment
Canada),
organized
and
implemented
much
of
the
community
dust
abatement
work
described
herein.
The
authors
are
grateful
to
Nelson
Ames
for
his
comments
on
an
earlier
version
of
this
manuscript.

Received
27
May
1997;
accepted
20
October
1997.

Introduction
During
the
past
two
decades,
numerous
studies
have
found
neurobehavioural
effects
in
children
in
association
with
chronic
low­
level
lead
exposure
(
1,2).
In
1991,
the
U.
S.
Centers
for
Disease
Control
released
a
statement
establishing
15
µ
g/
dl
as
the
level
at
which
individual
children
should
receive
nutritional
and
educational
interventions
and
more
frequent
screening
(
3).
Canadian
guidelines
now
also
suggest
15
µ
g/
dl
as
an
individual
intervention
level
(
4).

Trail,
British
Columbia,
has
been
the
site
of
a
large
active
lead
and
zinc
smelter
for
nearly
a
century.
A
study
conducted
in
Trail
in
1975
found
average
blood
lead
levels
of
22
µ
g/
dl
in
1­
3
year
olds
(
5,6).
A
more
detailed
study
in
1989
found
a
geometric
mean
of
13.1
µ
g/
dl
in
24­
72
month
olds,
with
39.4%
of
the
samples
above
15
µ
g/
dl
(
7).
Recommendations
of
the
study
included
the
implementation
of
a
comprehensive
lead
awareness
and
education
campaign
and
provided
the
impetus
for
creating
the
Trail
Community
Lead
Task
Force.

By
autumn
of
1991,
the
Task
Force
had
established
a
comprehensive
childhood
lead
exposure
prevention
program.
The
program
currently
includes
annual
blood
lead
screening
of
children
aged
6­
60
months,
case
management,
education
programs
targeted
at
early
childhood
groups
and
the
general
community,
community
dust
abatement
programs,
exposure
pathways
studies,
and
intervention
trials.
We
have
previously
reported
on
our
work
involving
indoor
dust
control
trials,
ongoing
soil
treatment
experiments,
and
trends
in
community
blood
lead
levels
from
1991
through
1994
(
8,9).
This
paper
examines
in
more
detail
the
effect
that
community
education,
dust
control,
and
case
management
efforts
appear
to
have
had
on
children's
blood
lead
levels
in
Trail
from
1991
through
1996.
It
is
not
possible
to
precisely
quantify
the
impact
of
these
interventions,
as
the
measures
were
not
withheld
from
matched
control
groups.
Also,
there
is
insufficient
data
to
reliably
establish
the
rate
of
decline
in
blood
lead
levels
that
was
occurring
in
Trail
prior
to
commencement
of
the
intervention
programs.

Methods
Blood
lead
screening
.
Blood
sample
collection
and
analysis
techniques,
as
well
as
the
age
range
of
children
tested,
varied
between
earlier
studies
and
the
current
program.
In
1975,
blood
samples
were
collected
from
children
12­
36
months
of
age
by
the
fingerstick
method
and
analyzed
by
anodic
stripping
voltametry.
In
1989,
fingerstick
samples
from
children
24­
72
months
of
age
were
analyzed
by
a
graphite
furnace
atomic
absorption
spectrometer
with
Zeeman
background
correction
(
10).
In
1990,
there
was
no
general
blood
lead
survey;
only
children
who
had
blood
lead
levels
of
15
µ
g/
dl
or
higher
in
1989
were
tested
as
a
follow­
up.

From
1991
through
1996,
blood
lead
screening
of
children
aged
6­
60
months,
who
lived
in
the
high
exposure
areas
2
and
3
as
shown
in
Figure
1,
was
carried
out
annually.
Each
year
approximately
340
eligible
children
have
been
identified
through
health
unit
immunization
records,
birth
notices,
British
Colmbia
Medical
Services
Plan
data,
local
day
care
centers,
and
kindergarten
lists.
The
participation
rate
for
the
blood
testing
clinics
has
ranged
from
74
to
88%,
with
the
higher
participation
rates
occurring
in
later
years.
Families
voluntarily
attend
the
clinics
at
the
Trail
Lead
Program
office,
where
venous
blood
samples
are
drawn
by
an
experienced
pediatric
phlebotomist
after
obtaining
informed
parental
consent.
Capillary
samples
are
collected
only
in
very
rare
instances
when
venipuncture
fails
or
is
not
acceptable
to
the
parent
or
child.
Blood
samples
are
collected
during
September
each
year,
immediately
after
maximum
summer
exposure
conditions
are
known
to
prevail.

Figure
1
.
Trail
residential
areas.

Blood
samples
are
analyzed
using
a
graphite
furnace
atomic
absorption
spectrometer
with
Zeeman
background
correction
(
10).
The
following
quality
control
(
QC)
procedures
are
used
to
verify
the
accuracy
and
precision
of
the
blood
lead
measurements:
random
split
samples
from
children
are
analyzed
at
both
the
study
laboratory
and
a
QC
laboratory;
replicate
samples
from
adult
volunteers
are
submitted
weekly
to
the
two
labs;
certified
reference
blood
from
the
National
Institute
of
Standards
and
Technology
(
NIST)
is
submitted
weekly
to
the
two
labs;
blood
collection
tubes
and
supplies
are
prescreened
for
contamination
prior
to
the
clinic;
and
all
blood
sample
tracking
data
is
double
entered
into
a
computerized
database
management
system
and
cross­
checked
for
accuracy.
The
annual
blood
lead
clinics
cost
approximately
$
65,000
(
Canadian).

Case
management
.
Blood
lead
results
of
15
µ
g/
dl
or
higher
for
children
20
months
of
age
and
older,
or
greater
than
10
µ
g/
dl
for
children
under
20
months
of
age
trigger
the
family's
inclusion
in
a
case
management
program.
The
case
management
program
began
in
1991
and
currently
consists
of
more
frequent
blood
lead
testing;
in­
home
counseling
on
exposure
reduction
measures
such
as
dust
control,
hygiene,
nutrition,
and
yard
care;
lead
testing
of
bare
ground,
house
dust,
painted
surfaces,
etc.,
to
highlight
areas
needing
immediate
attention;
provision
of
entrance
mats,
sandboxes
with
clean
sand
and
lids,
ground
cover
materials,
and
house
cleaning
supplies
or
services;
and
assistance
with
paint
abatement.
Cleaning
supplies
may
include
mops,
buckets,
detergent,
and
loaned
or
purchased
vacuum
cleaners.
Cleaning
services
include
regular
vacuuming,
wet
wiping,
and
mopping
(
9).
Approximately
$
70,000
(
Canadian)
per
year
is
spent
on
the
case
management
programs.
Education
.
Exposure
reduction
messages
are
delivered
directly
to
young
children
through
semiannual
visits
to
play
schools,
day
care
centers,
and
kindergarten
classes.
Puppets,
a
model
house,
and
a
unique
demonstration
of
the
need
for
careful
hand
washing
are
used
to
teach
young
children
about
hygiene,
nutrition,
and
safe
places
to
play.
Materials
and
financial
contributions
are
also
provided
to
these
groups
to
assist
with
cleaning
and
yard
maintenance
and
to
facilitate
hand
washing
at
their
facilities.

During
the
annual
fall
blood
screening
clinics,
families
are
offered
hand
soap,
a
doormat,
and
various
written
educational
materials
to
reinforce
the
messages
of
good
hygiene,
good
nutrition,
and
minimizing
house
dust.
They
are
also
provided
with
lead
exposure
reduction
guidance
tailored
to
such
factors
as
age
of
their
children
and
their
area
of
residence.
The
Lead
Program's
public
health
nurse
also
meets
with
local
physicians,
makes
presentations
at
prenatal
classes,
visits
mothers
in
the
hospital
maternity
ward,
and
visits
families
in
their
homes.
Trail
area
community
health
nurses
also
include
lead
education
as
part
of
their
regular
well­
baby
visits.

The
Lead
Program's
exposure
reduction
messages,
as
well
as
news
about
program
activities
and
progress,
are
communicated
to
the
general
public
through
distribution
of
a
newsletter
three
times
per
year
to
all
residential
mailing
addresses
in
Trail,
advertisements
in
local
print
and
radio
media,
billboards,
public
displays,
and
quarterly
newsletters
sent
to
parents
through
schools,
play
schools,
and
day
care
centers.

Table
1
provides
a
summary
of
the
wide
variety
of
contact
types,
groups
reached,
and
number
of
contacts
made
in
1991­
1992,
which
was
the
first
year
of
operation
of
education
and
case
management
programs.
Approximately
$
70,000
(
Canadian)
per
year
is
spent
on
education
programs.

Community
dust
abatement
.
Since
1992,
the
following
dust
control
measures
have
been
carried
out
in
the
Trail
area:
annual
spraying
of
dust
suppressant
on
unpaved
alleys
and
parking
surfaces;
greening
of
bare
public
areas
using
turf
or
seed;
covering
of
bare
areas
using
asphalt,
concrete,
or
gravel;
and
more
frequent
sweeping
and
washing
of
paved
streets.
The
Rotary
Club
of
Trail
and
other
public
groups
have
been
instrumental
in
organizing
and
carrying
out
much
of
this
work.
An
average
of
$
17,500
(
Canadian)
has
been
spent
each
year
since
1992,
not
including
the
cost
of
street
cleaning.

Environmental
monitoring
.
Soil
data
were
obtained
from
studies
conducted
in
1977
(
6),
1989
(
7),
and
1992
(
11).
In
each
of
the
studies,
samples
were
collected
from
the
top
2­
3
cm
of
the
soil
profile
and
digested
in
nitric/
perchloric
acids
prior
to
analysis
for
lead.
In
1977,
the
samples
were
not
sieved,
whereas
in
1989
and
1992,
samples
were
passed
through
a
180­
µ
m
screen
before
analysis.
This
report
considers
samples
collected
from
the
same
geographic
areas
in
each
of
the
3
study
years.

Data
for
lead
in
suspended
particulate,
lead
in
dust
fall,
and
number
of
days
with
rain
were
collected
by
the
smelter
company.
Suspended
particulate
was
collected
for
24
hr
every
6
days
by
two
high
volume
air
samplers
located
in
the
immediate
Trail
area.
Dust
fall
was
collected
monthly
in
plastic
jars
located
at
nine
sites
in
the
immediate
Trail
area;
however,
analysis
of
dust
fall
samples
for
lead
did
not
start
until
1991.
The
sampling
equipment,
sampling
sites,
analytical
techniques,
and
quality
control
procedures
for
suspended
particulate
and
dust
fall
data
meet
British
Columbia
Ministry
of
Environment
(
BCMoE)
requirements.
A
quality
control
sampling
station
is
operated
in
Trail
by
the
BCMoE
to
verify
results
obtained
by
the
smelter
company.
Data
from
the
audit
station
were
not
used
in
this
analysis,
as
the
station
did
not
operate
during
part
of
1995
and
1996
due
to
construction
activities
near
the
site.
Precipitation
was
recorded
at
the
smelter
site
as
part
of
the
requirements
of
a
weather
observation
program
operated
by
the
Atmospheric
Environment
Service
(
Environment
Canada).

Data
analysis
.
Analyses
were
conducted
to
examine
the
effects
of
both
the
general
community­
wide
intervention
efforts
and
the
more
specific
one­
on­
one
case
management
efforts.
To
distinguish
between
these
effects,
we
conducted
separate
analyses
of
blood
lead
data
for
children
tested
for
the
first
time
in
each
year
and
for
children
who
received
repeat
testing
subsequent
to
in­
home
case
management
intervention.
The
former
analysis
excluded
children
with
older
siblings
who
had
been
tested
previously,
and
the
latter
analysis
excluded
those
whose
families
had
already
received
case
management
intervention
for
older
siblings.

Frequency
plots
of
blood
and
environmental
lead
data
indicated
that
the
data
were
lognormally
distributed.
Averages
are
expressed
as
geometric
means,
and
hypothesis
testing
and
regression
analyses
were
performed
on
natural
log­
transformed
data.
Age
and
area
adjustment
of
log­
transformed
blood
lead
data
was
performed
using
analysis
of
covariance
(
12)
to
compensate
for
year­
to­
year
differences
in
the
age
and
area
of
residence
distributions
of
participants
where
necessary.

Results
Figure
2
shows
the
trend
in
geometric
mean
blood
lead
levels
for
children
tested
for
the
first
time
in
each
year
from
1989
through
1996
(
there
was
no
blood
lead
survey
in
1990).
The
age
and
area
distributions
of
children
tested
varied
significantly
(
p<
0.01)
from
year
to
year,
so
age
and
area­
adjusted
blood
lead
averages
are
presented.
In
multiple
regression
analysis
with
blood
lead
as
the
dependent
variable,
the
year
of
testing
entered
into
the
regression
model
even
after
adjustment
for
age
and
area
(
see
Table
2).
The
regression
showed
a
declining
trend
of
0.6
µ
g/
dl
(
or
about
5%)
per
year.
Figure
2
.
Age
and
area­
adjusted
geometric
mean
blood
lead
levels
of
children
tested
for
the
first
time,
by
year.
The
regression
line
represents
1989­
1996
means.

Changes
in
local
environmental
lead
levels
and
weather
conditions
were
investigated
to
determine
whether
the
0.6
µ
g/
dl/
year
decline
in
average
blood
lead
levels
in
Trail
might
be
due
to
improvements
in
local
conditions.
Table
3
shows
the
average
soil
lead
levels
in
Trail
from
1977
to
1992.
The
differences
between
years
were
not
statistically
significant,
even
when
paired
analysis
by
postal
codes
was
conducted
on
the
1975
and
1989
data
(
13).
Therefore,
the
decline
in
blood
lead
levels
from
1989
to
1996
is
not
due
to
any
improvement
in
soil
lead
levels.

In
infants
and
toddlers,
where
skeletal
lead
contributes
a
relatively
small
portion
of
total
blood
lead
concentration,
lead
in
blood
is
generally
thought
to
reflect
fairly
recent
exposure
(
i.
e.,
the
past
30
days)
(
14).
Many
of
the
children
tested
annually
in
Trail,
particularly
those
aged
3­
5
years,
have
been
chronically
exposed
to
lead
for
several
years,
and
their
present
blood
lead
levels
are
much
more
dependent
upon
longer
term
past
exposures.
However,
the
year­
to­
year
variability
in
average
blood
lead
levels
in
Trail
might
be
expected
to
correlate
with
exposure
conditions
during
the
summer
months
prior
to
each
annual
blood
testing
clinic.
We
therefore
chose
to
look
at
environmental
and
weather
conditions
during
the
summers
preceding
each
of
the
annual
blood
lead
clinics.

Possible
relationships
between
blood
lead
and
air
lead,
dust
fall
lead,
and
the
number
of
days
without
rainfall
in
the
June
to
August
period
were
examined.
In
multiple
regression,
no
statistically
significant
correlations
were
found
between
average
blood
lead
level
and
air
lead,
dust
fall
lead,
or
number
of
dry
days
for
either
the
whole
summer
period
or
for
any
subset
of
it.
Table
4
shows
that
there
clearly
has
not
been
any
trend
in
August
values
for
ambient
air
lead,
dust
fall
lead,
or
number
of
dry
days
over
the
1989­
1996
period.
Therefore,
the
decline
in
blood
lead
levels
from
1989
to
1996
does
not
appear
to
be
due
to
changes
in
summer
air
lead,
dust
fall
lead,
or
weather
conditions.
Table
5
presents
results
for
children
who
had
elevated
blood
lead
levels
(
15
µ
g/
dl)
and
who
were
tested
again
1
year
after
their
families
received
targeted
interventions
under
the
case
management
program
described
above.
In
each
year,
greater
than
90%
of
eligible
families
accepted
in­
home
counseling
and
assistance
with
exposure
reduction
measures;
thus,
the
number
of
children
with
elevated
blood
lead
levels
who
did
not
receive
interventions
in
each
year
is
very
small.
Therefore,
the
only
available
comparison
is
with
the
children
who
had
elevated
blood
lead
levels
in
1989,
as
interventions
were
not
provided
in
that
year.
Those
children
showed
an
average
increase
of
1.2
µ
g/
dl
when
tested
1
year
later.
The
difference
was
not
statistically
significant.
In
contrast,
when
the
blood
lead
levels
of
counseled
children
have
been
rechecked
1
year
later,
the
average
has
usually
declined
by
statistically
significant
amounts
(
2.3­
4.0
µ
g/
dl).
The
notable
exception
was
from
1995
to
1996,
when
the
blood
lead
levels
of
the
small
number
of
children
who
received
interventions
for
the
first
time
did
not
change
significantly.
There
was
no
significant
relationship
between
age
and
change
in
blood
lead
level
among
the
children
involved.
Therefore,
despite
the
declining
average
age
of
children
enrolled
in
case
management
for
the
first
time,
there
was
no
need
to
age­
adjust
the
blood
lead
data.

Discussion
There
does
not
appear
to
have
been
any
increase
in
the
rate
of
decline
in
blood
lead
levels
of
Trail
children
following
the
introduction
of
interventions
in
late
1991.
As
mentioned
above,
there
is
insufficient
data
to
reliably
establish
the
rate
of
decline
in
blood
lead
levels
that
was
occurring
in
Trail
prior
to
1991.
However,
the
constant
and
gradual
decline
seen
in
blood
lead
levels
of
Trail
children
from
1989
through
1996
roughly
parallels
a
general
worldwide
drop
in
blood
lead
levels
seen
during
the
period
from
about
1976
through
1994
(
15­
19).
In
fact,
the
global
rate
of
decline
has
been
about
0.8­
1.5
µ
g/
dl/
year,
rather
than
the
0.6
µ
g/
dl/
year
seen
in
Trail.
The
global
decline
is
thought
to
be
due
to
such
actions
as
the
phase
out
of
lead
in
gasoline
and
paint,
the
discontinued
use
of
lead
solder
in
food
tins,
and
reductions
in
air
emissions
from
industrial
plants.
In
Canada,
where
leaded
gasoline
was
eliminated
by
1990,
the
Ontario
Blood
Lead
Study
found
that
average
blood
lead
levels
in
children
not
living
near
point
sources
declined
by
about
1.3
µ
g/
dl/
year
from
1984
to
1990
and
then
appeared
to
level
off
(
20).
Therefore,
it
appears
that
the
decline
in
blood
lead
levels
in
Trail
from
1991
through
1996
must
be
at
least
partly
due
to
local
changes.
As
presented
above,
there
was
no
corresponding
improvement
in
local
environmental
conditions
during
this
period.
Therefore,
it
is
possible
that
the
continuing
decline
in
Trail
children's
blood
lead
levels
may
be
at
least
partly
due
to
the
implementation
of
(
and
annual
improvements
in)
community­
wide
intervention
programs.

In
the
1­
year
follow­
up
of
Trail
children
whose
families
received
in­
home
educational
visits,
as
well
as
assistance
with
exposure
reduction
measures,
we
found
that
these
specific
interventions
produced
average
blood
lead
changes
of
+
0.5­
­
4.0
µ
g/
dl,
with
statistically
significant
declines
in
3
years
out
of
5.
A
number
of
other
published
studies
have
also
examined
the
effects
of
educational
efforts
and/
or
assistance
with
measures
such
as
house
cleaning
or
ground
cover
improvement.
A
study
of
in­
home
education
efforts
in
Milwaukee,
Wisconsin,
involved
431
children
up
to
6
years
of
age
with
initial
blood
lead
levels
of
20­
24
µ
g/
dl
(
21).
Advice
on
nutrition,
behavior
change,
and
housekeeping
was
provided
to
families
of
195
children
in
this
group.
The
remaining
236
children
did
not
receive
visits,
either
because
they
were
identified
before
the
education
visits
were
being
offered
or
because
their
families
could
not
be
contacted.
The
mean
decline
in
blood
lead
in
the
group
receiving
visits
was
4
µ
g/
dl.
The
net
difference
in
blood
lead
change
between
groups,
after
adjustment
for
age
and
seasonal
differences,
was
3
µ
g/
dl
(
p
=
0.001).
Another
group
of
28
Milwaukee
children
with
initial
blood
lead
levels
of
25­
40
µ
g/
dl
received
the
same
home
visit
as
in
the
previous
study,
plus
a
visit
from
a
public
health
nurse
(
PHN)
who
conducted
a
child
health
assessment
and
answered
any
questions
about
lead
(
21).
There
was
no
control
group
in
this
study,
as
virtually
all
families
eligible
for
this
program
were
contacted.
The
mean
decline
in
blood
lead
in
this
group
was
6
µ
g/
dl,
which
suggests
that
greater
declines
may
be
achieved
when
initial
blood
lead
levels
are
higher,
or
that
the
second
visit
by
the
PHN
may
have
provided
additional
benefit.

A
study
in
the
former
secondary
lead
smelter
town
of
Granite
City,
Illinois,
involved
78
children
under
6
years
of
age
who
had
initial
blood
lead
levels
greater
than
9
µ
g/
dl
(
22).
The
parents
of
these
children
received
in­
home
counseling
visits
lasting
about
30­
45
minutes.
The
visits
included
advice
on
hand
washing,
nutrition,
housekeeping,
hand­
tomouth
activity,
and
simple
paint
abatement
where
indicated.
There
was
no
control
group.
At
1
year
follow­
up,
the
average
blood
lead
level
had
declined
by
5
µ
g/
dl,
which
is
a
particularly
noteworthy
decrease
considering
that
the
average
initial
blood
lead
level
was
only
14.6
µ
g/
dl.

A
controlled
trial
of
regular
wet
mopping
of
floors,
combined
with
advice
regarding
hand
washing,
housekeeping,
and
lead
"
hot
spot"
avoidance,
found
that
the
average
blood
lead
level
of
the
group
receiving
intervention
fell
from
38.6
µ
g/
dl
to
31.7
µ
g/
dl
(
a
drop
of
6.9
µ
g/
dl),
while
that
of
the
control
group
fell
by
only
0.7
µ
g/
dl
(
23).

A
more
recent
study
found
that
a
combination
of
interior
painted
surface
cleanup,
house
cleanup
with
a
HEPA
(
high
efficiency
particulate
air)
vacuum,
mopping
with
high
phosphate
detergent,
some
carpet
removal,
covering
of
bare
soil
with
sod
or
bark,
provision
of
clean
sand
boxes,
provision
of
household
cleaning
supplies,
and
provision
of
dust
control
information
was
effective
in
preventing
a
seasonal
rise
in
blood
lead
levels
(
24).
A
controlled
trial
of
regular
HEPA
vacuuming
of
interior
floors
in
Trail
failed
to
show
a
clinically
significant
impact
on
either
blood
lead
or
floor
lead
levels
(
8).
However,
an
uncontrolled
follow­
up
study
suggested
that
a
combination
of
regular
HEPA
vacuuming,
wet
mopping,
exposure
reduction
advice,
and
assistance
with
ground
cover
improvement
was
successful
in
reducing
the
summer
seasonal
rise
in
blood
lead
levels
and
in
preventing
the
seasonal
rise
in
floor
lead
loadings
(
9).

Overall,
this
report
suggests
that
comprehensive,
community­
wide
interventions
such
as
education,
greening,
and
other
dust
control
measures
may
have
had
an
impact
on
blood
lead
levels
in
Trail.
However,
the
lack
of
a
control
group
or
adequate
baseline
data
make
it
impossible
to
conclude
that
these
actions
have
had
a
measurable
impact.
On
the
other
hand,
interventions
specifically
targeted
toward
children
with
elevated
blood
lead
levels
do
appear
to
have
an
impact.
Targeted
interventions
such
as
in­
home
counseling
and
assistance
with
home­
based
exposure
reduction
measures
have
been
associated
with
reductions
in
blood
lead
levels
in
Trail,
as
well
as
at
other
sites.
These
targeted
interventions
have
served
as
effective
and
appropriate
interim
measures
in
Trail
while
the
smelter
company
has
been
implementing
critical
source
control
actions,
such
as
the
reduction
of
fugitive
emissions
and
the
construction
of
a
new
state­
of­
the­
art
lead
smelter.
It
is
recommended
that
in­
home
counseling
and
assistance
with
home­
based
exposure
reduction
activities
be
implemented
and
studied
as
preventive
measures
for
infants,
rather
than
focusing
only
on
children
whose
blood
lead
levels
are
already
elevated.

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