Journal of Exposure Science and Environmental Epidemiology (2007) 17, 331–349
r 2007 Nature Publishing Group All rights reserved 1559-0631/07/$30.00
www.nature.com/jes
Pesticides and their Metabolites in the Homes and Urine of Farmworker
Children Living in the Salinas Valley, CA
ASA BRADMANa, DONALD WHITAKERb, LESLIAM QUIRÓSa, ROSEMARY CASTORINAa, BIRGIT CLAUS
HENNc, MARCIA NISHIOKAd, JEFFREY MORGANe, DANA B. BARRf, MARTHA HARNLYg,
JUDITH A. BRISBINh, LINDA S. SHELDONb, THOMAS E. MCKONEa,i AND BRENDA ESKENAZIa
a
Center for Children’s Environmental Health Research, School of Public Health, University of California, Berkeley, CA, USA
US Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development, Research Triangle Park, NC, USA
c
ASPH Environmental Health Fellow, US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Office of
Research and Development, Research Triangle Park, NC, USA
d
Battelle Memorial Institute, Columbus, OH, USA
e
US Environmental Protection Agency, National Exposure Research Laboratory, Office of Research and Development, Cincinnati, OH, USA
f
National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
g
Environmental Health Investigations Branch, California Department of Health Services, Richmond, CA, USA
h
Oak Ridge Institute for Science and Technology, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Cincinnati, OH, USA
i
Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, USA
b
In support of planning efforts for the National Children’s Study, we conducted a study to test field methods for characterizing pesticide exposures to 20
farmworker children aged 5–27 months old living in the Salinas Valley of Monterey County, California. We tested methods for collecting house dust,
indoor and outdoor air, dislodgeable residues from surfaces and toys, residues on clothing (sock and union suits), food, as well as spot and overnight
diaper urine samples. We measured 29 common agricultural and home use pesticides in multiple exposure media samples. A subset of organophosphorus
(OP), organochlorine (OC) and pyrethroid pesticides were measured in food. We also analyzed urine samples for OP pesticide metabolites. Finally, we
administered four field-based exposure assessment instruments: a questionnaire; food diary; home inspection; and a self-administered child activity
timeline. Pesticides were detected more frequently in house dust, surface wipes, and clothing than other media, with chlorpyrifos, diazinon, chlorthaldimethyl, and cis- and trans-permethrin detected in 90% to 100% of samples. Levels of four of these five pesticides were positively correlated among the
house dust, sock, and union suit samples (Spearman’s r ¼ 0.18–0.76). Pesticide loading on socks and union suits was higher for the group of 10 toddlers
compared to the 10 younger crawling children. Several OP pesticides, as well as 4,40 -DDE, atrazine, and dieldrin were detected in the food samples. The
child activity timeline, a novel, low-literacy instrument based on pictures, was successfully used by our participants. Future uses of these data include the
development of pesticide exposure models and risk assessment.
Journal of Exposure Science and Environmental Epidemiology (2007) 17, 331–349; doi:10.1038/sj.jes.7500507; published online 31 May 2006
Keywords: pesticides, children, exposure, agriculture, union suits.
Introduction
Since the publication of ‘Pesticides in the diets of infants and
children’ in 1993 (NRC, 1993) and the passage of the Food
Quality Protection Act (FQPA) in 1996, public health
concerns about pesticide exposures to young children have
received increased attention. Recent studies have confirmed
1. Address all correspondence to: Dr. Asa Bradman, Center for Children’s
Environmental Health Research, School of Public Health, University of
California, Berkeley, 2150 Shattuck Avenue, Suite 600, Berkeley, CA
94720-7380, USA.
Tel.: þ 1 510 643 3023. Fax: þ 1 510 642 9083.
E-mail: abradman@socrates.berkeley.edu
Received 19 October 2005; accepted 4 May 2006; published online 31 May
2006
pesticide contamination in home and day care environments
where children spend most of their time (Adgate et al., 2001;
Karmaus et al., 2001; Fenske et al., 2002a; Curl et al., 2003;
Wilson et al., 2004). Biomonitoring studies have demonstrated that children are widely exposed to a number of
pesticides, including organophosphorus (OPs), pyrethroid,
fungicide, and organochlorine (OC) pesticides (Bradman
et al., 1997, 2003; Aprea et al., 2000; Fenske et al., 2000a;
Adgate et al., 2001; Lu et al., 2001; Wilson et al., 2003; Barr
et al., 2005). The effects of these exposures on children’s
health are largely unknown. However, epidemiologic studies
are currently investigating whether pre- and/or postnatal
exposure to pesticides is associated with adverse health
outcomes such as poorer growth and neurodevelopment in
children (Berkowitz et al., 2004; Eskenazi et al., 2004,
Whyatt et al., 2004; Young et al., 2005). Additionally, key
A Bradman et al
hypotheses of the National Children’s Study, a multiagency
longitudinal cohort study of 100,000 children to be followed
from conception until young adulthood, focus on the
association of pesticide exposure with adverse health effects
in children (Branum et al., 2003).
In contrast to risk assessment studies that attempt to
classify the range of exposures in a population, epidemiological studies require accurate classification of individual-level
exposures. However, accurately characterizing children’s
exposures to current-use pesticides is challenging because of
the nonpersistent nature of these chemicals and the variability
in how they are metabolized (Cohen Hubal et al., 2000a, b;
Fenske et al., 2002a, b; Branum et al., 2003; Clayton et al.,
2003; Bradman and Whyatt, 2005).
Several studies suggest that children living in agricultural
areas or with farmworker families are exposed to OP pesticides
(Simcox et al., 1995; Loewenherz et al., 1997; Lu et al., 2000;
O’Rourke et al., 2000; McCauley et al., 2001; Koch et al.,
2002; Quandt et al., 2004). Farmworker children may be
particularly vulnerable to pesticide exposure because they can
experience exposures via multiple pathways such as pesticide
drift from nearby fields, parental take-home exposure, and
breast milk from the farmworker mother (Camann et al.,
1995; Simcox et al., 1995; Fenske, 1997; Eskenazi et al., 1999;
Fenske et al., 2000b, 2002b; Lu et al., 2000; McCauley et al.,
2001; Curl et al., 2002; Thompson et al., 2003; Quandt et al.,
2004; Lambert et al., 2005). In support of the National
Children’s Study and our own exposure modeling efforts, we
conducted a study to test multimedia sampling methods to
assess pesticide exposure to farmworker children living in the
agricultural area of the Salinas Valley, CA.
Methods
Study Population
We enrolled a convenience sample of 20 children residing in
the Salinas Valley, Monterey County, California. Families
were recruited through local community clinics, social service
organizations, and word-of-mouth. Eligible participants were
either 6–12 months old and not able to walk (crawling) or
approximately 24 months old and able to walk (toddler), and
had at least one farmworker parent 18 years or older living in
the same household. A total of 10 boys and 10 girls were
recruited, with equal gender distribution in each age group.
All sampling occurred between June and September, 2002.
All procedures were reviewed and approved by the
University of California, Berkeley Institutional Review
Board (IRB).
Data Collection/Field Instruments
For each family participating in the study, we performed a
total of three visits over 3 days. During the first study visit,
we obtained signed informed written consents from partici332
Pesticides in Children’s Homes and Urine
pants. In addition, we provided an overview of the urine and
environmental sampling procedures, provided supplies for
overnight urine sample collection, and distributed the toys
and teething rings. During the second study visit, we
administered questionnaires, collected spot urine samples,
retrieved overnight urine samples, provided an overview and
demonstration of the CAT and recall log, distributed union
suits and socks, performed home inspections, collected
surface wipe and press samples, set up indoor and outdoor
air samplers, and collected house dust and food samples.
During the third study visit, we retrieved indoor and outdoor
air samplers, food 2005, union suit, and sock samples. In
addition, we collected toy and teething ring wipe samples,
and administered the child activity recall logs and 24-h food
diaries. The field instruments and sample collection methods
are summarized in Table 1 and described below.
Questionnaire Bilingual/bicultural study staff administered
questionnaires in either English or Spanish to the child’s
parents. Information obtained included a household
enumeration, the parents’ and other household members’
occupations, behaviors potentially related to take-home
exposures, home pesticide use, pets in the home, the child’s
activities, and exposure-related behaviors.
Home Inspection At the home inspection, staff recorded
the types of floor surfaces (wood, linoleum, carpet, etc.) in
each room, distance of the home to the closest agricultural
field or orchard, overall quality of the housekeeping, and an
inventory of all home pesticides and active ingredients.
Child Activity Timeline and Recall Log A time-activity
diary was created for the mother or adult relative to record
the child’s location and activity during the 24-h period
coincident with collection of the personal and air samples (see
below). Each page of the form covered a 12 h period. Parents
were asked to record the dominant activity and room the
child was in for 30 min increments. Six activity levels were
defined: sleeping, eating, quiet play (e.g., drawing), active
play (running or jumping), watching television, and sitting in
a stroller, carriage or car seat. Macro-location (i.e., inside or
outside home) and microlocation (i.e., room in the house)
categories were specifically defined and made visually distinct.
Pictures were used to represent locations and activities to
facilitate use by low-literacy respondents. Extensive training
on how to complete the CAT was provided by study staff to
ensure accurate completion. At the end of the 24-h sampling
period, study staff verified responses with participants while
transferring information from the child activity timeline
(CAT) into a computer-codeable form for data entry (Recall
Log). While completing the Recall Log, additional
information was also obtained on the amount of time
children spent on specific surfaces (e.g., wood floor, carpet,
grass) and garments worn by the children during the
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
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A Bradman et al
Table 1. Collection methods and field instruments for pesticide samples.
Matrix
Collection method/exposure information attained
House dust
HVS3 vacuum cleaner and HVS3 attachment
Air (indoor, outdoor)
24-h integrated sample (target flow rate 2.5 l/min)
Surface press (floor)
5-min sample (total contact area of 114 cm2 and a contact pressure of 11.8 g/cm2)/Two C18 90 mm extraction
disks (3M EmporeTM)
Surface and toy wipe
Soft-wick sponges (2 400 400 6-ply sponges with 10 ml isopropanol)
Duplicate food (solid)
Plastic zip closure bags in two sizes (quart and gallon size)
Duplicate food (liquid)
Nalgene bottle (quart size)
Leftover handled food (solid, liquid)
Plastic zip closure bags in two sizes (quart and gallon size) and Nalgene bottle (quart size)
Clothing
Cotton union suits and cotton socks (sampling time: 3–4 h)
Urine
Sterile U-bag/Specipan or urine collection cup 10–25 ml aliquots and diaper. One spot sample and one overnight
diaper sample were collected
Study instruments
Questionnaires
Occupational pesticide contact, proximity to fields, use and storage of home pesticides, and child’s activities and
diet
Home inspections
Home inspection to record details of home and
surroundings (i.e., proximity to agricultural fields), room-by-room assessment, overall conditions of the home,
and home pesticide use and active ingredient(s)
Child activity timelines (CAT)
Self-administered visual diary for participant’s parents to record child’s activities and location during the 24-h
monitoring period
Recall log
Numerically coded log to improve reliability and accuracy of child activity timeline (CAT)
Food diaries
Self-administered diary for participants’ parent(s) to record child’s daily food intake.
sampling period (long versus short pants, long versus short
sleeve shirts, etc).
Food Diary Parents were asked to record all food items
consumed by the child during the 24-h period after consent
was obtained. Information recorded included type of food,
portion size, and time of consumption. Study staff reviewed
the food diary with the parent(s) to determine how
representative this sample was of the child’s typical diet.
Environmental, Personal, and Biological Sample Collection
Over 3 days of sampling, we collected house dust, surface
press, surface and toy wipe and 24-h indoor and outdoor air
samples from 20 farmworker homes. We also collected
children’s clothing samples, 24-h duplicate diet and leftover
handled food samples, as well as one spot urine and one
overnight diaper urine sample (Table 1).
House Dust We used the High Volume Surface Sampler
(HVS3) (Roberts et al., 1991) to collect carpet dust samples
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
from mostly carpeted living area floors and, in one case, a
carpeted dining room, where children spent time playing.
One sample was collected from a bare wood floor. Samples
were collected from one square meter areas according to
procedures defined in the American Society for Testing
Materials (ASTM) Standard Practice D 5483–94 (ASTM,
1997).
Surface Wipes (Floors and Toys/Pacifiers) Approximately 1.5 days (range: 1–6 days) before sampling, study
staff provided a teething ring (area ¼ 99.2 cm2) and a small
ball (area ¼ 283.5 cm2) to the crawling children and toddlers,
respectively. We collected surface wipes from the floors and
age-appropriate toys. Floor wipes were obtained from a
central location, usually the kitchen or dining area, near the
boundary with carpeted floors. A defined surface area on the
floor or indoor play area of 30 30 cm and the entire surface
of the toys were thoroughly wiped using 10 10 cm Johnson
and Johnson SOF-WICK rayon dressing sponges dampened
with reagent-grade isopropanol alcohol (Geno et al., 1996).
333
Pesticides in Children’s Homes and Urine
A Bradman et al
Surface Presses We used a surface press to estimate
transferable residues from floors to skin. The press
consisted of a custom built sampling device based on the
EL press sampler (Edwards and Lioy, 1999). C18
impregnated Teflon extraction disks (3M Empore disks)
were mounted on the press, which was then placed on hard
floor surfaces (linoleum or wood), with the exception of one
sample that was collected from a carpeted surface.
Indoor/Outdoor Air Indoor monitors were placed in the
main living area approximately 0.5–1.5 m above the floor.
Outdoor monitors were placed in a central area in the yard
and, when possible, at least 6 m away from driveways and
roadways. Indoor and outdoor air samples were collected
over a 24-h period using polyurethane foam (PUF)
cartridges, resulting in a nominal sampled air volume of
3,600 l. The target flow rate for the cartridges was 2.5 l/min.
Pumps were secured in a tamper resistant box for indoor
monitoring and a tamper- and weather-resistant box for
outdoor monitoring. At the end of the monitoring period, the
PUF cartridge was placed in a glass jar, capped, and stored
until shipped for laboratory extraction and analysis.
Duplicate Diet and Leftover Handled Food To estimate
pesticide levels in ingested food, 24-h duplicate diet samples
were collected from each child’s family. Parents were asked to
prepare twice the amount of food normally prepared for the
child and to collect the same amount of food the child
ingested throughout the day. Liquid diet (including formula)
or duplicate beverage samples and solid foods were collected
for the crawling children and placed in a container provided
by the study staff. For the toddlers, liquid and solid foods
were collected in separate containers that were provided to
participants. To estimate residues transferred to foods from
the children’s hands or from contaminated dusts in the home,
leftover handled solid foods, when available, were also
collected for this age group.
Union Suits and Socks In order to assess potential dermal
loading, participants were provided cotton one-piece
playsuits (union suits) and socks. Participants wore the
garments while at home for an average duration of 4.0 h.
(SD ¼ 2.3). At the end of the activity period, garments were
removed, cut into segments, and stored in plastic zip closure
bags prior to shipping to the laboratory for pesticide analysis.
Child Urine Two urine samples were collected from each
child during the 24-h sampling period: one spot sample and
one overnight diaper sample. Procedures used were those
outlined by the Centers for Disease Control and Prevention
(CDC) for use in the National Health and Nutrition
Examination Survey 1999–2000 (NHANES) (CDC, 2003).
For the spot urine samples, toilet-trained children were asked
to void in a cleaned specimen container (Specipan; Baxter
334
Scientific, McGaw Park, IL). For children who were not
toilet-trained, a standard infant urine collection bag
(Hollister) was affixed by its adhesive surface to the pubic
area and held in place with the diaper. The bag was removed
at the end of the visit. If, for any reason, the child could not
provide any of the samples during the visit, a spot sample was
collected on the day after the overnight diaper was collected
(see below). For the overnight diaper sample, we provided
the adult respondent with a disposable diaper containing a
sewn-in Johnson and Johnson SURGIPAD combine
dressing (Hu et al., 2000). The next morning, study staff
collected this diaper when the air and food samples were
collected. The total weight of the diaper was recorded, and
then the insert was expressed and the volume recorded. For
quality control purposes, frozen field blanks and spikes,
prepared earlier by CDC, were defrosted, re-packaged in the
field according to collection procedures for actual samples,
and then shipped blind with the unknown samples to CDC.
Laboratory Analysis
Environmental and Clothing Samples All environmental
and clothing samples were stored on ice packs in the field and
during transport to the field laboratory, where they were
stored at 801C until shipment to the analytical laboratory
(Battelle Memorial Institute, Columbus, Ohio). Samples
were stored at the laboratory at 201C until extraction and
analysis.
Environmental (house dust, indoor/outdoor air, surface
wipes, and C18 surface press disks) and clothing samples
(union suits and socks) were analyzed for 12 OP pesticides,
13 pyrethroids, two fungicides, two OCs, and one herbicide
(Tables 2 and 3). Target analytes were chosen based on the
amount of local agricultural use, the likelihood of home
pesticide use, and laboratory feasibility. All sample types
were spiked with a mixture of surrogate recovery standards
(SRSs), cleaned with a solid phase extraction (SPE) method
(except for C18 press disk samples), and analyzed using gas
chromatography/mass spectrometry (GC/MS) in selected ion
monitoring (SIM) mode. Extract concentrations were
quantified based on a 7-point linear calibration curve. The
SRSs were chosen to reflect general compound classes and/or
polarity ranges of the analytes; they were spiked at 100 ng for
air and C18 press disks and 250 ng for other matrices. The
SRSs included 13C12-p, p0 -DDE, 13C12- p,p0 -DDT, 1:1 mix
of 13C6-cis-permethrin and 13C6-trans-permethrin, fenchlorphos, d10diazionon, and 13C1-diethyl acetamidomalonate
(13C1-DEAA).
Dust samples were sieved to obtain the dust fraction
o150 mm for analysis. A 0.5 g aliquot was spiked with the
SRSs, and extracted by sonication with 12 ml of 1:1
hexane:acetone. The SPE cleanup step on silica (1 g,
BakerBond) included sequential elution with hexane, 15%
diethyl ether in hexane, dichloromethane (DCM) and 20%
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 2. Limits of detection and detection frequencies for the target analytes in multimedia samples.
House dust
(ng/g)
Analyte
Organophosphorous pesticides
Acephate
Chlorpyrifos
Diazinon
Dichlorvos
Dimethoate
Fonofos
Malathion
Phosmet
Azinphos-Methylb
Chlorpyrifos Oxonb
Methidathionb
Pyrethroids
cis-Allethrin
trans-Allethrin
Bifenthrin
Cyfluthrind
l-Cyhalothrin
Cypermethrind
Deltamethrin
Esfenvalerate
cis-Permethrin
trans-Permethrin
Resmethrin
Sumithrin
Tetramethrin
Other
Chlorthal-dimethyl (herbicide)
p,p0 -DDE (OC)
p,p0 -DDT (OC)
Iprodione (fungicide)
Vinclozolin (fungicide)
Indoor air
(ng total)
Outdoor air
(ng total)
Surface wipe
(ng total)
Toy wipe
(ng total)
LOD
DF
(%)
LOD
DF
(%)
LOD
DF
(%)
LOD
DF
(%)
LOD
DF
(%)
10
2
2
10
10
2
2
2
0
95
100
0
0
0
20
0
10
1
1
2
10
1
2
2
0
100
100
5
0
0
15
0
10
1
1
2
10
1
2
2
0
85
100
10
0
0
40
0
50
5
2
10
25
2
10
2
0
95
95
5
0
0
20
0
50
5
2
10
25
2
10
2
25
10
10
0
0
0
50
2
2
0
0
0
50
2
2
0
0
0
25
10
5
0
0
0
5
5
1
200
10
200
200
10
2
2
5
2
4
25
25
5
10
20
40
5
5
100
100
0
20
0
2
2
1
100
10
100
50
25
2
2
2
2
4
15
15
5
0
0
5
0
0
40
16e
0
10
0
2
2
1
100
10
100
50
25
2
2
2
2
4
0
0
5
0
0
0
0
0
30
0e
0
0
0
5
5
1
200
10
200
250
10
2
2
10
2
4
2
2
10
10
10
100
60
10
35
0
100
40
0
0
0
1
1
10
10
10
0.5
1
5
25
2
100
30
5
0
0
0.5
1
5
25
2
Cotton socks
(ng total)
Union suits
(ng total)a
LOD
DF
(%)
LOD
DF
(%)
5
30
60
0
0
5
5
0
50
5
2
2
50
2
25
25
0
89
95
0
5
0
16
0
100
4
2
4
200
4
20
25
0
100
100
0
0
0
25
5
25
10
5
0
0
0
25
50
25
0
0
0
Fc
50
4
Fc
0
0
20
20
5
5
5
40
0
0
85
95
0
15
0
5
5
1
200
10
200
250
10
2
2
10
2
4
0
0
5
0
0
0
0
0
15
15
0
0
0
5
5
2
1000
25
1000
500
25
2
2
10
10
20
10
10
32
5
0
5
0
10
100
100
10
10
0
10
10
4
800
100
800
200
50
4
4
100
50
8
20
20
30
5
5
0
0
0
100
100
0
5
10
100
15
0
20
0
1
1
10
10
10
55
0
0
0
0
2
2
10
250
10
95
74
5
10
0
2
4
50
200
20
100
55
10
10
0
a
Union suit sample is a composite of four sections: leg, arm, upper and lower torso.
Analytes not detected in any of these seven matrices.
No calibration curve obtained, due to injector fouling.
d
Detection limit when all four chromatographically resolved isomers are detected.
e
One sample missing.
Abbreviations: DF ¼ Detection frequency; LOD ¼ Limit of detection; OC ¼ Organochlorine.
b
c
acetone in ethyl acetate. The hexane fraction was discarded.
Since p,p0 -DDE eluted partially in the discarded hexane
fraction, the recovery of SRS 13C12-p,p0 -DDE was used to
correct for this planned loss of p,p0 -DDE. The internal
standard (IS) dibromobiphenyl (100 ng) was added to the
final 1 ml extract.
Air (indoor and outdoor) and surface wipe samples were
extracted using accelerated solvent extraction (ASE) at
2000 psi and 1001C. Samples were extracted in sequence with
9:1 and 1:1 hexane:acetone. Extracts were combined, cleaned
up as described above, and analyzed using GC/MS/SIM.
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
The C18 surface press disks were extracted on a shaker
table for 30 min in 1:1 DCM:ethyl acetate, and concentrated
to 1 ml for analysis.
Before sampling, union suits were washed multiple times in
hot water and mild detergent. After sampling, they were cut
into four segments (upper torso, arms, bottom torso, and
legs), and each segment was extracted separately in a Soxhlet
extractor with 250 ml of DCM for 14–16 h. Similar
extraction methods were used for socks. A gelatinous
flocculate formed during the concentration step and became
more pronounced with the solvent exchange of the extracts
335
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 3. Pesticide concentrations in multimedia samples (n ¼ 20 children)a.
House dustb (ng/g)
Indoor air (ng/m3)
Outdoor air (ng/m3)
Analyte
p25
p50
p75
Range
p25
p50
p75
Range
p25
p50
p75
Range
Organophosphorous pesticides
Acephate
Chlorpyrifos
Diazinon
Dichlorvos
Dimethoate
Fonofos
Malathion
F
40
10
F
F
F
F
F
49
21
F
F
F
F
F
76
32
F
F
F
F
F
ND-1,200
4.0–810
F
F
F
ND-480
F
9.4
9.4
F
F
F
F
F
11
12
F
F
F
F
F
15
21
F
F
F
F
F
4.0–36
5.9–260
ND-150
F
F
ND-50
F
4.0
11
F
F
F
F
F
6.0
17
F
F
F
F
F
9.0
35
F
F
F
18
F
ND-36
6.2–140
ND-200
F
F
ND-90
Pyrethroids
cis-Allethrin
trans-Allethrin
Bifenthrin
l-Cyhalothrin
Cyfluthrin
Cypermethrin
Deltamethrin
Esfenvalerate
cis-Permethrin
trans-Permethrinc
Resmethrin
Sumithrin
F
F
F
F
F
F
F
F
57
140
F
F
F
F
F
F
F
100
F
F
150
230
F
F
70
60
F
F
F
420
F
F
210
570
F
F
ND-2,500
ND-2,800
ND-30
ND-140
ND-300
ND-1,500
ND-560
ND-50
13–2,900
22–5,800
F
ND-5,500
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
5.4
F
F
F
ND-63
ND-61
ND-3.1
F
F
ND-380
F
F
ND-8.2
ND-11
F
ND-96
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
7.1
F
F
F
F
F
ND-2.8
F
F
F
F
F
ND-8.0
F
F
F
19
F
FF
F
31
17
F
F
61
20
F
20
6.5–110
ND-860
ND-140
ND-1,400
7.5
F
F
F
12
F
F
F
19
2.0
F
F
1.8–43
ND-28
ND-31
F
11
F
F
F
25
F
F
F
46
4.6
F
F
5.0.-83
ND-10
F
F
Other
Chlorthal-dimethyl (herbicide)
p,p0 -DDE (OC)
p,p0 -DDT (OC)
Iprodione (fungicide)
Surface(floor) wipe(ng/cm2)
Analyte
Toy wipe (ng/cm2)
Cotton socksd (ng/sample)
p25
p50
p75
Range
p25
p50
p75
Range
p25
p50
p75
Range
Organophosphorous pesticides
Acephate
Chlorpyrifos
Diazinon
Dichlorvos
Dimethoate
Fonofos
Malathion
F
0.017
0.011
F
F
F
F
F
0.046
0.038
F
F
F
F
F
0.079
0.066
F
F
F
F
F
ND-0.20
ND-0.096
ND-0.083
F
F
ND-0.69
F
F
F
F
F
F
F
F
F
0.014
F
F
F
F
F
0.052
0.034
F
F
F
F
ND-0.20
ND-0.15
ND-0.27
F
F
ND-0.084
ND-0.21
F
14
5.7
F
F
F
F
F
24
11
F
F
F
F
F
37
20
F
F
F
F
F
ND-66
ND-590
F
ND-54
F
ND-300
Pyrethroids
cis-Allethrin
trans-Allethrin
Bifenthrin
l-Cyhalothrin
Cyfluthrin
Cypermethrin
Deltamethrin
Esfenvalerate
cis-Permethrin
trans-Permethrin
Resmethrin
Sumithrin
F
F
F
F
F
F
F
F
0.053
0.14
F
F
F
F
F
F
F
F
F
F
0.10
0.23
F
F
F
F
F
F
F
0.34
F
F
0.21
0.39
F
F
ND-2.0
ND-2.2
ND-0.035
ND-0.026
ND-0.40
ND-2.8
F
F
ND-1.7
ND-3.6
F
ND-3.5
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
ND-0.14
F
F
F
F
F
ND-0.053
ND-0.072
F
F
F
F
F
F
F
F
F
F
50
140
F
F
F
F
F
F
F
F
F
F
120
220
F
F
F
F
19
F
F
F
F
F
380
490
F
F
ND-1,600
ND-1,500
ND-92
F
ND-1,400
ND-2,400
F
ND-230
17–5,600
10–9,200
ND-130
ND-2,100
336
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 3. Continued.
Surface(floor) wipe(ng/cm2)
Analyte
Other
Chlorthal-dimethyl (herbicide)
p, p0 -DDE (OC)
p, p0 -DDT (OC)
Iprodione (fungicide)
Toy wipe (ng/cm2)
Cotton socksd (ng/sample)
p25
p50
p75
Range
p25
p50
p75
Range
p25
p50
p75
Range
0.022
F
F
F
0.044
F
F
F
0.079
F
F
F
0.0018–0.28
ND-0.15
F
ND-0.53
F
F
F
F
0.0059
F
F
F
0.012
F
F
F
ND-0.035
F
F
F
9.8
F
F
F
16
28
F
F
31
52
F
F
ND-200
ND-86
ND-13,000
ND-11,000
a
Analyte concentrations presented only when detectable levels were measured in 1 or more matrices.
House dust samples are collected from 1 square meter surface.
c
One missing trans-permethrin house dust sample measurement.
d
One participant’s sock sample was missing.
Abbreviations: ‘F’ and ND ¼ Nondetectable; OC ¼ Organochlorine.
b
into hexane prior to SPE cleanup. The extract was
centrifuged at 3000 r.p.m., and the supernatant was removed
for SPE cleanup. When flocculate again formed after SPE
cleanup, ethyl acetate was added and a small portion of this
extract was then filtered into the GC vial. Although
analytical recoveries were acceptable (see below), performance of the GC/MS injection liner, column, and ion source
was compromised by the flocculate, and these parts had to be
cleaned or replaced frequently.
The extracts were analyzed using a Hewlett Packard (HP)
6890 GC interfaced to an HP 5973 MS. The gas
chromatography conditions included: a DB-1701 column
(30 m 0.25 mm id 0.15 mm film thickness); temperature
program of 701C for 2 min, then 70–1301C at 25 C/min,
130–2201C at 2 C/min, and 220–2801C at 10 C/min.
For each sample type, the analyses included multiple (2–5)
field matrix blanks and spikes, laboratory matrix blanks and
spikes, and duplicate analyses of house dust. Field matrix
spiked samples were fortified with all analytes, then handled,
transported, stored and analyzed as field samples. Laboratory matrix spiked samples were fortified just before
extraction with all analytes. Analyte spike levels were
250 ng of each analyte, with the exception of acephate,
naled, and the pyrethroids, which were spiked at 1000 ng.
Naled was detected as its degradation product dichlorvos.
There were no field matrix spikes for the dust or the union
suit matrices (although there were multiple laboratory spiked
samples of these matrices); the field spiked sock matrix was
used to represent the union suit matrix.
With the exception of cis- and trans-permethrin in the sock
and union suit matrices (215762 ng/sample and 5273 ng/
sample for cis- and trans-permethrin in socks; 31710 ng/
sample and 54755 ng/sample for cis- and trans-permethrin
in union suits), there were only rare instances when any
analyte was detected in a field or laboratory matrix blank.
Recoveries of the pyrethroids in all field spiked matrices
averaged 87% (90% for related SRSs); recoveries of the OPs
and other compounds (chlorthal-dimethyl, iprodione, vinJournal of Exposure Science and Environmental Epidemiology (2007) 17(4)
clozoline) in all field spiked matrices averaged 76% (99% for
related SRSs). Recoveries of the pyrethroids in all laboratory
spiked matrices averaged 87% (87% for related SRSs);
recoveries of the OPs and other compounds in all laboratory
spiked matrices averaged 78% (89% for related SRSs).
Duplicate analysis of one dust sample showed very good
agreement for the three analytes detected: 3.570.5 ng/g for
diazinon, 9.570.5 ng/g for chlorthal-dimethyl, and
1471 ng/g for cis-permethrin.
Food Samples Target analytes for the food analyses
included a range of OP, OC, and pyrethroid pesticides and
fungicides. Food samples were stored on ice packs in the field
and during transport to the field laboratory, where they were
stored at 801C, until shipment on dry ice to the analytical
laboratory (US EPA, National Exposure Research
Laboratory, Office of Research and Development,
Cincinnati, Ohio). Food samples were defrosted and
homogenized. For analysis of OP pesticides, solid food and
beverage samples were extracted using pressurized fluid
extraction with methylene chloride:acetone (1:1 v:v).
Extracts were cleaned up using a diatomaceous earth
chromatography column attached to the top of a C18
column. Organo-phosphorus pesticides were eluted with
acetonitrile saturated with hexane. Analysis was performed
using gas chromatography with pulsed flame photometric
detection (GC/PFPD). The initial analysis was performed on
an OP Pesticide column, 30 m 0.32 mm ID (Restek,
Bellefonte, PA, USA). Confirmation analysis was performed
on an OPPesticide2 column (Restek, Bellefonte, PA, USA).
For non-OP pesticides, homogenized solid food and
beverage samples were extracted using pressurized fluid
extraction with hexane:acetone (1:1, v:v). Extracts were
cleaned up using a diatomaceous earth chromatography
column eluted with acetonitrile saturated with hexane
followed by an alumina column eluted with methylene
chloride:hexane (70:30, v:v). Analysis was performed using
GC/MS in the SIM mode (Rosenblum et al., 2001). The
337
Pesticides in Children’s Homes and Urine
A Bradman et al
average recovery of non-OPs from composite solid foods was
79% and ranged from 60% to 108% for 22 of 23 analytes
tested. Recovery of one analyte, chlorothalonil, was below
60%. The average recovery of non-OPs from composite
beverages was 72% and ranged from 61% to 79% for 17 of
23 analytes tested. Recovery of aldrin, chlorthalonil,
heptachlor, hexachloro-benzene, simazine and trifluralin
was below 60%. The average recovery of OPs from
composite solid foods was 84% and ranged from 65% to
106%. The average recovery of OPs from composite
beverages was 76% and ranged from 60% to 94%.
Detection limits for all target analytes ranged from 0.5 to
6 ng/g (Table 7).
Urine Samples The urine samples were stored on ice packs
in the field and during transport to the field laboratory, where
they were stored at 801C until shipment to the laboratory
for analysis (CDC, National Center for Environmental
Health, Atlanta, Georgia). Six non-specific dialkyl phosphate (DAP) OP metabolites were measured F three
dimethyl phosphates: dimethylphosphate (DMP), dimethylthiophosphate (DMTP), and dimethyl-dithiophosphate
(DMDTP); and three diethyl phosphates: diethylphosphate
(DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP). These metabolites derive from
approximately 28 OP compounds registered in the US,
representing approximately 81% of OP pesticide use in the
Salinas Valley. Urine specimens were lyophilized to remove
water then the residue was redissolved in acetonitrile:diethyl
ether (1:1). The DAPs were derivatized to their chloropropyl
phosphate esters. The concentrated extracts were then
analyzed by isotope dilution gas chromatography-tandem
mass spectrometry (GC-MS/MS) (Bravo et al., 2004), which
is widely regarded as the definitive technique for trace
analysis for DAP metabolites with detection limits of 1 ppb
or less (Shealy et al., 1996; Barr et al., 1999). Creatinine
concentrations in urine were determined using a
commercially available diagnostic enzyme method (Vitros
CREA slides, Ortho Clinical Diagnostics, Raritan, NJ,
USA).
Laboratory quality control included repeat analysis of
three in-house urine pools enriched with known amounts of
pesticide residues whose target values and confidence limits
were previously determined. The validity of each analytical
run was determined using the Westgard rules for quality
control (Westgard, 2003). Limits of detection (LODs) ranged
from 0.08 mg/l for DMDTP to 0.4 mg/l for DMP. We
assigned an imputed value of the LOD/O2 to levels below the
detection limit (Hornung and Reed, 1990; Barr et al., 2004).
For one toddler, the level for one of the six metabolites
(DMTP) from the overnight diaper sample was not readable
due to analytic interference. As metabolites within the
dimethyl phosphate group were highly correlated, the missing
value was imputed using regression analysis to predict the
338
missing metabolite level based on the other metabolite levels
for that child and that sample type.
Field quality control samples included blank, spike, and
duplicate urine samples. No metababolites were measured in
blank samples indicating that no contamination occurred in
the field during processing or shipment to the laboratory. For
field spiked samples, laboratory methods yielded an average
percent recovery of 96% for total DAPs.
As many OP pesticides devolve to more than one
metabolite in their class (diethyl or dimethyl phosphates),
quantities were converted to molar concentrations (nmol/l)
and summed to obtain the total concentrations of the diethyl
and dimethyl phosphates (Barr et al., 2004). We performed
all statistical analyses using both the creatinine-adjusted and
non-adjusted urine data and there were no significant
differences in our results. We chose not to adjust the
metabolite levels for creatinine due to concerns regarding
the validity of such adjustments for children (Barr et al.,
2005).
Data Analysis
Summary statistics were computed for all media. Spearman
correlation coefficients were calculated for overnight and spot
urine samples as well as for environmental and clothing
samples. All data analysis was performed with Stata Version
8 (StataCorp LP, College Station, TX, USA).
Results
Population Characteristics
The mean age of the crawling children (n ¼ 10) was 8.3
months (range ¼ 5–11) and of the toddlers (n ¼ 10) was 23.5
months (range ¼ 21–27). Gender was evenly distributed in
both age groups. Study participants generally represent the
farmworker population in the Salinas Valley agricultural
area, which is primarily low income, Spanish-speaking, from
Mexico or of Mexican descent, and low-literacy. In all, 40%
of participants had household members besides the parent(s)
working in agriculture, 50% of participants used some type
of pesticide in or around their homes in the three months
prior to the study visit, and 35% of participants lived within
400 m of the nearest agricultural field or orchard. In all, 40%
of participants stored some type of pesticide in or around
their homes; active ingredients included piperonyl butoxide
and pyrethrin and pyrethroid compounds. Pesticides were
used to kill fleas, flies and fungus.
Environmental and Clothing Samples
Analytical LODs and detection frequencies for the seven
sampled exposure media are presented in Table 2. Three of
the eleven OP pesticides measured (azinphos-methyl, chlorpyrifos oxon and methidathion), plus the fungicide vinclozolin were not detected in any of these media (Table 2).
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Pesticides in Children’s Homes and Urine
Table 3 presents results for the pesticides detected in house
dust, indoor and outdoor air, surface (floor) wipes, toy
wipes, and socks. A higher number of pyrethroids was
detected (11 analytes) when compared to the number of OP
pesticides detected (eight analytes). Pyrethroids were the class
of pesticides detected at the highest concentrations in house
dust, indoor air, and surface wipes. Only two pyrethroids
were detected in outdoor air, whereas indoor air samples
contained seven pyrethroids. No analytes were detected in
surface press samples (data not shown), and fewer analytes
were detected in toy wipes than in floor wipes (Table 2). The
highest detection frequencies were found in house dust
samples, where concentrations ranged from o2.0 to
5,800 ng/g. Chlorpyrifos, diazinon, malathion, bifenthrin,
cis-permethrin, and chlorthal-dimethyl were found in all the
environmental media listed above (Table 3).
Data from sock samples are presented in Table 3. The
most frequently detected analytes (470%) in the cotton
socks were chlorpyrifos, diazinon, cis-permethrin, transpermethrin, chlorthal-dimethyl, and p,p0 -DDE (Table 2).
The highest concentration detected was 13,000 ng/sample for
p,p0 -DDT. Similar to union suit samples, more pyrethroids
were detected than OP pesticides (11/13 versus 4/11 analytes,
respectively), and concentrations of pyrethroids were generally higher than OP pesticides (ranges of o2.0–9,200 ng/
sample versus o2.0–590 ng/sample, respectively). Also,
among the most frequently detected analytes (X90%
detection frequency), higher concentrations were detected
for the older toddler children (Table 5). Other analytes
detected in socks include malathion, bifenthrin, cis-allethrin,
trans-allethrin, cyfluthrin, cypermethrin, esfenvalerate, resmethrin, sumithrin, and iprodione.
In the cotton union suit samples, the most frequently
detected (X90%) analytes were chlorpyrifos, diazinon, cispermethrin, trans-permethrin, and chlorthal-dimethyl (Tables
2 and 4). For most analytes, higher concentrations were
present in composite lower torso and leg sections than on top
torso and arm sections. More pyrethroids than OP pesticides
were detected (9 versus 3 analytes in composite union suits),
and pyrethroids were detected at higher concentrations than
OP pesticides (6.4–42,000 ng/sample for pyrethroids versus
2.0–2,100 ng/sample for OP pesticides). Ranges of total
detected union suit analyte concentrations for fungicides were
o200–19,000 ng/sample, o4.0–560 ng/sample for the OCs
and o2.0–350 ng/sample for the herbicide chlorthal-dimethyl (Table 4). Table 5 presents results for the composite
union suit and sock samples for the five most frequently
detected analytes. For four of the five analytes, median and
geometric mean levels were consistently higher for the older
children (toddlers) compared to the younger crawling
children. The ratio of geometric mean pesticide levels in the
toddler versus crawling children ranged from 1.1 to 2.6 ng/
sample in the union suits and from 1.5 to 3.0 ng/sample in
the socks. Table 6 presents the Spearman rank sum
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
A Bradman et al
correlation matrix for the five most frequently detected
analytes across the environmental and clothing sampling
media.
Food
Data from duplicate diet samples are presented in Table 7. In
all, 10 combined (liquid and solid) food samples from the
crawling children were analyzed, and 10 solid and 9 (one
missing) liquid food samples were analyzed from the
toddlers. In all, 15 leftover handled food samples (i.e.,
leftover liquid and/or solid food samples) were also collected
from the children and the majority of these samples were
from the toddlers (10/15). Out of 46 analytes, 13 were
detected in food samples. Detection frequencies were p30%
for these compounds. Solid and leftover handled food
samples had the highest number of detected analytes (6/46),
followed by combined food samples (5/46), and liquid food
samples (3/46). The highest analyte concentration detected
was in a solid food sample for a 22-month-old child (7.8 ng/g
of malathion). Analytes detected in the duplicate diet and
leftover handled food samples include: chlorpyrifos, diazinon, dieldrin, malathion, methamidophos, 4,40 -DDE, and
endosulfan. The dieldrin concentration in the leftover
handled food sample was slightly greater than that found in
the duplicate solid food sample (6.1 versus 4.8 ng/g) and the
malathion concentration in the leftover handled food sample
was lower than that in the duplicate solid food sample (1.8
versus 7.8 ng/g). Diazinon was only detected in the leftover
handled food. The only analyte detected in all food sample
types was methamidophos.
Urine
Results for spot and overnight diaper sample urinary
metabolite levels, unadjusted for creatinine, are presented in
Table 8. Median spot and overnight urine dimethyl
phosphate levels were higher than diethyl levels for both
age groups (Table 8). In all cases, diethyl phosphates were
lower in overnight diaper samples than in spot samples, while
for toddlers dimethyl phosphates were higher in overnight
diaper samples. Median overnight total DAP metabolite
concentrations were higher for the older versus the younger
children (180 versus 84 nmol/l, respectively), whereas the spot
total DAP levels were more similar (100 and 130 nmol/l).
Median total DAP concentrations for all children were
higher in the overnight samples compared to the spot samples
(140 versus 100 nmol/l), however, these differences were not
statistically significant (Wilcoxon signed-rank test).
Table 9 presents Spearman correlations calculated for spot
and overnight urine samples by age. The dimethyl phosphate
concentrations for the spot and overnight samples for all
children were significantly correlated (r ¼ 0.53; p ¼ 0.02).
The diethyl phosphate concentrations for the spot and
overnight diaper samples were also correlated (r ¼ 0.48;
p ¼ 0.03). Total DAP metabolites in spot and overnight
339
340
A Bradman et al
Table 4. Pesticide concentrations in cotton union suits (n ¼ 20 children).
Lower torso (ng/sample)
Analyte
Upper torso (ng/sample)
Arms (ng/sample)
Legsa (ng/sample)
Total burden (composite of all
4 sections) (ng/sample)b
p25 p50 p75
p75
Range
p25
p50
p75
Range
p25
p50
p75
Range
p25
p50
p75
Range
Organophosphorus pesticides
Chlorpyrifos
11 19
Diazinon
6.4 10
Malathion
F F
Phosmet
F F
28
22
35
F
6.7–93
3.4–490
ND-230
F
12
6.6
F
F
15
12
F
F
22
19
F
F
ND-53
2.4–1803
ND-410
F
6.9
4.6
F
F
11
6.9
F
F
20
12
F
F
ND-44
ND-210
ND-470
F
9.9
5.3
F
F
16
10
F
F
30
20
45
F
4.5–94
2.2–1,200
ND-190
ND-66
45
26
F
F
Pyrethroids
cis-Allethrin
trans-Allethrin
Bifenthrin
Cyfluthrin
l-Cyhalothrin
Cypermethrin
Esfenvalerate
cis-Permethrin
trans-Permethrin
Resmethrin
Sumithrin
Tetramethrin
F
F
12
F
F
F
F
330
100
F
F
F
ND-1,400
ND-1,600
ND-30
F
F
F
F
6.4–17,000
ND-11,000
F
ND-91
ND-290
F
F
F
F
F
F
F
110
40
F
F
F
F
F
F
F
F
F
F
150
64
F
F
F
F
F
4.1
F
F
F
F
260
200
F
F
F
ND-1,700
ND-1,600
ND-32
F
ND-330
F
ND-230
30–6,000
8.3–8,400
ND-150
ND-96
ND-250
F
F
F
F
F
F
F
81
20
F
F
F
F
F
F
F
F
F
F
120
43
F
F
F
F
F
7.1
F
F
F
F
260
103
F
F
F
ND-670
ND-1,100
ND-33
F
F
F
F
25–5,100
13–7,500
F
F
ND-240
F
F
F
F
F
F
F
99
30
F
F
F
F
F
F
F
F
F
F
150
58
F
F
F
F
F
9.1
F
F
F
F
300
170
F
F
F
ND-1,900
ND-2,600
ND-23
ND-3,400
ND-130
F
F
31–11,000
10–15,000
F
ND-700
ND-350
F F F
ND-5,700
F F F
ND-6,800
F F 29
ND-120
F F F
ND-3,400
F F F
ND-460
F F F
ND-1,700
F F F
ND-230
470 597 1,100 200–39,000
160 280 390 39–42,000
F F F
ND-150
F F F
ND-940
F F F
ND-1,100
35
20
F
F
2.3–120
ND-130
ND-56
ND-4,500
9.5
F
F
F
21
F
F
F
30
40
F
F
2.3–100
ND-280
ND-96
ND-5,400
6.5
F
F
F
14
F
F
F
22
6.7
F
F
ND-100
ND-56
ND-560
ND-4,500
11
F
F
F
22
F
F
F
34
28
F
F
2.6–78
ND-150
ND-69
ND-4,200
48
F
F
F
F F
F F
F F
F F
F F
F F
F F
98 190
42 59
F F
F F
F F
Other
Chlorthal-dimethyl 12
p, p’-DDE
F
p, p’-DDT
F
Iprodione
F
a
24
F
F
F
One section is missing for one subject for all analytes; trans-permethrin missing from one section of an additional subject’s section due to chromatographic interferences.
Range values reported consist of the composite data: bottom, top, arm and leg sections.
‘F’ and ND ¼ Nondetectable.
b
59 100
43 72
F 80
F F
80 120
34 180
F F
F F
Range
15–290
14–2,100
ND-1,300
ND-66
8.8–350
ND-500
ND-560
ND-19,000
Pesticides in Children’s Homes and Urine
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
p25 p50
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 5. Comparison of most frequently detected analytes (X90%) in union suits and socks by children’s age (n ¼ 20)a.
Union suits F composite (ng/sample)b,c
Socks (ng/sample)d
Analyte
n
Range
GM
Median
Ratioe
n
GM
Median
Ratioe
Chlorpyrifos
Crawling children
Toddlers
10
10
28–280
15–130
60
66
56
73
1.1
9
10
4.5–37
2.9–66
17
27
22
32
1.5
Chlorthal-dimethyl
Crawling children
Toddlers
10
10
8.8–300
16–350
53
84
68
91
1.6
9
10
1.8–26.0
6.8–200
9.5
29
16
28
3.0
Diazinon
Crawling children
Toddlers
10
10
14–130
20–2,100
39
66
41
43
1.7
9
10
3.6–29
0.0–590
8.1
24
7.0
15
2.9
cis-Permethrin
Crawling children
Toddlers
10
10
38–1,200
140–39,000
440
960
550
820
2.2
9
10
17–870
28–5,600
100
190
110
180
1.8
trans-Permethrinf
Crawling children
Toddlers
10
10
40–3,500
120–42,000
220
580
260
300
2.6
9
10
10–770
110–9,200
160
360
260
200
2.3
Range
a
Values below detection limit ¼ DL/O2.
Composite of all four union suit sections.
Data for one section of one toddler’s union suit is missing.
d
One crawling child’s sock sample is missing (n ¼ 9).
e
Ratio of geometric mean pesticide levels: Toddlers versus crawling children.
f
trans-Permethrin data for one section is missing for three toddlers.
Abbreviations: GM ¼ geometric mean.
b
c
samples were positively correlated for all children (r ¼ 0.57;
p ¼ 0.009).
Correlations Between Sampled Media
Table 6 presents Spearman correlations for the five most
frequently detected analytes across all the sampling media.
With the exception of chlorpyrifos, pesticides in house dust,
sock, and union suit samples were positively correlated and
had Spearman correlation coefficients ranging from 0.18 to
0.76 for the most frequently detected analytes (Table 6).
Indoor and outdoor air were moderately to strongly
correlated for diazinon, chlorpyrifos, and chlorthal-dimethyl.
Except for diazinon, levels on toys were not consistently
correlated with other media.
Correlations between diazinon and chlorpyrifos levels in
environmental media and overnight and spot urine diethyl
phosphate metabolite levels are also presented (see urine
methods, above). Except for toys (r ¼ 0.50; Po0.05), total
diethyl phosphate metabolites were weakly or negatively
correlated with levels of chlorpyrifos in other media (Table 6).
Total diethyl metabolites were positively correlated with
diazinon in house dust, socks, and union suits (r ¼ 0.069–
0.49; with overnight urine and dust significantly correlated,
Po0.05). Total diethyl phosphate metabolite levels were also
nonsignificantly associated with diazinon levels on toys
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
(r ¼ 0.20–0.33) (Table 6). We also evaluated the association
of total diethyl urinary metabolite levels with the molar sum
of diazinon and chlorpyrifos in each medium. Correlations
between these media and urine were generally weak
(r ¼ 0.17 to 0.24). Total diethyl metabolite levels in
overnight urine were moderately correlated with the molar
sum of diazinon and chlorpyrifos on toys (r ¼ 0.62;
Po0.05).
Child Activity Timeline and Recall Log
The majority of participating parents (B80%) understood
the Child Activity Timeline (CAT) and completed it
properly. In most cases, it took approximately 15 min to
explain the CAT to parents and to demonstrate filling it out,
and about 10 min to review it with the parents on the final
visit. Completing the Recall Log, however, appeared to be a
burden both to staff and to participating parents. The most
time-consuming components involved questions about the
specific surfaces contacted by the children and clothing worn
for each 30-min time interval. In most cases, parents were
unable to recall the amount of time the participating child
spent on each surface. This was particularly a problem for the
older, more active children.
Table 10 presents 24-h time activity and recall log
information for 10 crawling children and 10 toddlers. The
341
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 6. Spearman rank sum correlation matrix for the five most frequently detected analytes across sampling mediaa
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
Overnight urine
Spot urine
Chlorpyrifos
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
Overnight urine
Spot urine
1
0.25
0.24
0.14
0.36
0.16
0.087
0.24
0.39
1
0.54*
0.056
0.012
0.037
0.19
0.057
0.12
1
0.16
0.11
0.083
0.34
0.17
0.19
1
0.030
0.24
0.17
0.021
0.091
1
0.46*
0.44
0.14
0.089
1
0.11
0.17
0.31
1
0.50*
0.056
1
0.48*
1
Chlorthal-dimethyl
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
1
0.39
0.50*
0.053
0.63*
0.58*
0.075
1
0.76*
0.37
0.40
0.27
0.043
1
0.080
0.57*
0.56*
0.13
1
0.048
0.19
0.22
1
0.92*
0.23
1
0.12
Diazinon
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
Overnight urine
Spot urine
1
0.52*
0.47*
0.29
0.57*
0.24
0.33
0.49*
0.40
1
0.76*
0.25
0.52*
0.24
0.76*
0.25
0.11
1
0.16
0.55*
0.48*
0.52*
0.069
0.27
1
0.36
0.30
0.28
0.081
0.14
1
0.77*
0.59*
0.063
0.076
1
0.33
0.20
0.027
1
0.33
0.20
1
0.48*
1
cis-Permethrin
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
1
0.43
0.40
0.39
0.072
0.18
0.22
1
0.18
0.44
0.078
0.12
0.30
1
0.32
0.21
0.39
0.036
1
0.18
0.22
0.061
1
0.058
0.057
1
0.29
1
trans-Permethrin
Dust
Socks
Union suit
Surface wipe
Indoor air
Outdoor air
Toy
1
0.58*
0.52*
0.40
0.39
0.34
0.33
1
0.26
0.13
0.17
0.13
1
0.20
0.19
0.098
1
0.16
1
1
0.45
0.34
0.30
0.42
0.44
1
0.26
0.23
1
a
Spot and overnight urine samples are total diethyl phosphate metabolite levels (nmol/l). *Statistically significant Spearman rho (Po0.05).
children spent a large amount of time sleeping, with the
crawling children sleeping on average 12.6 h/day and the
toddlers sleeping on average 13.2 h/day. The crawling
children spent slightly more time eating than the toddlers
(mean ¼ 3.2 h/day versus 2.2 h/day, respectively). The
younger crawling children spent significantly more time in
quiet play compared to the toddlers (mean ¼ 5.0 h/day versus
342
1.4 h/day, respectively; t ¼ 3.4 Po0.05), while the toddlers
spent more time compared to the crawling children engaged
in active play (mean ¼ 4.4 h/day versus mean ¼ 1.7 h/day,
respectively; t ¼ 2.53 Po0.01). Further, the toddlers spent
significantly more time watching television than the crawling
children (mean ¼ 1.8 h/day versus 0.4 h/day, respectively;
t ¼ 3.3 Po0.01). All children spent most of their day inside
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Analyte
Organophosphorous pesticides
Acephate
Chlorpyrifos
Diazinon
Dimethoate
Isofenphos
Malathion
Methamidophos
Phosmet
Other
4,40 -DDD
4,40 -DDE
Atrazine
Dieldrin
Endosulfan
Nondetected analytes in food samplesc
Acetochlor (L ¼ 1.7/S ¼ 1.7)
a-Chlordane (L ¼ 1.8/S ¼ 1.8)
Alachlor (L ¼ 1.1/S ¼ 2.7)
Aldrin (L ¼ 5.5/S ¼ 2.0)
g-Chlordane (L ¼ 2.1/S ¼ 1.7)
Chlorothalonil (L ¼ 1.2/S ¼ 2.1)
Chlorpyrifos Oxon (L ¼ 1.6/S ¼ 2.0)
Combined food samples for crawling
children (ng/g) n ¼ 10
Liquid food samples
for toddlers (ng/g) n ¼ 9
Solid food samples
for toddlers (ng/g) n ¼ 10
Leftover handled food
samples (ng/g)b n ¼ 15
LOD (ng/g) (L, S)
Range
DF(%)
Range
DF(%)
Range
DF(%)
Range
DF(%)
0.50, 0.81
0.98, 1.4
0.58, 1.2
0.50, 0.81
1.0, 1.8
0.52, 1.6
0.61, 2.3
2.0, 1.9
F
o0.98–1.4
F
o0.50–0.88
F
o0.52–1.0
o0.61–0.80
o1.9–4.1
F
10
F
20
F
30
20
10
F
F
F
F
o0.50–1.4
F
o0.61–0.85
F
F
F
F
F
20
F
30
F
o0.81–1.0
F
F
o0.50–0.88
F
o1.6–7.8
o0.61–2.2
F
10
F
F
10
F
10
10
F
F
o0.98–1.0
o0.58–0.62
F
F
o0.52–1.8
o0.61–0.66
F
F
6.7
6.7
F
F
13
6.7
F
2.0, 4.6
3.5,1.8
3.9, 1.9
2.0, 1.5
6.1, 4.5
F
F
F
F
F
F
F
F
F
F
o2.0–5.3
F
F
F
F
10
F
F
F
F
F
F
o1.9–2.0
o1.5–4.8
F
F
F
10
10
F
F
o1.8–3.5
F
o1.5–6.1
o4.5, 5.1
F
6.7
F
6.7
6.7
Demeton O&S (L ¼ 1.0/S ¼ 2.1)
Dichlorvos (L ¼ 1.0/S ¼ 4.1)
Disulfoton (L ¼ 0.6/S ¼ 2.3)
Endrin (L ¼ 1.3/S ¼ 3.1)
Ethion (L ¼ 0.7/S ¼ 1.2)
Fenamiphos (L ¼ 0.7/S ¼ 1.2)
Fonofos (L ¼ 0.6/S ¼ 1.9)
Hexachlorobenzene (L ¼ 2.3/S ¼ 2.9)
Lindane (L ¼ 2.7/S ¼ 3.5)
Malathion Oxon 2 (L ¼ 0.8/S ¼ 2.2)
Methidathion (L ¼ 0.5/S ¼ 1.2
Methyl Parathion (L ¼ 0.6/S ¼ 2.0)
Metolachlor (L ¼ 1.1/S ¼ 1.7)
Mevinphos (L ¼ 0.7/S ¼ 2.0)
cis-Permethrin (L ¼ 6.5/S ¼ 4.5)
trans-Permethrin (L ¼ 3.0/S ¼ 2.9)
Parathion (L ¼ 0.6/S ¼ 1.2)
Phorate (L ¼ 1.3/S ¼ 2.1)
Simazine (L ¼ 6.4/S ¼ 3.5)
Trifluralin (L ¼ 1.1/S ¼ 4.2)
Vinclozolin (L ¼ 2.7/S ¼ 2.4)
Pesticides in Children’s Homes and Urine
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Table 7. Pesticide levels in children’s liquid, solid and combined food samples (n ¼ 20 children)a.
a
One participant had two liquid and two solid food samples and another participant had two liquid food samples: the second aliquot from each was not analyzed.
10 24-month olds and five 6-month olds had leftover handled food samples. Leftover handled foods are those that were liquid and/or solid leftover samples.
c
Numbers in parentheses represent the LOD of the liquid (L) and solid food (S) samples, respectively.
‘F’ ¼ Non detected.
b
A Bradman et al
343
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 8. Dialkyl phosphate metabolite levels in children’s spot and overnight urine samplesa.
Overnight Samples (nmol/l)b
Spot Samples (nmol/l)
Crawling children
n
GM
p25
p50
p75
Range
n
GM
p25
p50
p75
Range
Total diethyls
Total dimethyls
Total DAPs
10
10
10
16
71
117
1.3
8.9
37
24
110
130
41
250
450
1.3–240
4.1–1,100
5.4–1,300
10
10
10
4.6
52
71
1.3
5.9
15
2.7
81
84
13
230
230
1.3–65
4.1–4,400
5.4–4,400
Toddlers
Total diethyls
Total dimethyls
Total DAPs
10
10
10
8.0
62
83
1.3
12
14
4.5
81
100
46
220
330
1.3–310
7.0–1,100
8.3–1,100
10
10
10
4.3
102
120
1.3
89
91
1.3
130
180
11
250
350
1.3–210
4.1–400
5.4–440
All children
Total diethyls
Total dimethyls
Total DAPs
20
20
20
11
66
99
1.3
11
32
13
85
100
44
240
390
1.3–310
4.1–1,100
5.4–1,300
20
20
20
4.4
73
92
1.3
11
18
1.3
130
140
12
240
310
1.3–210
4.1–4,400
5.4–4,400
Creatinine (mg/dL)
20
31
16
28
60
7.6–150
20
37
22
40
57
13–120
a
Values below detection limit ¼ DL/O2, consistent with NHANES data published by CDC (CDC, 2003).
One toddler is missing an overnight sample DMTP measurement; thus, total dimethyl and DAP metabolite concentrations were imputed for that child (see
Methods).
Notes: Detection limits and detection frequencies (%) for urinary metabolite data: DMP ¼ 0.4 mg/l (46.2); DMTP ¼ 0.3 mg/l (82.1); DMDTP ¼ 0.08 mg/l
(33.3); DEP ¼ 0.1 mg/l (38.5); DETP ¼ 0.1 mg/l (43.6); DEDTP ¼ 0.1 mg/l (2.6).
b
Table 9. Spearman ‘‘r’’ correlation between spot and overnight urine
samplesa.
Diethyl phosphate
Dimethyl phosphate
n
P-value
n
r
P-value
0.22
10
0.60
0.07
10 0.66 0.04
0.16
0.03
10
20
0.53
0.53
0.12
0.02
10 0.65 0.04
20 0.57 0.009
Age group
r
Crawling
10 0.43
children
Toddlers
10 0.48
All children 20 0.48
Total DAP
n
r
P-value
a
One toddler is missing an overnight sample DMTP measurement; thus
total dimethyl and DAP metabolite concentrations were imputed for that
child (see Methods).
the home (mean ¼ 21.3 h/day) compared to outside in the
yard (mean ¼ 0.9 h/day) or away from home (1.8 h/day).
Discussion
We collected multimedia exposure samples from the homes of
20 farmworker children living in the Salinas Valley, CA, an
agricultural region. Measurable levels of OP, OC, and
pyrethroid pesticides were detected in house dust, indoor
and outdoor air, surface wipes, clothing, and food. The
pesticides chlorpyrifos, diazinon, cis- and trans-permethrin,
and chlorthal-dimethyl were commonly detected in most
media. Pesticide residues on clothing (union suits and socks)
were consistently higher in the older group of children (21–27
months) compared to the younger children (5–11 months).
344
In addition, spot and overnight diaper urine samples were
collected successfully and analyzed for DAP metabolites. We
found measurable levels of DAP metabolites in all the
children’s urine. DAP metabolites in spot and overnight
diaper samples were correlated (rB0.6), suggesting that spot
urine samples may be valid indicators of total daily
metabolite excretion.
The greatest number and type of pesticides were detected
in house dust, surface wipes, and clothing compared to other
environmental media. Thus, these media may be the best
indicators of which pesticides are present in a given home.
Detectable levels of pesticides were measured on ageappropriate toys distributed just a few days before the home
sampling visit, demonstrating that pesticides can quickly
transfer to toys that are handled and explored orally by
children. While the levels of pesticides in dust and clothing
were only moderately correlated (Table 6), the presence or
absence of a pesticide in one medium generally indicated the
presence or absence in the other medium.
Higher concentrations of the most frequently detected
analytes on the clothing of the older age group may be
attributed to the fact that toddlers are more actively walking,
running, crawling, and playing than younger children, and
are thus potentially more exposed to pesticide residues from
residential surfaces. This hypothesis is supported by the
higher DAP metabolite levels in older children (Table 8);
however, the older children’s exposures may be due, in part,
to differences in diet.
This study is the first to report data on a broad range of
pyrethroid pesticides in the home environments of children.
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Pesticides in Children’s Homes and Urine
A Bradman et al
Table 10. 24 h time activity information for crawling children and
toddlers (n ¼ 20).
Hours spent per activity
Table 11. Usage in the Salinas Valley (2002)a of pesticides frequently
detected in multimedia samples.
Pesticide
Mean (SD)
Chlorpyrifosb
Diazinonb
Permethrinc,d
Chlorthal-dimethyle
Total
Kilograms applied in 2002
23,576
65,127
11,365
32,865
132,933
Activity
N
Range
Sleeping
Crawling children
Toddlers
10
10
10.5–15
10–19
Eating
Crawling children
Toddlers
10
10
0–5
1–5
3.2 (1.4)
2.2 (1.2)
Other:
Acephatef
Dimethoateg
31,471
15,905
Quiet play
Crawling children
Toddlers
10
10
1–10
0–4
5.0 (2.9)
1.4 (1.6)
Dieldrin
Iprodione
Malathiong
Phosmetg
0
23,349
39,713
1,463
Active play
Crawling children
Toddlers
10
10
0–6.5
0–8.5
1.7 (2.4)
4.4 (2.3)
Watching TV
Crawling children
Toddlers
10
10
0–1.5
0–4.5
0.4 (0.6)
1.8 (1.2)
Sitting in a stroller or car seat
Crawling children
10
Toddlers
10
0–3.5
0–4.5
1.2 (1.2)
1.1 (1.4)
12.6 (1.5)
13.2 (2.3)
Inside home
Crawling children
Toddlers
10
10
Outside home
Crawling children
Toddlers
10
10
0–2
0–2.5
0.6 (0.8)
1.2 (0.9)
Away from home
Crawling children
Toddlers
10
10
0–9.5
0–7.5
1.9 (3.2)
1.7 (2.2)
14.5–24
16.5–23.5
21.6 (3.1)
21.1 (2.2)
Consistent with the low vapor pressure of pyrethroids,
relatively low levels of these compounds were detected in air.
The pyrethroids cis- and trans-permethrin were, however, the
most frequently detected pesticides in dust and clothing and
were also present at the highest levels. Our findings reflect the
increasing use of pyrethroid pesticides in home environments
as manufacturers substitute these materials for restricted-use
OP pesticides (DPR, 2004). Other studies in the US (Colt
et al., 2004) and other countries have found permethrins to
be the most abundant pesticides routinely detected in dust
(Butte and Heinzow, 2002).
Chlorpyrifos and diazinon were detected in all of the
sampling media. These compounds may persist longer in
indoor environments compared to outdoor environments due
to the lack of sunlight, moisture, and soil microorganisms
(Lewis et al., 1994) and have been detected in many studies
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
a
Includes agricultural, landscape maintenance, structural pest control and
roadside pesticide usage; agriculture represents 99% of total use (DPR
2001).
b
Diethyl OP pesticide.
c
Quantities of cis- and trans-permethrins are combined.
d
Pyrethroid pesticide.
e
Herbicide.
f
OP pesticide that does not devolve to DAP urinary metabolites.
g
Dimethyl OP pesticide.
of home environments (Butte and Heinzow, 2002; Colt et al.,
2004; Egeghy et al. 2005). Chlorpyrifos and diazinon are no
longer licensed for home pesticide use (U.S. EPA, 2000,
2001) and no participants reported using these pesticides.
The residues we found may be due to previous home use or
local agricultural pesticide use.
We detected chlorthal-dimethyl in all house dust, indoor
air, outdoor air, surface wipe, union suit, and some toy
samples. Chlorthal-dimethyl is a semi-volatile chlorinated
phthalate herbicide used primarily in agriculture (the parent
product is known as Dacthal). Chlorthal-dimethyl has an
estimated half-life of 36 days in air (HSDB, 2005) and is
commonly present in the air of agricultural valleys in
California (Ross et al. 1990; USGS, 2002) and elsewhere
(Rawn and Muir, 1999), and in the soil and sediment in
Monterey County (DPR, 1988). Chlorthal-dimethyl has also
been detected in air samples taken from a region with low
agricultural and home pesticide use (Whitmore et al., 1994),
suggesting the potential for long-range transport (Rawn and
Muir, 1999). It has also been detected in the dust of farmers’
homes and, at lower levels, in control homes (Starr et al.,
1974).
Of the five commonly detected analytes, only cis- and
trans-permethrin and chlorthal-dimethyl are licensed for use
in and around the home. In this population, however, home
use of these pesticides was rarely or never reported. Table 11
summarizes possible sources of these contaminants, including
agricultural, landscape maintenance, structural pest control,
and roadside pesticide use in the Salinas Valley (DPR, 2002).
345
A Bradman et al
Duplicate diet and surface press samples were less
promising methods of assessing pesticide exposure in this
study. Pesticides were not detected in any of the surface press
samples. As shown recently (Cohen Hubal et al., 2005),
transfer efficiencies of chlorpyrifos and allethrin from
carpeted and laminate surfaces to the C18 Press Sampler
are quite low, on the order of 0.01–0.55%. While other
studies have suggested that food ingestion may be one of the
major routes of children’s exposure to pesticides (Clayton
et al., 2003; Wilson et al., 2003), we were not able to
adequately assess the relative importance of diet as a route of
exposure. Owing to the small volume sampled and relatively
high limits of detection, analyte detection frequencies in food
samples were low compared to those found in the environmental and clothing samples. The limits of detection for
chlorpyrifos and dieldrin reported by Wilson et al. (2003)
were almost two orders of magnitude lower than those in this
study (0.04 versus 1 and 2 ng/g, respectively). These detection
limits, however, may not be directly comparable because they
were not calculated in the same manner (i.e., detection limits
based on signal to noise ratios versus detection limits based
on spiked matrix replicates).
We developed four field survey instruments (questionnaire,
home inspection, food diary, and CAT/recall log) to help
characterize children’s pesticide exposure pathways. These
instruments were well received by the participating families as
well as by study staff. In general, the CAT was easy to use
and consumed little time. Providing extensive instruction and
training to parents gave them confidence in completing the
form and improved the quality and reliability of the
information attained. A surprising finding based on the
CAT data was that all the children in the study spent most of
their day inside the home (mean ¼ 21.3 h/day) compared to
outside in the yard (mean ¼ 0.9 h/day) or away from home
(1.8 h/day). However, this is consistent with the quality of
participants’ housing, which was generally small and
crowded with little or no yard space.
For future studies, we recommend that the CAT be
divided to cover shorter time periods (i.e., six instead
of 12 h), presented on several sheets to make it less
visually crowded, and modified to provide a more complete
list of age-specific activities and common locations (e.g., time
in daycare, time at school for older children, etc.). In
contrast to the CAT, the Recall Log was difficult and timeconsuming to complete. Specifically, use of the Recall
Log to collect additional information not recorded on the
CAT, such as spent on different surface types and clothing
worn, was tedious and may have contributed to errors by
study staff when coding responses. The Recall Log should be
simplified to directly mirror the CAT for all data collected.
Finally, it is unlikely that resolution of data about which
room the child was in and clothing worn is feasible for time
increments less than 30 or 60 min, especially for older
children.
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Pesticides in Children’s Homes and Urine
Urinary DAP metabolite concentrations reported in this
study were similar to levels found in other children. For
example, children ages 2–5 living in an agricultural community of Washington State had geometric mean urinary
metabolite levels for diethyl and dimethyl phosphates of 36
and 80 nmol/l, respectively (Koch et al., 2002). In another
study of Washington children living in an agricultural area,
spot urine samples collected from farmworker children ages
2–6 years had median levels of diethyl and dimethyl
phosphate metabolites of 60 and 80 nmol/l, respectively
(Curl et al., 2002). Finally, median total DAP levels in spot
urine samples for our population of 5–27 month old children
were similar to NHANES levels for children 6–11 years old
(median ¼ 113 nmol/l)(Barr et al. 2004). These populations
are not directly comparable, however, due to the differences
in their ages.
Dimethyl phosphate metabolite levels were higher than
diethyl phosphate metabolites, a finding consistent with
previous studies in other populations (Koch et al., 2002; Barr
et al., 2004). The molar ratio of dimethyl to diethyl
metabolites in the participants’ urine was 8:1, which is higher
than would be expected given the 3:2 ratio of dimethyl (e.g.,
malathion) to diethyl (e.g., chlorpyrifos) OP pesticides that is
typically used in the Salinas Valley (DPR, 2001, 2002). The
discrepancy may be explained by alternate exposure pathways, such as diet and home pesticide use. It is also possible
that diethyl pesticides and metabolites degrade more rapidly
than dimethyl OP pesticides. This hypothesis is supported by
our finding that diethyl phosphates were lower in overnight
diaper samples than in spot samples.
We did not observe strong correlations between diethyl
phosphate urinary metabolites and levels of diazinon and
chlorpyrifos, which devolve to these metabolites, in environmental and personal media. The correlations we do report,
although weak to moderate, tended to be more consistent for
diazinon compared to chlorpyrifos or the molar sum of
diazinon and chlorpyrifos. We have no ready explanation for
this finding. It is possible that diazinon in the home
environment is more likely to be absorbed, inhaled, or
ingested by a child. The overall lack of strong correlations
may be due to high variability in the environmental or
urinary measurements that would obscure meaningful
associations, especially given the small sample size. It is also
possible that the diethyl metabolites in the children were due
to exposures to other diethyl phosphate metabolites in the
environment or diethyl OP pesticides, which are used locally
in agriculture. In the future, we intend to measure pesticidespecific metabolites to, at least partially, address this
possibility. Finally, one recent study found that diet is the
primary source of children’s OP pesticide exposure (Lu et al.,
2005), suggesting that environmental concentrations may not
be associated with exposure biomarkers.
This study has several limitations. First, the study had a
small sample size and took place in an agricultural region;
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
Pesticides in Children’s Homes and Urine
thus observed pesticide exposures cannot be generalized to a
larger agricultural or general population. Additionally, the
relatively low sensitivity of our analytical methods for food
may have reduced the detection frequencies of some
pesticides. Future studies using clothing samples should use
100% polyester union suits to avoid the formation of
gelatinous flocculates. The flocculate appears to be organic
material extracted from the cotton fibers, and thus washing
and/or pre-extraction will not reduce this material to an
acceptable level. In subsequent work, we have found that
extraction of 100% polyester union suits does not yield this
flocculate.
We provide unique data on the likely range of pesticide
exposures to young children living in an agricultural
community and how exposures may differ due to age. The
presence of permethrins, chlorpyrifos, diazinon, and
chlorthal-dimethyl in most environmental samples suggests
that these compounds were ubiquitous in the homes and
further research is needed on the environmental fate of these
compounds.
In future analyses, we will explore potential relationships
between pesticide exposure factors, based on questionnaire,
child activity, and home inspection data, and specific and
nonspecific urinary OP metabolites. We will also focus on
apportioning routes of exposure and estimating relative
contributions of exposure media. Additionally, a pesticide
exposure model is currently being developed to determine the
behavior and activity patterns of children resulting in dermal
and nondietary exposure from pesticide residues on surfaces
in and around the home environment. These data and models
will be used to characterize and assess aggregate exposure in
children and to develop exposure and risk assessment models.
Acknowledgements
The United States Environmental Protection Agency
through its Office of Research and Development partially
funded and collaborated in the research described here under
RD 83171001 to the U.C. Berkeley Center for Children’s
Environmental Health Research. It has been subjected to
Agency review and approved for publication. This research
was also funded by NIEHS grant PO1 ES009605. Its
contents are solely the responsibility of the authors and do
not necessarily represent the official views of the funding
agencies. T. McKone was supported in part by the U.S. EPA
National Exposure Research Laboratory through Interagency Agreement DW-988-38190-01-0 with Lawrence Berkeley National Laboratory through the US Department of
Energy under Contract Grant No. DE-AC02-05CH11231.
The authors declare they have no competing financial
interests. We gratefully acknowledge Katherine Kogut for
her technical assistance, the field staff, and, especially, the
families that participated in this study for their valuable time
and commitment.
Journal of Exposure Science and Environmental Epidemiology (2007) 17(4)
A Bradman et al
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