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Articles
Accumulation
of
Chlorpyrifos
on
Residential
Surfaces
and
Toys
Accessible
to
Children
Somia
Gurunathan,12
Mark
Robson,1
Natalie
Freeman,1
Brian
Buckley,1
Amit
Roy,1
Roy
Meyer,3
John
Bukowski,
and
Paul
J.
Lioy'
1Environmental
and
Occupational
Health
Sciences
Institute,
Rutgers
University
and
the
University
of
Medicine
and
Dentistry
of
New
Jersey,
Robert
Wood
Johnson
Medical
School,
Piscataway,
NJ
08855
USA;
2Joint
Ph.D.
Program
in
Exposure
Assessment,
Department
of
Environmental
Sciences,
Rutgers,
and
The
UMDNJ-Robert
Wood
Johnson
Medical
School,
Piscataway,
NJ
08855
USA;
3New
Jersey
Department
of
Environmental
Protection,
Pesticide
Control
Program,
Trenton,
NJ
08625
USA;
4University
of
Prince
Edward
Island,
Charlottetown,
Canada
Quantative
emnation
of
major
pathways
and
routes
of
exposure
to
pestiides
is
essential
for
determining
lumuan
risk
The
current
study
was
conducted
in
two
artments
and
examines
the
accumulation
of
the
pesticide
chlorprfos
in
childrens'
toys
after
the
time
or
reentry
a
application.
It
has
been
estblisd
for
the
fint
time
that
a
latile
pesddde
will
accumulate
on
and
in
toy
and
other
sorbat
srfc
in
a
home
via
a
two-phse
physical
process
th
continues
for
at
least
2
wees
posppliation
A
s
n
of
the
abo
for
a
3-6-year-old
chid
yielded
an
esti-
mated
nondietary
total
dose
of
208
pg/kg/day.
Potential
exposure
from
ie
inhalation
pathwa
was
ngigible,
while
dermal
and
nonditary
oral
doses
from
playing
with
tys
contributed
to
39
and
61%
of
the
total
dose
r
If
children
with
high
frequency
moudting
behavior
are
consid-
ered
as
candidates
for
acute
xposure
to
chlorpyrifos
residues,
the
estimated
acute
dose
could
be
as
high
as
356
pglkglday.
Routine
reapplication
of
pesticdes
could
lead
to
onnued
a
mulation
in
toys
and
other
sorbant
surfaces,
e.g.,
pillows,
with
large
sorbant
reservoirs,
which
can
become
a
long-
term
source
of
expos
to
a
child.
Estmates
of
a
child's
nonditary
eposure
to
chorpyrifos
associ-
ated
with
toys
and
other
sorbant
sura
for
a
period
of
1
week
following
application
appear
to
be
of
public
health
concern,
and
studies
of
actual
childhood
exposure
from
this
pathway
are
warranted
in
the
home
environment.
The
above
i
should
be
used
to
dene
current
procedures
for
postapplicaton
reentry
are
sufficent
and
to
eluate
the
need
for
pdures
to
store
frequenty
used
houhold
toys,
pillows,
and
other
sorbant
objects
during
insecticidal
applicatio.
Key
wrd
childrens'
toys,
chlorpyrifo,
nondietay
aeposure
and
dose,
partide
depositon,
peticide
application,
pesticide
residuals,
sivolatile
pesticide,
surface
wipes,
volatilization.
Environ
Heakh
Perspct
106:9-16
(1998).
[Online
9
January
1998]
http:I//ebpnetl.niehsnibgovldocs/1998/106p
9-16gurunathanlabstract.btml
By
far,
principal
pathways
that
cause
chil-
dren
and
adults
in
the
United
States
to
be
exposed
to
pesticides
are
in
the
home.
Studies
have
shown
that
about
90%
of
all
U.S.
households
use
pesticides
(1,2).
It
has
been
estimated
that
U.S.
homemakers
and
homeowners
use
roughly
28.5
million
kg
insecticides
and
126.6
million
kg
antimicro-
bials
annually
(3).
Further,
full-time
home-
makers
and
young
children
spend
up
to
21
hr/day
inside
the
home,
with
another
2.5
hr
inside
other
buildings
or
in
transit
vehicles
(4,5).
Thus,
individuals
spend
up
to
90%
of
their
time
indoors,
which
provides
the
opportunity
for
significant
contact
with
indoor
contaminants
such
as
pesticides.
The
pesticide
chlorpyrifos
(0,
O-diethyl
0-
[3,5,6-trichloro-2-pyridyl]
phosphoroth-
ioate)
has
been
used
more
frequently
in
U.S.
homes
than
other
pesticides
because
it
is
a
broad-spectrum
organophosphate
insecti-
cide
(6).
Chlorpyrifos
gained
popularity
as
a
broad-spectrum
insecticide
in
the
wake
of
the
decreased
availability
of
compounds
such
as
aldrin,
dieldrin,
and
chlordane.
Because
of
the
potential
health
signifi-
cance
of
high
exposures
to
pesticides,
it
is
necessary
to
determine
how
chlorpyrifos,
and
other
pesticides,
distribute
on
and
in
indoor
surfaces
after
application
by
home-
owners,
renters,
and
professional
applica-
tors.
Consumer
uses
of
pesticides
in
and
around
homes
are
of
special
concern
because
homeowners
have
access
to
some
of
the
same
chemicals
as
professional
appli-
cators
and
may
use
and
store
these
chemi-
cals
in
a
manner
that
places
them
and
their
families
at
higher
risk
because
of
the
lack
of
training
or
experience
in
their
applica-
tion.
For
example,
between
1991
and
1992,
the
San
Francisco
Poison
Control
Center
reported
almost
1,000
adverse
health
outcomes
due
to
pesticide
exposure.
Two
hundred
cases
involved
children
who
were
5
years
of
age
or
younger
(3).
Following
an
application,
pesticides
deposited
indoors
can
represent
a
signifi-
cant
source
of
potential
contact
and
expo-
sure
to
young
children
through
non-
dietary
ingestion
and
dermal
absorption
pathways.
Children
are
of
special
concern
for
exposure
because
of
their
frequent
con-
tact
with
surfaces
that
may
contain
pesti-
cides
and
their
display
of
enhanced
hand-
to-mouth
activity,
which
leads
to
ingestion
of
the
pesticides.
From
1985
to
1990,
the
EPA
conducted
the
Non-Occupational
Pesticide
Exposure
Study
(NOPES)
in
Jacksonville,
Florida,
and
Springfield,
Massachusetts,
to
assess
nonoccupational
total
human
exposures
to
32
pesticides
and
pesticide
breakdown
prod-
ucts.
Their
objective
was
to
estimate
the
dis-
tribution
of
nonoccupational
exposures
from
air,
drinking
water,
dermal
contact,
and
food;
however,
air
monitoring
was
the
primary
focus
of
the
study.
Homes
(n
=
216)
were
sampled
for
the
presence
of
32
different
airborne
compounds,
and
airborne
chlorpyrifos
was
measured
in
both
locations.
In
Jacksonville,
chlorpyrifos
was
found
in
100%
of
the
household
indoor
air
(1.
In
addition
to
indoor
air,
insecticides
can
be
found
on
floors
and
other
surfaces
and
may
contribute
significantly
to
the
total
exposure
of
the
general
population.
However,
there
is
a
paucity
of
data
available
for
making
an
accurate
assessment
of
the
relative
importance
of
oral
(nondietary),
dermal,
and
inhalation
exposures
to
house-
hold
pesticides
(8-10).
Address
correspondence
to
P.J.
Lioy,
Environmental
and
Occupational
Health
Sciences
Institute,
Rutgers
University
and
the
University
of
Medicine
and
Dentistry
of
New
Jersey,
Robert
Wood
Johnson
Medical
School,
170
Frelinghuysen
Road,
P.O.
Box
1179,
Piscataway,
NJ
08855-1179
USA.
The
authors
wish
to
thank
Rufus
Edwards,
Stephanie
Hamel,
Richard
Opiekun,
Scott
Petlick,
Karyn
Reed,
Tom
Wainman,
and
Matthew
Wund
for
field
support
and
guidance.
This
research
was
supported
with
funds
provided
by
cooperative
agree-
ment
CR821902
as
a
subcontract
from
the
Research
Triangle
Institute
for
the
National
Human
Exposure
Assessment
Study
and,
in
part,
by
the
New
Jersey
Department
of
Environmental
Protection
Pesticide
Control
Program.
P.J.L.
and
N.F.
are
also
supported
by
an
NIEHS
Center
of
Excellence
contract
(ES-
05022).
All
laboratory
facilities
were
associated
with
the
Exposure
Measurement
and
Assessment
Division,
Environmental
and
Occupational
Health
Sciences
Institute,
and
the
Center
of
Excellence.
This
paper
has
not
gone
through
official
EPA
review
pro-
cedures;
thus,
it
should
not
be
considered
to
have
approval,
and
the
contents
do
not
necessarily
reflect
the
views
or
policies
of
the
EPA.
Received
15
May
1997;
accepted
7
November
1997.
Environmental
Health
Perspectives
*
Volume
106,
Number
1,
January
1998
9
Articles
*
Gurunathan
et
al.
Chlorpyrifos
and
other
pesticides
are
applied
for
termiticidal
treatment
in
crawl-
space
and
slab-type
construction
dwellings.
They
are
also
applied
using
crack
and
crevice
treatment
for
the
control
of
cock-
roaches.
Broadcast
applications,
however,
may
present
the
greatest
potential
for
expo-
sure
in
a
home
because
a
pesticide
is
applied
ubiquitously
on
large
area
surfaces,
e.g.,
car-
peting
(11).
The
technique
is
still
used
fre-
quendy
by
homeowners,
apartment
mainte-
nance
personnel,
and
small
pest
control
operations
in
the
United
States
and
other
countries.
This
paper
evaluates
nondietary
ingestion
and
dermal
contact
associated
with
surfaces
and
children's
toys
after
treatment
of
two
similar
apartments
with
Dursban
(EPA
registration
no.
464-571).
The
formu-
lation
contained
41.5%
chlorpyrifos.
The
measurements
included
concentration
of
chlorpyrifos
in
air,
in
toys,
and
in
dust
in
and
on
smooth
surfaces
(12-14).
The
study
also
documented
the
time-series
distribu-
tion
of
pesticides
in
various
media
to
eluci-
date
deposition
patterns
in
and
on
surfaces
and
to
estimate
nondietary
oral
and
dermal
exposure
of
children
to
chlorpyrifos.
Methods
Sample
collection
strategy.
The
study
reported
here
was
conducted
in
two
apart-
ment
suites
located
at
Rutgers
University,
Piscataway,
New
Jersey,
during
July
1996.
The
two
apartments
had
identical
furnish-
ings
and
layout
and
had
a
living
space
of
approximately
860
ft2.
The
living
room
and
both
bedrooms
were
carpeted
and
linoleum
was
used
on
all
other
floor
surfaces.
The
heating,
ventilation,
and
air-conditioning
unit
(HVAC)
in
the
apartment
was
an
evap-
orator/cooler
system.
The
HVAC
was
self
contained
within
each
apartment
and
was
operated
throughout
the
study
period.
Partial
ventilation
was
used
in
each
apart-
ment
during
the
experiment.
The
windows
were
kept
dosed
during
pesticide
application
and
for
2
hr
after
application.
Following
that
period,
the
windows
were
opened
for
4
hr
and
a
fan
was
operated
near
a
window
dur-
ing
this
time.
Subsequently,
the
windows
were
closed
and
remained
closed
for
the
2-
week
study
period.
The
partial
ventilation
scheme
was
employed
because
it
best
repre-
sents
a
situation
in
which
a
homeowner
applies
the
pesticide
following
label
direc-
tions
and
provides
a
period
of
ventilation
after
pesticide
application.
The
pesticide
formulation
consisted
of
a
40-ml
concentrate
(containing
58%
inert
ingredients)
that
produced
a
0.5%
chlor-
pyrifos
solution
when
added
to
1
gal
water.
Broadcast
insecticide
treatments
were
made
to
the
entire
floor
surface
area
using
a
1-gal
stainless
steel
pump
sprayer
with
a
hollow
cone
nozzle
and
applied
by
a
licensed
pesti-
cide
applicator.
The
application
lasted
5-7
min/room,
and
approximately
2,000
ml
of
the
formulation
was
used
in
each
apart-
ment.
This
quantity
of
pesticide
mixture
yielded
12
g
chlorpyrifos
applied
to
surfaces
in
an
apartment
(15).
The
temperature
and
relative
humidity
were
recorded
for
each
apartment
continu-
ously
over
the
2-week
study
period.
The
temperature
ranged
from
65
to
77°F
±
3°F
standard
deviation
(SD),
and
the
relative
humidity
ranged
from
59
to
79%
±
5%.
Air,
surface,
and
toy
samples
were
taken
as
part
of
the
study
(Table
1).
Based
on
lit-
erature
values
and
a
pilot
investigation
con-
ducted
during
August
1995,
the
time
peri-.
ods
specified
in
Table
1
were
selected
for
sampling
(10,16-22).
Air
samples
were
taken
in
the
living
area.
Surface-wipe
sam-
ples
were
taken
from
the
top
of
a
dresser
(plastic
laminate
top)
located
in
one
of
the
bedrooms.
Figure
1
illustrates
the
sampling
scheme
for
wipe
samples
taken
from
the
dresser
top.
The
boxes
labeled
A
represent-
ed
regions
of
accumulated
chlorpyrifos
deposition
for
the
labeled
periods
of
time.
These
areas
were
sampled
at
the
specified
time
interval,
and
each
was
wiped
only
once
during
the
study.
The
box
labeled
R
represents
a
region
of
repeated
wipe
sam-
pling.
This
area
was
sampled
at
each
post-
application
time
interval.
It
was
used
to
measure
the
deposition
of
pesticide
residues
between
each
sampling
period.
After
the
first
sample
was
taken,
region
R
contained
a
hexane-methanol
mixture
because
this
mixture
was
used
as
a
wetting
agent
for
the
wipe
samples.
This
is
impor-
tant
for
comparisons
with
the
chlorpyrifos
results
obtained
from
the
toys.
The
sam-
pling
scheme
provided
data
to
compare
the
magnitude
of
surface
residues
present
on
areas
wiped
once
(A)
and
areas
wiped
repeatedly
(R).
Plastic
toys
called
Slammers
(Imperial
Toys,
Ltd.,
China)
and
plush
toys
filled
with
polyfill
called
Geoffrey
(Toys
"R"
Us,
Inc.,
Paramus,
NJ)
were
placed
within
pre-
pared
grids
on
the
living
room
floor
1
hr
after
chlorpyrifos
application,
and
one
of
each
toy
was
removed
for
analysis
of
chlor-
pyrifos
uptake
at
8,
24,
72,
168,
and
336
hr
after
application
(for
a
total
of
five
ver-
sions
of
each
toy).
These
items
and
their
time
of
removal
represented
a
situation
in
which
a
toy
was
placed
and
left
in
a
pesti-
cide-treated
room
and
sequentially
removed
after
the
period
of
time
recom-
mended
by
manufacturer
labels
for
safe
reentry.
The
toys
were
not
directly
sprayed
with
the
pesticide.
The
measurement
results
from
the
deposition
of
chlorpyrifos
on
the
toys
were
compared
with
the
R
sur-
face
samples.
Sampling
techniques
and
analytical
methods.
The
indoor
air
samples
were
col-
lected
with
a
low
flow
rate
indoor
air
sam-
pling
impactor
(IASI)
with
a
PMIO
inlet
(to
collect
particles
of
<10
pm
in
diameter)
(12).
The
filter
was
a
rough
cotton
linter
paper
impregnated
with
activated
carbon
and
had
a
thickness
of
0.40
mm.
The
sam-
ples
were
collected
for
a
period
of
12
hr.
The
filters
were
extracted
in
10
ml
toluene
and
were
sonicated
in
an
ultrasonic
bath
(Ultrasonic
Bath
BS-131-6,
60
Hz;
Sonic
Systems,
Inc.,
Newtown,
PA)
for
30
min.
An
aliquot
was
pipetted
into
1.2-ml
amber
glass
auto
sampler
vials
and
subjected
to
gas
chromatography
(GC)
analysis.
The
Lioy-Weisel-Wainman
(LWW)
sam-
pler
(Patent
#RWJ-91-28)
was
employed
to
measure
the
surface
loading
(micrograms
per
square
centimeter)
of
dust
and
pesticides
on
surfaces
(13,14).
The
LWW
sampler
used
a
template
to
mark
a
specific
area
(100
cm2)
for
the
quantitative
collection
of
dust
by
move-
ment
of
a
constant
pressure
block
within
the
template.
A
self-adhesive
gray
silicone
rubber
pad
was
attached
to
the
smooth
side
of
the
block.
The
filter
media
used
were
Empore
Carbon-18
disks
(3M,
Minneapolis,
MN),
which
are
traditionally
used
for
analysis
of
waste
water.
Tests
demonstrated
99-117%
recoveries
for
chlorpyrifos
at
three
spiking
levels.
Prior
to
sampling,
the
filter
was
immersed
in
methanol
for
approximately
2
sec
and
was
followed
by
immersion
in
hexane
for
the
same
amount
of
time.
Care
was
taken
to
shake
off
excess
solvent
against
the
sides
of
the
solvent
retainer
(an
aluminum
weighing
dish,
for
example).
The
filter
was
placed
on
::.
bA
i
t£
hr
*
.4hrA.
1.
.:
WhrA.
Figure
1.
Chlorpyrifos
residual
sampling
grid
for
a
dresser
top
during
a
1-336
hr
period
after
applica-
tion.
Abbreviations:
A,
surface
residues
from
sin-
gle
wipes;
R,
surface
residues
from
multiple
wipes.
Volume
106,
Number
1,
January
1998
*
Environmental
Health
Perspectives
Table
1.
Sampling
times
and
solvents
for
sample
media
Sample
type
Sampling
times
after
application
(hr)
Extraction
solvent
Toys
8,24,72,
168,336
Hexane
Air
12,
36,48,60,72,
168,
336
Toluene
Surface
4,8,12,24,36,48,60,72,168,336
Hexane
10
Articles
*
Accumulation
of
chlorpyrifos
in
childrens'
toys
the
rubber
pad,
and
the
sampling
block
with
the
filter
were
moved
back
and
forth
five
times
across
the
length
of
the
template.
A
total
surface
area
of
100
cm2
was
wiped
using
the
LWW
sampler
as
a
template.
The
filters
were
extracted
with
5
ml
hexane
(Optima
grade,
Fisher
Scientific,
Norcross,
GA)
and
sonicated
in
an
ultrasonic
bath
for
30
min.
The
extract
was
split
into
two
aliquots
per
wipe
sample.
An
aliquot
was
pipetted
into
1.2-ml
amber
glass
auto
sampler
vials
and
subjected
to
GC
analysis.
The
toys
were
weighed
prior
to
being
placed
in
the
rooms.
The
plastic
toys
were
extracted
in
20
ml
hexane
and
the
plush
toys
were
extracted
in
180
ml
hexane.
Both
extracts
were
sonicated
for
30
min.
Following
sonication,
the
extract
from
the
plush
toys
was
subjected
to
rotary
evapora-
tion
(Buchi
Rotavapor
R-114,
Brinkmann
Instruments,
Inc.,
Westbury,
NY).
The
extract
was
evaporated
to
dryness
and
placed
in
5
ml
hexane.
An
aliquot
was
pipetted
into
1.2-ml
amber
glass
auto
sam-
pler
vials
and
subjected
to
GC
analysis.
All
sample
aliquots
were
kept
frozen
at
-1
5C
until
analysis
by
GC.
Capillary
gas
chromatography
with
an
electron
capture
detector
(GC/ECD)
was
used
to
detect
chlorpyrifos
in
the
sample
extracts.
A
Hewlett-Packard
Gas
Chromatograph
5860
Series
II
(Hewlett-Packard,
Wilmington,
DE)
equipped
with
an
HP
Nickel
63
Electron
Capture
Detector
and
an
Autosampler
Injector
7673
was
used
to
measure
the
concentration
of
chlorpyrifos
in
all
samples.
Quantification
was
per-
formed
using
HP
ChemStation
chro-
matography
software
(Hewlett-Packard).
A
split/splitless
injector
was
held
at
2000C,
and
a
30-m
(0.32
mm
inner
diameter
DB-
1701)
fused
silica
capillary
column,
0.25
pm
film
thickness
(J
&
W
Scientific,
U
41
U.
0a
Folsom,
CA)
wa
from
330C
(hel
30°C/min,
from
and
held
at
the
for
15
min.
Th
held
at
3000C.
flow
rate
was
1.'
of
the
make-uF
ml/min.
The
inj
ples
was
1
pl.
Sc
with
every
run
s
sis
was
complet
and
a
5%
relati
was
considered
cates.
Chlorpyril
by
making
a
sto
by
dissolving
25
dard
in
25
ml
1
serially
diluted
tions
containing
0.1,
0.3,
0.5,
a
curve
was
gene]
response
against
regression
equat
cide
determinati
Results
Chlorpyrifos
co
the
A
surfaces
peaked
36
hr
po
Subsequently,
td
as
the
chlorpy
volatilized
from
repeat
wipe
san
decreased
slightl
began
to
increa
concentration
o
was
equal
in
m
residues
(region
than
72
hr,
and
than
region
A
at
cation.
The
vapc
reported
to
be
1
60
50
40
30
20
10
5s
temperature
programmed
which
makes
it
a
semivolatile
organic
com-
Id
for
1
min)
to
163°C
at
pound.
Semivolatiles
can
partition
between
163
to
253°C
at
5°C/min,
the
vapor
phase
and
condensed
phase;
thus,
final
temperature
of
2530C
a
fraction
of
chlorpyrifos
in
the
deposited
e
detector
temperature
was
dust
will
be
released
into
the
gas
phase
and
The
carrier
gas
(helium)
a
fraction
will
remain
sorbed
to
the
deposit-
5
ml/min
and
the
flow
rate
ed
particles
(23).
This
contradicts
the
com-
gas
(nitrogen)
was
30.7
monly
accepted
paradigm
of
pesticides
jection
volume
for
all
sam-
being
only
a
residue.
)lvent
blanks
were
included
The
two-phase
process
is
illustrated
in
;et.
Duplicate
sample
analy-
Figure
2.
Chlorpyrifos
is
first
distributed
in
:ed
on
every
tenth
sample,
the
particle
phase
(Phase
1)
immediately
ve
SD
in
the
concentration
following
application.
Then,
over
time,
acceptable
between
dupli-
chlorpyrifos
gradually
volatilizes
(as
shown
fos
standards
were
prepared
by
the
decrease
in
the
region
A
values)
into
tck
solution
of
1,000
pg/ml
the
room
(Phase
2).
Subsequently,
the
j
mg
of
the
reference
stan-
vapor
can
be
sorbed
to
an
activated
surface,
hexane.
This
solution
was
such
as
on
the
dresser
(Region
R)
that
had
to
produce
standard
solu-
been
wiped
repeatedly
with
the
chlorpyrifos
at
0.04,
0.08,
hexane-methanol
mixture.
The
volatiliza-
nd
1
pg/ml.
A
calibration
tion
process
also
is
supported
by
data
col-
rated
by
plotting
the
area
lected
in
a
study
conducted
by
Bukowski
et
the
amount.
The
resulting
al.
(15),
in
which
they
used
experimental
tion
was
used
for
all
pesti-
conditions
similar
to
those
described
in
the
ions.
methods
section,
except
that
the
apartment
windows
were
kept
closed
throughout
their
study.
A
passive
dosimeter
employed
dur-
)ncentrations
measured
on
ing
that
study
obtained
time-weighed
aver-
presented
in
Figure
2,
age
inert
volatile
organic
compound
stapplication
at
43
ng/cm2.
(VOC)
measurements
during
the
24-hr
se
levels
decayed
with
time
period
following
the
application.
The
mea-
rifos
either
degraded
or
sured
levels
peaked
at
12
hr
after
applica-
the
surface.
In
contrast,
the
tion,
which
was
considerably
later
than
nples
taken
from
region
R
would
be
predicted
by
EPA
reentry
models
Iy
after
the
36-hr
peak,
but
(2-4
hr)
(24).
Such
(re)volatilization
into
a
tse
again
after
72
hr.
The
room
would
occur
for
the semivolatile
f
chlorpyrifos
in
region
R
chlorpyrifos,
except
at
a
slower
rate
than
iagnitude
to
accumulated
would
be
expected
for
the
VOCs.
A)
at
sampling
times
less
Once
the
chlorpyrifos
is
in
the
gas
phase,
was
at
least
twofold
higher
it
can
diffuse
into
a
medium
possessing
sorp-
168
and
336
hr
after
appli-
tive
properties,
which
should
be
the
case
for
Dr
pressure
of
chlorpyrifos
is
the
two
different
types
of
toys
placed
on
the
.87
x
10-5
mm
Hg
at
20°C,
floor
after
pesticide
application.
When
the
time
course
of
chlorpyrifos
residual
accumu-
lation
was
examined
in
each
type
of
toy,
it
was
observed
that
the
pesticide
did
sorb
to
the
plastic
and
the
felt
toys
(Fig.
3),
with
both
showing
significant
increases
in
chlor-
pyrifos
levels.
The
levels
on
the
plastic
toys
increased
rapidly,
while
the
felt
toys
showed
slower
but
sustained
increases
in
chlorpyrifos
levels
over
the
2-week
sampling
period.
The
accumulation
of
chlorpyrifos
on
toys
was
analogous
to
sorption
of
chlorpyrifos
on
the
hexane-methanol
mixture-extracted
dresser
surface.
The
result
implies
that
toys,
and
especially
felt
toys,
can
serve
as
major
sinks
and
then
as
reservoirs
for
partide-bound
and
Z50
30
350
vapor
phase-bound
pesticide
residues.
To
compare
the
deposition
on
the
toys
with
other
surfaces,
the
surface
area
of
the
Figure
2.
Chlorpyrifos
surface
residues
sampled
from
dresser
tops
post
ap
two
sampling
strategies.
Wipes
for
R
were
hexane-methanol-extractable
i
deposition,
and
Phase
2
is
dominated
by
volatilization.
)plication
in
two
apartments
for
toys
was
measured
prior
to
placement
in
wipes.
Phase
1
is
dominated
by
the
apartments;
this
showed
that
the
sur-
face
concentration
of
the
plastic
toys
Environmental
Health
Perspectives
*
Volume
106,
Number
1,
January
1998
50
100
150
2W
Time
postapplication
(hr)
1
1
Articles
*
Gurunathan
et
al.
20.000
'-
f~
M
InplastictoyApti
e
.-
-a
18,000
MIn
piastic
toy,Aptil
C
18,000
I!iK
OnfeittoyApti L-.
.
-5
18,0A0
M
Onfekttoy,Apti
-l
--'d
-
r._
,@
14,000
t
e
12,000
"1-
8,000
~4,000
fi
2,0000
8
24
72
168
336
Sampling
time
postapplication
(hr)
Figure
3.
Accumulation
of
chlorpyrifos
residues
in
plastic
and
on
felt
toys
in
two
apartments
(Apt
and
Apt
11).
14,000
E
12,00
loo
eix
o
8,ot
0,
40
20C
8
24
72
168
336
Time
postapplication
(hr)
Figure
4.
Chlorpyrifos
surface
loading
on
plastic
toys
in
two
apartments.
increased
with
time
and
peaked
at
1
week
after
application
on
an
average
of
11,503
ng/cm2
(Fig.
4).
The
chlorpyrifos
levels
on
the
toys
were
two
orders
of
magnitude
greater
than
the
loadings
(nanograms
per
square
centimeter)
found
on
the
surface
of
the
dresser.
These
results
demonstrate
that
there
are
numerous
sorptive
sites
for
the
pesticide
to
be
adsorbed
and
absorbed
by
the
polyethylene
toy
(Slammer).
The
wipes
taken
from
the
dresser
were
representative
of
the
fraction
of
chlorpyrifos
adsorbed
by
hexane-methanol
on
or
below
the
surface.
Simulation
of
two-phase
process
of
deposition
and
volatilization.
On
review
of
the
data
presented
in
Figure
2,
the
initial
deposition
rate
of
chlorpyrifos
after
appli-
cation
and
the
subsequent
volatilization
rate
of
chlorpyrifos
were
estimated
using
a
first
order
model
described
by
the
equation
50
45
03
C
=
S
0*
I.
0
U.
S
U
(4
40
35
30
25
20
15
10
5
o
0
50
100
150
200
250
300
350
400
lime
postapplication
(hr)
Figure
5.
Simulation
of
surface
loading
of
semivolatile
organic
compounds-chlorpyrifos
deposition
and
volatilization
over
a
2-week
period.
Phase
1
is
dominated
by
deposition,
and
Phase
2
is
dominated
by
volatilization.
dPkC
kP
dt
2
x
'
(1)
where
P
=
pesticide
amount
on
surface
(grams),
k,
=
deposition
rate
constant
(grams
per
hour),
C
=
concentration
in
air
(grams
per
cubic
meter),
A
=
area
of
surface
(square
meters),
and
k2
=
volatilization
rate
constant
from
surfaces
(grams
per
hour).
The
equation
was
solved
using
Simusolv
software
(Dow
Chemical
Corporation,
Midland,
MI),
and
k1
and
k2
were
estimat-
ed
using
maximum
likelihood
with
a
con-
stant
variance
error
model.
The
indoor
air
concentrations
used
to
estimate
k,
and
k2
were
obtained
by
linear
interpolation
of
the
concentrations
measured
in
the
apartments.
The
actual
pesticide
profile
in
air
was
not
modeled
because
our
data
set
suggests
that
the
rate
of
volatilization
is
dependent
on
additional
factors
such
as
temperature.
The
deposition
rate
(kl)
was
estimated
to
be
7.3
g/hr
and
the
volatilization
rate
(k2)
was
esti-
mated
by
the
model
to
be
0.1
1
g/hr
for
the
dresser
surface
(plastic
laminate).
The
resul-
tant
surface
loading
profile
for
chlorpyrifos
is
shown
in
Figure
5.
The
first
order
model
presented
here
provides
a
rough
approxima-
tion
of
the
magnitude
of
deposition
and
secondary
volatilization.
The
latter
process
leads
to
accumulation
on
artificially
(region
R)
and
naturally
activated
surfaces
or
sor-
bant
surfaces.
The
effect
of
temperature
is
evident
in
Figure
6
from
the
similarity
of
the
measured
chlorpyrifos
air
concentra-
tion-time
profile
and
the
temperature-time
profile.
The
air
concentration
in
both
rooms
increased
during
the
day
and
decreased
at
night.
Unfortunately,
the
pre-
sent
data
are
too
sparse
to
adequately
char-
acterize
the
temperature
effect,
and
addi-
tional
experiments
are
planned.
Exposure
and
dose
estimates.
An
estima-
tion
of
nondietary
exposure
was
completed
for
a
3-6-year-old
child
playing
in
a
room
1
week
after
a
broadcast
application
of
chlor-
pyrifos
for
inhalation,
dermal,
and
nondi-
etary
ingestion.
The
exposure
assessment
presented
here
is
derived
from
chlorpyrifos
concentrations
on
laminated
dresser
tops
and
toys
(plastics
and
plush)
1
week
after
pesticide
application.
Multiple
surfaces
are
present
in
the
environment
such
as
table
tops,
mattresses,
pillows,
and
other
plush
surfaces.
Our
exposure
scenario
is
only
directed
at
contact
with
surfaces,
thus
pre-
senting
the
potential
dose
estimates
to
a
child
in
contact
with
the
dresser
tops
and
toys
upon
entering
the
environment
1
week
after
pesticide
application.
The
plush
toy
data
is
used
to
represent
contact
with
a
soft
toy
and
other
plush
surfaces.
We
have
not
included
daily
contacts
with
surfaces
for
the
7
days
immediately
after
application.
Obviously,
if
the
child's
contact
with
sur-
faces
during
that
period
is
taken
into
con-
sideration,
the
potential
dose
estimates
would
be
higher
for
the
dresser
or
similar
surfaces.
We
assumed
that
each
time
the
child
touched
the
dresser
top
or
a
toy,
he/she
was
able
to
extract
the
same
amount
of
chlorpyrifos
residue
with
each
successive
Volume
106,
Number
1,
January
1998
*
Environmental
Health
Perspectives
12
Articles
*
Accumulation
of
chlorpyrifos
in
childrens'
toys
" | | l *w*w
~~~~~~~~~~~~~Temperature,
Apt
11
a
5
74
_1z
04
72
C
70
U
EC
a2
__
66
0
50
100
150
200
250
300
350
lime
postapplication
(hr)
Figure
6.
Profile
of
indoor
air
levels
of
chlorpyrifos
and
associated
temperature
profile
for
two
apartments
(Apt
and
Apt
1I).
Table
2.
Estimated
nondietary
total
chlorpyrifos
dose
for
a
child
(3-6
years
old)
living
and
playing
at
home
1
week
after
application
Route
of
Air
Surface
Plastic
toy
Plush
toy
Dose/route
Percent
of
exposure
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
total
dose
Inhalation
1.6
-
-
-
1.6
Negligible
Dermal
-
9.2
69
1.8
80
39%
Oral
-
21
44
61
126
61%
The
human
no
observable
effect
level
=
30
pg/kg/day
(42).
Table
3.
Estimated
low
nondietary
chlorpyrifos
dose
for
a
child
(3-6
years
old)
living
and
playing
at
home
1
week
after
application
Route
of
Surface
Plastic
toy
Plush
toy
Dose/route
Percent
of
exposure
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
total
dose
Dermal
3.18a
23a
0.61"a
27
42%
Oral
6.2b
13b
18b
37
58%
a0ermal
absorption
assumed
to
be
1%.
bOral
absorption
assumed
to
be
30%.
Table
4.
Estimated
high
nondietary
chlorpyrifos
dose
for
a
child
(3-6
years
old)
due
to
frequent
hand
to
mouth
and/or
surface
activity
at
home
1
week
after
application
Route
of
Surface
Plastic
toy
Plush
toy
Dose/route
Percent
of
exposure
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
(pg/kg/day)
total
dose
Dermal
34a
69
1.8
105
29%
Oral
146b
44
61
251
71%
aDerived
from
observational
data
for
hand-surface
touches
of
366
times/h
bDerived
from
observational
data
for
hand-mouth
touches
of
70
times/hr
contact.
This
is
a
reasonable
assumption
because
there
are
1)
numerous
surfaces
pre-
sent
in
the
environment,
2)
multiple
areas
for
contact
on
the
same
surface
or
toy,
and
3)
children
come
into
contact
with
multiple
surfaces
during
the
day.
Other
assumptions
made
to
calculate
potential
dose
indude
1)
inhalation
rate
=
12
m3/day
(25);
2)
body
weight
=
20
kg
(25);
3)
surface
area
of
both
hands
-
400
cm2
(200
cm2
for
area
of
fin-
gers);
4)
3%
dermal
absorption
of
chlor-
pyrifos
(see
Table
2)
(26)
and
1%
dermal
absorption
(Table
3);
5)
100%
absorption
through
inhalation
and
oral
pathways
(default
assumption)
(Table
2,
Table
4)
and
30%
oral
and
1%
dermal
absorption
(Table
3);
6)
75%
of
residues
transferred
from
sur-
face
to
hand
(27);
7)
100%
transfer
of
residues
from
toy
to
hand,
and
10
plastic
toys'
and
3
plush
toys'
surfaces
contacted
with
once
a
day;
and
8)
surface
area
of
a
plastic
toy
=
7.73
cm2
and
surface
area
of
a
plush
object
=
396
cm2.
The
estimated
absorbed
inhalation
dose,
a
product
of
air
concentration,
inhalation
rate,
and
percent
absorbed,
divided
by
body
weight
was
1.6
pg/kg/day
at
1
week
after
application
(Table
2).
The
dermal
dose
(based
on.touching
a
flat
surface,
a
product
of
surface
concentration,
the
percent
transferred
and
absorbed,
the
surface
area
of
the
hand,
and
the
frequency
of
hand
to
smooth
surface
touches,
divided
by
body
weight)
was
esti-
mated
to
be
9.2
pg/kg/day.
The
number
of
hand
to
surface
touches
was
derived
from
direct
observations
based
on
8
hr
activity
per
day
and
was
obtained
by
videotaping
young
children
(28).
An
absorbed
dermal
dose
derived
from
playing
with
a
hard
plastic
toy,
a
product
of
concentration
on
the
toy
surface,
percent
transferred
and
absorbed
(3%/case),
surface
area
of
the
hand,
and
the
number
of
toys
played
with
once
a
day,
divided
by
body
weight,
was
estimated
to
be
69
pglkg/day.
Similarly
an
absorbed
dose
derived
from
play-
ing
with
a
plush
object
was
estimated
to
be
1.8
pg/kg/day.
The
nondietary
absorbed
oral
dose
associated
with
touching
a
surface
fol-
lowed
by
insertion
of
the
hand
into
the
mouth,
a
product
of
surface
concentration,
the
percent
absorbed,
the
surface
area
of
a
child's
fingers,
and
hand
to
mouth
touches,
divided
by
body
weight,
was
21
pg/kg/day.
The
frequency
of
hand
to
mouth
touches
was
also
derived
from
direct
video
observational
data
(28).
The
oral
dose
(100%/case)
associ-
ated
with
inserting
a
toy
into
the
mouth
and
chewing
on
the
material,
a
product
of
con-
centration
on
the
toy
surface,
percent
sorbed
onto
the
area
of
the
toy
in
contact
with
the
child,
and
the
number
of
times
the
toy
is
played
with
once
a
day,
divided
by
body
weight,
was
estimated
to
be
44
g/kg/day
for
the
plastic
toy
and
61
p/kg/day
for
the
plush
object.
A
summation
of
the
above
for
a
3-6-
year-old
child
yielded
an
estimated
nondi-
etary
total
dose
of
208
pg/kg/day
(Table
2).
Potential
exposure
from
the
inhalation
path-
way
was
negligible,
while
dermal
and
nondi-
etary
oral
doses
from
playing
with
toys
con-
tributed
to
39
and
61%
of
the
total
dose,
respectively.
If
children
with
high
frequency
mouthing
behavior
are
considered
as
candi-
dates
for
acute
exposure
to
chlorpyrifos
residues,
the
estimated
acute
dose
could
be
as
high
as
356
pglkg/day
(Table
4).
This
calcu-
lation
employs
the
same
values
for
all
other
variables
used
to
calculate
Table
2.
The
EPA
has
suggested
that
3%
dermal
absorption
of
chlorpyrifos
may
be
high.
Similarly,
the
assumption
of
100%
absorp-
tion
through
the
oral
pathway
may
also
be
high.
This
calculation
was
presented
to
provide
a
direct
comparison
with
the
dose
calculated
in
previous
work
performed
by
Fenske
et
al.
(10).
Table
3
illustrates
the
potential
nondietary
doses
obtained
when
a
1%
dermal
absorption
and
30%
oral
absorption
are
used
in
the
calculation.
With
the
latter
assumptions,
the
total
nondietary
dose
estimate
was
64
pg/kg/day.
In
either
case,
however,
results
suggest
that
it
is
plausible
for
children
to
accumulate
Environmental
Health
Perspectives
*
Volume
106,
Number
1,
January
1998
13
Articles
*
Gurunathan
et
al.
body
burdens
of
pesticides
in
a
residential
setting
where
pesticides
are
routinely
used
to
control
insects.
Discussion
Chlorpyrifos
deposited
on
and
in
toys
and
other
absorbent
surfaces
following
a
typical
broadcast
application
and
reentry
period
were
found
at
levels
that
could
yield
substan-
tial
doses
to
a
child
playing
in
the
treated
res-
idence.
Chlorpyrifos
or
other
semivolatile
pesticides
are
of
special
interest
because
the
analyses
of
the
above
data
show
that
a
signifi-
cant
fraction
of
such
compounds
can
be
dis-
tributed
to
surfaces
available
to
children
over
a
2-week
period.
The
modeling
analyses
indicate
that
deposition
occurs
by
both
the
gas
and
particle
phase
processes.
The
vapor
pressure
of
chlorpyrifos
and
the
temperature
of
the
ambient
environment
appear
to
deter-
mine
the
distribution
of
the
material
between
the
gas
phase
and
the
partide
phase,
and
the
vapor
phase
can
deposit
in
or
on
sur-
faces
by
absorption
or
adsorption,
respective-
ly
(23).
The
application
of
the
pesticide
is
followed
by
a
period
of
equilibrium
between
the
particle
and
vapor
phases.
The
results
indicate
that
after
a
period
of
time,
chlor-
pyrifos
is
released
from
the
partides
into
the
ambient
air
of
an
apartment
(residence).
This
vapor
is
sorbed
onto
available
surfaces
such
as
polyethylene
toys
and
our
artificially
activated
plastic
laminate
dresser
top,
a
phe-
nomenon
previously
unaccounted
for
in
esti-
mates
of
a
child's
exposure
and
risk
to
pesti-
cides.
The
pestcide
on
the
laminated
dresser
top
displayed
enhanced
deposition
on
previ-
ously
sampled
areas
because
the
hexane-methanol
mixture
provided
sorptive
sites
for
chlorpyrifos
vapor
deposition.
The
phenomenon
indicates
that
a
variety
of
com-
mon
household
surfaces,
which
are
filled
with
foam,
e.g.,
toys,
pillows,
and
bedding,
can
sorb
chlorpyrifos
as
a
result
of
this
two-
stage
process.
Camann
et
al.
(29)
reported
that
polyurethane
foam
(PUF)
in
furniture,
pillows,
and
mattresses
could
be
contributing
sources
to
indoor
air
levels
of
chlordane,
chlorpyrifos,
dieldrin,
heptachlor,
and
pen-
tachlorophenol.
PUF
has
been
used
for
air
sampling
of
pesticides
(30).
The
pesticide
accumulation
in
toys,
specifically
soft
plush
toys,
as
shown
by
this
study
indicates
that
they
behave
in
an
analogous
manner
to
PUF
and
may
be
a
source
of
pesticides
that
leads
to
exposure
in
young
children.
The
toys
can
serve
as
reservoirs
of
accumulated
chlorpyri-
fos
levels
(adsorbed
and
absorbed)
over
the
2-week
period.
The
bioaccessibility
of
the
pesticide
sequestered
in
the
toy
was
not
addressed
in
this
study
and
is
an
improtant
follow-up
experiment.
The
population
at
greatest
risk
of
expo-
sure
to
pesticides
found
indoors
in
various
media
are
infants
and
toddlers
(0.5-5
years
of
age);
this
appears
to
be
a
result
of
mouthing
of
hands,
which
touch
objects
like
toys
and
pillows.
The
exposure
assess-
ment
completed
to
examine
the
potential
significance
of
nondietary
pathways
calcu-
lated
doses
1
week
following
application.
In
the
reported experiments,
the
applica-
tion
was
performed
by
a
licensed
applica-
tor,
and
the
ventilation
condition
was
derived
from
the
recommendation
on
the
product
label
(both
designed
to
minimize
distribution
of
the
pesticide).
If
the
broad-
cast
mode
of
application
were
replaced
by
a
crack
and
crevice
protocol,
the
potential
exposure
would
be
further
reduced,
but
it
would
not
be
eliminated.
Some
of
the
uncertainty
associated
with
our
exposure
estimates
was
removed
by
the
use
of
actual
time-activity
data.
The
direct
counts
for
hand
to
surface
and
hand
to
mouth
touches
enable
a
more
realistic
approximation
of
potential
exposure
of
a
child
to
pesticide
residues.
It
has
been
sug-
gested
that
a
3%
dermal
absorption
rate
for
chlorpyrifos
might
be
low
(9)l;
however,
oth-
ers
have
suggested
that
these
values
are
high.
The
EPA
used
a
1%
absorption
rate
in
the
analyses
of
exposure
presented
in
Table
3,
based
on
a
study
conducted
by
Nolan
et
al.
(26).
However,
the
hands
of
young
children
are
often
moist
with
either
saliva
or
sweat,
and
it
has
been
reported
that
saliva-wetted
hands
transferred
about
100
times
more
dried
pesticide
residues
from
treated
carpet
than
dry
hands
(31).
Thus,
young
children
may
transfer
and
absorb
even
higher
amounts
of
pesticides
when
their
sticky,
sali-
va-wetted
hands
contact
contaminated
sur-
faces,
e.g.,
toys,
plush
objects.
In
calculating
the
potential
dermal
dose
from
the
child's
playing
with
the
toy,
it
was
assumed
that
the
child
did
not
wash
his/her
hands
over
an
8-hr
period.
The
literature
indicates
that
washing
skin
with
soap
and
water
does
not
completely
remove
pesti-
cides
(32).
Further,
in
the
same
study
it
was
reported
that
skin
penetration
increased
with
residence
time
of
the
pesti-
cide
on
skin
for
most
compounds.
Fenske
and
Lu
(33)
reported
that
the
recovery
of
chlorpyrifos
from
hand
rinses
was,
at
the
most,
54%
after
a
known
amount
of
the
pesticide
was
transferred
to
the
hand.
This
incomplete
removal
of
the
pesticide
from
hands
may
allow
pesticides
to
persist
for
days
after
exposure
and
to
increase
with
repeated
contact.
Wester
and
Maibach
(32)
reported
that
malathion
exhibited
greater
percutaneous
absorption
with
increased
residence
time
on
the
skin
due
to
the
bind-
ing
of
the
pesticide
by
all
skin
layers.
Longer
durations
of
skin
contact
time
and
occlusion,
e.g.,
clothing,
enhanced
the
potential
for
increased
pesticide
absorption.
With
the
presence
of
each
of
these
possible
ways
to
increase
exposure
for
a
child,
the
range
of
our
dose
estimates
is
reasonable,
if
not
conservative.
The
results
of
the
current
study
also
indi-
cate
that
the
reentry
times
listed
on
pesticide
packaging should
not
be
based
on
air
levels
alone.
Because
the
highest
dose
is
obtained
through
dermal
and
nondietary
oral
path-
ways,
the
current
suggested
reentry
times
(1-3
hr
following
application)
will
fail
to
adequately
protect
children
from
nondietary
ingestion
and
dermal
exposure
because
of
the
two-phase
process
of
distribution
and
depo-
sition
of
particles
and
vapors.
Currie
et
al.
(16)
reported
that
building
occupants
could
return
to
their
offices
1
day
after
treatment
with
chlorpyrifos.
The
concentration
of
chlorpyrifos
was
roughly
one-eighth
the
threshold
limit
value
(TLV;
200
pg/m3)
4
hr
after
treatment,
and
it
fell
to
one-tenth
the
TLV
by
24
hr
after
treatment.
The
offices
were
unventilated,
and
reentry
into
the
rooms
was
suggested
as
being
safe
based
on
air
levels
measured
over
a
10-day
period.
The
exposure
analyses
for
the
present
study
sug-
gests
that
accumulation
of
chlorpyrifos
in
children's
toys
and
other
plush
objects
is
of
concern
for
public
health
and
that
these
objects
must
not
be
stored
in
an
open
room
for
at
least
a
week
after
a
single
application.
Further
research
is
necessary,
however,
to
obtain
a
distribution
of
exposure
and
pat-
terns
of
contact
in
order
to
evaluate
new
pro-
cedures
for
application
and
establish
appro-
priate
times
for
reentry
of
individuals
and
their
possessions.
For
example,
the
pesticide
product
labels
direct
the
consumer
to
avoid
reentry
until
sprays
have
dried;
however,
these
generic
instructions
fail
to
safeguard
against
chronic
exposure
to
pesticides.
On
examination
of
a
consumer
product
contain-
ing
chlorpyrifos
(Raid,
S.C.
Johnson
&
Son,
Inc.,
Racine,
WI),
it
was
noted
that
the
label
cautioned
children
and
pets
from
contacting
treated
areas
that
appeared
wet.
As
shown
in
our
study,
areas
and
surfaces
not
directly
treated
with
a
pesticide
are
equally
prone
to
pesticide
contamination
and
accumulation.
Wallace
et
al.
(34)
reported
measurable
air
levels
of
chlorinated
pesticides
such
as
aldrin
and
dieldrin
in
a
residence
7
years
following
initial
measurement.
Other
stud-
ies
have
noted
the
persistence
of
pesticides
in
carpets
(35-37).
In
a
study
by
Richter
et
al.
(38),
diazinon,
an
organophosphate
sim-
ilar
in
characteristics
to
chlorpyrifos,
was
found
on
the
walls
of
a
residence
at
12.6-105
ng/cm2.
The
inhabitants
experi-
enced
symptoms
such
as
fatigue,
nausea,
dizziness,
headaches,
and
heaviness
in
the
chest.
The
maximum
cholinesterase
depres-
sion
measured
was
21.6%
below
baseline
Volume
106,
Number
1,
January
1998
*
Environmental
Health
Perspectives
14
Articles
*
Accumulation
of
chlorpyrifos
in
childrens'
toys
levels
of
cholinesterase,
which
was
measured
15
months
after
the
initial
measurement.
In
our
study,
the
surface
loading
of
chlorpyri-
fos
ranged
from
3.6
to
54
ng/cm2
on
the
dresser
top
and
from
1,950
to
7,075
ng/cm2
on
plastic
toys,
indicating
that
the
potential
exposure
of
children
can
be
sub-
stantial
in
recently
or
repeatedly
treated
homes.
Thus,
a
long-term
consequence
of
leaving
toys
out
in
rooms
routinely
treated
with
pesticides,
such
as
those
used
in
our
study,
could
be
an
accumulation
of
high
levels
of
pesticides
in
toys
and
other
plush
objects
made
with
polyurethane
foam.
Pesticide
exposure
to
young
children
will
be
underestimated
if
chronic
exposures
from
dermal
and
nondietary
ingestion
from
con-
tact
with
pesticides
in
toys
and
other
furni-
ture
are
not
considered.
The
reported
exper-
iments
did
not
include
the
contribution
of
dietary
exposure
to
pesticides.
Previous
stud-
ies
have
suggested
that
many
of
the
pesti-
cides
applied
to
food
crops
in
this
country
are
present
in
food
in
trace
amounts
(4,7,39).
Thus,
families
that
routinely
use
pesticides
can
obtain
cumulative
chronic
dietary
and
nondietary
exposures
which
will
increase
the
body
burden
of
pesticides
in
children
to
values
above
current
reference
dose
(RfD)
of
3
glkg/day
[based
upon
a
no
observable
effect
level
(NOEL)
of
30
pg/kg/day],
the
dose
of
a
chemical
at
which
there
were
no
statistically
or
biologically
sig-
nificant
increases
in
frequency
or
severity
of
adverse
effects
seen
within
an
exposed
popu-
lation
and
its
appropriate
control
(40,41).
The
estimated
dose
is
also
above
the
allow-
able
daily
intake
(ADI)
for
residential
expo-
sures,
10
pg/kg/day,
which
is
based
upon
a
NOEL
for
plasma
cholinesterase
depression
of
100
pg/kg/day
(42).
When
the
1%
der-
mal
absorption
and
30%
oral
absorption
estimates
were
used,
the
total
nondietary
dose
of
64
pg/kg/day
still
exceeded
the
cur-
rent
ADI
by
a
factor
of
6
and
the
Rf)
by
a
factor
of
21.
The
health
effects
that
may
result
from
the
range
of
doses
described
above
are
unknown.
Thus,
issues
surround-
ing
the
risk-benefit
analysis
of
indoor
pesti-
cide
applications
must
be
evaluated
to
deter-
mine
the
need
for
sequestering
toys
before,
during,
and
after
an
application.
The
high
exposure
estimate
also
suggests
that,
in
some
cases,
acute
residential
exposures
may
be
substantial
and,
at
a
minimum,
warrant
fur-
ther
research
and
a
thorough
evaluation
of
household
exposure/biologically
effective
dose
for
the
above
pathway.
Conclusions
Surfaces
inside
residences,
such
as
furniture
and
toys,
can
serve
as
reservoirs
for
pesti-
cides.
The
accumulation
of
semivolatile
pes-
ticides
in
such
objects
follows
a
two-stage
process
whereby
chlorpyrifos,
the
pesticide
examined
in
this
study,
is
initially
attached
to
a
particle
released
during
application
and
deposited
on
a
surface.
Subsequently,
it
is
released
from
the
surface
as
a
vapor
and
is
eventually
sorbed
by
furniture
and
toys.
Current
suggested
reentry
times
fail
to
ade-
quately
safeguard
young
children
from
expo-
sure
due
to
their
play
time
with
toys,
contact
with
other
plush
objects,
and
frequency
of
mouthing
behavior.
The
study
implies
that
toys
should
be
stored
during
the
application
and
for
many
days
after
application
to
reduce
the
available
residue
on
toys
duringl
play
and
to
prevent
significant
exposures
to
pesticides
by
this
nondietary
pathway.
Research
in
sup-
port
of
a
thorough
risk-benefit
study
must
be
conducted
to
identify
the
need
for
recom-
mendations
that
can
limit
toy
contact
with
pesticides
and
reduce
the
potential
for
chron-
ic
doses
above
an
RfD
or
an
ADI.
This
is
essential
to
ensure
that
children
continue
to
be
protected
from
consequences
of
insect
infestations,
but
at
the
same
time
minimize
long-term
exposures
and
potential
risks
from
pesticide
accumulation
in
their
toys
and
play
environments.
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cho
lof'
he
NV
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Mo
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>.~~~~~~~~~~~~~~~~~u,
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74
75
76
W
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Os
Center
I
Env~~~~~~~~~~~~~~~~~_SIironmnta
Contact
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1997-98
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