The EPA National Exposure Research Laboratory Children's Pesticide
Exposure Measurement Program
RC Fortmann1, LS Sheldon, EA Cohen Hubal, MK Morgan, DM Stout, II, KW Thomas, NS
Tulve, and DA Whitaker
Human Exposure and Atmospheric Sciences Division, National Exposure Research
Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC,
USA
ABSTRACT
The U.S. Environmental Protection Agency (EPA) National Exposure Research
Laboratory (NERL) is performing research in support of the Food Quality Protection Act
(FQPA) of 1996. This act requires that pesticide exposure assessments to be conducted for all
potential sources, routes and pathways, not just dietary intake. The goal of the NERL
program is to develop and evaluate protocols and methods for assessing children's aggregate
and cumulative exposures to pesticides, and to collect data required to reduce the reliance on
default assumptions in development of quantitative exposure assessments. This paper
provides an overview of the framework and approach for the research program and
descriptions of studies being performed to fill data gaps in the following areas:
•	Spatial and temporal distribution of pesticide residues indoors,
•	Pesticide use patterns indoors,
•	Dermal exposure,
•	Indirect ingestion exposure,
•	Microenvironments and macroactivity patterns of children, and
•	Children's exposure measurements protocols and methods.
INDEX TERMS
Pesticides, Children, Human Exposure, Food Quality Protection Act
INTRODUCTION AND BACKGROUND
The U.S. EPA has pledged to increase its efforts to provide a safe and healthy
environment for children by ensuring that all EPA regulations, standards, policies, and risk
assessments take into account special childhood vulnerabilities to environmental toxicants.
Children's exposures to environmental contaminants are expected to be different and, in many
cases, much higher than older individuals due to differences in behavioral patterns and
physiological functions (Bearer, 1995). Children's activities and the way that they interact
with their environment may have a profound effect on the magnitude of their chemical
exposures. They may crawl, roll, and lie on contaminated surfaces. Children's mouthing
activities (hand-to-mouth and object-to-mouth) may result in indirect ingestion of chemicals if
the hands or objects are contaminated. Indirect ingestion of contaminants may also occur
when children handle and eat foods that have come in contact with the floor or other
contaminated surfaces.
In order to articulate the problems and research needs associated with children's
exposure to environmental pollutants, the EPA Office of Research and Development (ORD)
1 E-mail: Fortmann.roy@epa.gov

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developed the Strategy for Research on Environmental Risks to Children (U.S. EPA, 2000).
Within the Children's Risk Strategy, three specific objectives have been formulated to (1)
make use of existing information to develop improved risk assessment methods and models
for children; (2) design and conduct research on exposure, effects, and dose-response that will
answer questions about age-related differences in exposure and risks and that will lead to
better risk assessments for children; and (3) explore opportunities for prevention and
reduction of risks to children. The NERL children's exposure research program is designed to
address these objectives.
The ORD is conducting research related to children's exposure in support of the Food
Quality Protection Act (FQPA) of 1996. FQPA requires EPA to upgrade the risk assessment
procedures for setting pesticide residue tolerances in food by considering the potential
susceptibility of infants and children to both aggregate and cumulative exposures to
pesticides. Aggregate exposures include exposures from all sources, routes and pathways for
individual pesticides. Cumulative exposures include aggregate exposures to multiple
pesticides with the same mode of action for toxicity. Very importantly, FQPA requires that
risk assessments must be based on exposure data that are of high quality and high quantity or
exposure models using factors that are based on existing, reliable data.
A comprehensive approach is required to understand and adequately address all of the
components of aggregate and cumulative exposure assessments. To develop NERL's research
strategy and approach, factors influencing children's exposure to environmental contaminants
were reviewed and the quality and quantity of available data associated with default
assumptions for exposure factors were evaluated (Cohen Hubal et al., 2000a). A framework
to systematically identify the important sources, routes, and pathways for exposure was
developed (Cohen Hubal et al., 2000b). This framework is based upon the development of a
conceptual model for aggregate exposure and provides the basis for developing a protocol to
measure and assess aggregate exposures, as well as for developing sophisticated stochastic
models. This framework also allows researchers to systematically identify the most critical
research needs and data gaps associated with children's exposures to pesticides.
A conceptual model of children's residential exposure to pesticides was developed that
was the initial focal point for the children's pesticide exposure research strategy and
development of measurement studies and protocols (Cohen Hubal et al., 2000b). NERL
researchers used the model to identify important routes and pathways of exposure and to
identify four priority research areas that included the following:
•	Pesticide use patterns - what, where, and how are pesticides used in children's
microenvironments,
•	Spatial and temporal distribution of pesticides in residential dwellings,
•	Dermal and indirect (non-dietary) ingestion - need to develop measurement
approaches (microactivity or macroactivity approaches), and
•	Dietary exposure assessments, to include indirect ingestion due to the handling
of food by children.
STUDIES TO ADDRESS PRIORITY RESEARCH AREAS
To address these research needs, targeted studies, described below, were designed.
They included laboratory studies, small pilot field studies, and two large studies in which the
EPA collaborated with other Federal agencies, as described below.

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Children's Total Exposure to Persistent Pesticides and Other Persistent Organic
Pollutants (CTEPP)
The CTEPP study is the largest children's exposure study undertaken to date. It
examines the aggregate exposures of 257 preschool children between the ages of 18 months
and 5 years to pollutants commonly found in their everyday environments. The major
objectives of this three-year pilot study were to quantify children's aggregate exposures,
apportion the exposure pathways, identify the important exposure media, and formulate the
important hypotheses for future testing. Participants were recruited from daycare centers and
from the general population in twelve urban and rural counties in North Carolina and Ohio
using a random digit dialing (RDD) method. Monitoring was performed during 48-hour
sampling periods at both daycare centers and homes. Samples collected include food,
beverages, drinking water, indoor air, outdoor air, hand wipes, indoor floor dust, play area
soil, transferable pesticide residues, floor wipes, food preparation surface wipes, and urine.
The samples are being analyzed for over 40 persistent pesticides and organic pollutants,
including herbicides (atrazine), insecticides (organophosphorus, carbamate, pyrethrin and
organochlorine), phthalate esters (butylbenzyl, di-n-butyl), phenols, polychlorinated
biphenyls, and polycyclic aromatic hydrocarbons. Sample analysis will be completed and
preliminary results will be reported this year.
Study to Identify Important Parameters for Characterizing Pesticide Residue Transfer
Efficiencies
The objective of this laboratory study is to evaluate parameters that affect pesticide
residue transfer from surface-to-skin, skin-to-objects, skin-to-mouth, and object-to-mouth.
The approach is to use fluorescent tracers as surrogates for pesticide residues. Transfers of
riboflavin, the tracer in the initial tests, were compared to transfers of chlorpyrifos and
bioallethrin. Following application of the tracers to realistic surfaces (e.g., carpet, laminate),
controlled transfer experiments were conducted to evaluate parameters that included the
surface type, surface loading, type of contact (press versus smudge), contact duration, contact
pressure, and skin condition (dry, moist, or sticky). The study involved tests to evaluate
repetitive contacts with contaminated surfaces, measurements of transfers off the skin, and
simulated mouthing removal using saliva moistened PUF. Surface loading, skin condition,
and surface type were significant parameters in the initial tests. In the second phase of this
study, additional tracers and pesticides with a range of physiochemical properties will be
evaluated. Controlled transfer experiments will be performed to refine the understanding of
significant parameters and to develop a more comprehensive set of transfer efficiency data
that can be used to predict dermal and indirect ingestion exposure from field measurements.
Feasibility of Using the Macroactivity Approach to Assess Dermal Exposure
Two main approaches are currently used to assess dermal exposure. In the
macroactivity approach, exposure is estimated for each macroactivity that the child conducts
within each microenvironment (e.g. quiet play in the living room, active play in the kitchen).
With this approach, exposure is estimated using empirically derived transfer coefficients to
aggregate the mass transfer associated with a series of contacts with a contaminated medium.
In the microactivity approach, exposure is explicitly modeled as a series of discrete transfers
resulting from each contact with a contaminated medium. With this approach, exposure must
be estimated for all contacts made by child during a 24-hour period. The objective of this
study is to test the feasibility of the macroactivity approach to assess children's dermal
exposure to pesticides in daycare centers. Screening measurements were performed in nine
daycares where pesticides were applied as crack and crevice treatments by commercial
applicators. At one daycare, children were asked to wear full-body cotton dosimeters for short

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time periods while involved in selected macroactivities (e.g., storytime, playtime indoors).
Surface sampling of pesticide residues and videotaping of activities were performed
simultaneously. Sample analysis is ongoing. Results will be used to calculate transfer
coefficients and to evaluate this approach for estimating dermal exposure.
Post-Application Exposure Studies
Researchers in NERL are involved in two post-application studies. In both studies,
aggregate exposure measurements were made following a crack and crevice application by a
professional applicator. Objectives of these studies include development of dermal transfer
coefficients for young children engaged in specific activities and evaluation of the
macroactivity approach. In a collaborative study with researchers at the Environmental and
Occupational Health Sciences Institute (EOSHI), aggregate exposure measurements were
made at nine residences following a professional chlorpyrifos crack and crevice application.
Measurements included indoor air, air exchange rates, surface residue wipes, dust wipes, toy
wipes, dermal wipes (hands and knees), activity diary, videotaping, cotton dosimeters, and
urine. Surface loadings of chlorpyrifos ranged from 0.002 to 0.12 ng/cm2 based on wipe
measurements and transfer coefficients ranged from 300 to 84,000 cm2/hr. Results of the
study showed that pesticide loadings in the cotton dosimeters were related to exposure
duration, surface loading, activity level and type of surface, suggesting that the macroactivity
approach may be useful for estimating children's dermal exposure. The second post-
application exposure study, being conducted in nine homes in North Carolina, complements
the first study. The objectives and methods for this study are similar. This study, however,
addresses potential exposures following residential crack and crevice applications of synthetic
pyrethroid pesticides, the most commonly used indoor pesticides since the discontinuation of
indoor uses of chlorpyrifos and diazinon. This study is ongoing.
First National Environmental Health Survey of Child Care Centers
EPA's objective in this collaborative study with the Department of Housing and Urban
Development (HUD) and the Consumer Product Safety Commission (CPSC) is to collect
information on pesticide use and pesticide distributions in child care centers. Licensed
institutional childcare centers were randomly selected for participation in this national study.
The study design used multi-stage sampling with clustering to select approximately 150
childcare centers in 30 primary sampling units in the United States. Samples were collected
for pesticides, lead, and allergens at multiple indoor locations in each child care center. Soil
samples were also collected near a play area at each center. Pesticide use practices and
application information were obtained from the commercial pest control applicators serving
the centers. In this study, the EPA will gain a better understanding of pesticide use and young
children's (less than 6 years old) potential exposure to pesticides in institutional childcare
centers. The field data collection has been completed; sample analysis is ongoing.
Characterizing Children's Pesticide Exposures in Jacksonville, Florida
The Duval County, Florida Health Department with collaboration by the Centers for
Disease Control and Prevention (CDC) and the EPA is conducting a research study to
measure pesticide exposure in a sample of children in Jacksonville, FL. The objectives of the
project are to (1) assess organophosphate (OP) pesticide and pyrethroid pesticide exposures in
a group of 4-6 year old children from urban, rural, and suburban Jacksonville by measuring
the urine metabolite levels of OPs and pyrethroids, (2) identify possible sources of these
pesticides in homes by performing screening measurements and pesticide inventories, and (3)
examine the relationship between environmental levels of OP and pyrethroid pesticides and
biological levels. For this study, the Duval County Health Department (DCHD) collected

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urine samples from 200 children visiting six public health clinics in Jacksonville, Florida.
The CDC will perform analyses of these samples for OP and pyrethroid pesticide metabolites.
In a second component of the study, DCHD staff collected environmental screening samples
at approximately 25% of these children's homes. The third component of the study,
performed by the EPA with assistance from DCHD, involved a detailed aggregate exposure
assessment at nine of the study homes. The assessment involved collection of surface wipes,
transferable residues, air, duplicate diet, cotton dosimetry samples, and urine samples. A time
activity diary of the children's activities was completed. The field study has been completed
and sample analysis is ongoing. Results of the pesticide inventory showed that synthetic
pyrethroids were the primary pesticides used in the residences in addition to gels and baits
containing hydramethylnon and fipronil.
Study to Evaluate the Potential for Human Exposure to Pet-borne Diazinon Residues
Following Residential Turf Applications
The objectives of this exposure measurement study are to investigate the potential for
indoor/outdoor pet dogs to transport diazinon residues into homes following residential turf
application. The study was performed at six homes in North Carolina where a homeowner
made a single application of a granular diazinon formulation to turf. Samples were collected
at pre-application and at 1,2, 4, and 8 days post-application. Environmental samples were
collected to determine the mass of diazinon applied to the lawn, the movement of residues
into the structure, and the spatial and temporal distribution following the application.
Residues were measured in samples from the fur, paws and blood of the family dog and from
the hands and urine of a child in each home. The study also included videotaping of the child
playing with the dog and collection of transferable residues by petting the dog with cotton
gloves. The field measurements have been completed; sample analysis is ongoing. In the pre-
test for this study, results from one residence showed that diazinon was transferable from
treated turf through 15 days and intruded into the dwelling through the air and by track-in
(Morgan, et al., 2001). Analysis of fur clippings, and fur and paw wipes from the family's dog
suggested that it served as an important medium for the uptake of turf transferable residues.
The Distribution of Chlorpyrifos Following a Crack and Crevice Type Application in
the U.S. EPA Indoor Air Quality Test House
The primary objective of this study was to examine the spatial and temporal
distributions of the insecticide chlorpyrifos following, a crack and crevice application in the
EPA Indoor Air Quality Test House located in Cary, NC. Measurements during the 18-day
study included air concentrations using both polyurethane foam (PUF) and OVS samplers,
surface transferable residues using the PUF roller, surface concentrations (loadings)
employing deposition coupons and extractable residues from carpet. Results of the study are
in a paper (Stout and Mason, 2002) presented at this conference.
Other EPA Children's Exposure Measurement Studies
In addition to the studies support of the FQPA described in this paper, there are a
number of other recently completed or ongoing measurement studies involving NERL
researchers that address children's exposure to environmental contaminants. The National
Human Exposure Assessment Survey (NHEXAS) Region 5 study, for example, included the
Minnesota Children's Pesticide Exposure Study (MNCPES). The study obtained pesticide
(chlorpyrifos, diazinon, malathion, and atrazine) data for 102 children, including
measurements of personal exposure (air, hand rinse, duplicate diet), activity patterns
(questionnaire, diary, and videotaping), environmental concentrations (indoor and outdoor air,
surface residues, drinking water, soil), and metabolites in urine (Quackenboss et al., 2000;

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Adgate et al., 2001). The Arizona NHEXAS study also included multi-media measurements
of pesticides in households with children (Robertson et al., 1999). Pesticide exposures in
young children along the US/Mexico border, are being addressed in a number of studies
(referred to as the NAFTA border studies) that are described on the U.S.-Mexico Border XXI
Environmental Health Workgroup web site (www.epa.gov/orsearth/proiects.htm).
A number of other children's exposure studies are being funded, or co-funded, by EPA
through cooperative agreements and grants. Information on many of the current studies is
available through various EPA web sites, including the Children's Environmental Health and
Safety Inventory of Research site (http://oaspub.epa.gov/chehsir/chehsir.page). the ORD
National Center for Research (NCER) web site (www.epa.gov/ncer). and the ORD/NERL site
(www.epa.gov/nerl).
U.S. EPA Disclaimer
This paper has been reviewed in accordance with the United States Environmental
Protection Agency's peer and administrative review policies and approved for presentation
and publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
REFERENCES
Adgate JL, Barr DB, Clayton CA, Eberly LE, Freeman NCG, Lioy PJ, Needham LL,
Pellizzari ED, Kukowski A, Quackenboss JJ, Roy A, and Sexton K. 2001. Measurement
of children's exposure to pesticides: Analysis of urinary metabolite levels in a probability-
based sample, Environ. Health Perspect. 109(6):583-590.
Bearer CF. 1995. How are children different from adults? Environ. Health Perspect.
103(Suppl 6):7-12.
Cohen Hubal EA, Sheldon LS, Burke JM, McCurdy TR, Berry MR, Rigas ML, Zartarian VG,
and Freeman NCG. 2000a. Children's exposure assessment: A review of factors
influencing children's exposure, and the data available to characterize and assess that
exposure, Environ. Health Perspect. 108:475-486.
Cohen Hubal EA, Sheldon LS, Zufall MJ, Burke JM, and Thomas KW. 2000b. The challenge
of assessing children's exposure to pesticides, J. Expo. Anal. Environ. Epidemiol.\0:63B-
649.
Morgan MK, Stout II DM and Wilson NK. 2001. A feasibility study of the potential for
human exposure to pet-borne diazinon residues following lawn applications, Bull.
Environ. Contam. & Toxicol. 66(3):295-300.
Quackenboss JJ, Pellizzari ED, Shubat P, Whitmore RW, Adgate JL, Thomas KW, Freeman
NC, Stroebel C, Lioy PJ, Clayton CA, Sexton K. 2000. Design strategy for assessing
multi-pathway exposure for children: the Minnesota Children's Pesticide Exposure Study
(MNCPES), J Expo Anal Environ Epidemiol. 10(2): 145-158.
Robertson GL, Lebowitz MD, O'Rourke MK, Gordon S, and Moschandreas D. 1999. National
Human Exposure Assessment Survey (NHEXAS) study in Arizona-introduction and
preliminary results, J Expo Anal Environ Epidemiol. 9(5):427-434.
Stout DM, II and Mason MA. 2002. The distribution of chlorpyrifos following a crack and
crevice type application in the U.S. EPA Indoor Air Quality Test House, Proceedings,
Indoor Air 2002.
U.S. EPA. 2000. Strategy for Research on Environmental Risks to Children. Office of
Research and Development, Washington, D.C. EPA/600/R-00/068, August, 2000.
http://www.epa.gov/neea/risk2kids.htm

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ATTACHMENT 3
NIRL-RTP-Heasd-02—005 TECHNICAL REPORT DATA
1. REPORT NO.
F.PA /600 / A-02 /032
2 .
3.R
4. TITLE AND SUBTITLE
The EPA National Exposure Research Laboratory Children's Pesticide
Exposure Measurement Program
5.REPORT DATE
6. PERFORMING ORGANIZATION CODE
7. AUTHOR!SS
Fortmann, R.C., Sheldon L.S., Cohen Hubal E.A., Morgan, M.K., Stout, D.M.
II, Thomas, K.S., Tulve, N.S., and Whitaker, D.A.
8.PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Human Exposure Analysis Branch/Human Exposure and Atmospheric
Sciences Division/National Exposure Research Laboratory, US EPA, MD-56,
Research Triangle Park, NC 27711
10,PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12 SPONSORING AGENCY NAME AND ADDRESS
National Exposure Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13.TYPE OF REPORT AND PERIOD COVERED
Conference Proceedings (peer-reviewed)
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The U.S. Environmental Protection Agency (EPA) National Exposure Research Laboratory (NERL) is performing
research in support of the Food Quality Protection Act (FQPA) of 1996, which requires that pesticide exposure assessments to
be conducted for all potential sources, routes and pathways, not just dietary intake. The goal of the NERL program is to develop
and evaluate protocols and methods for assessing children's aggregate and cumulative exposures to pesticides, and to collect data
required to reduce the reliance on default assumptions in development of quantitative exposure assessments. This paper provides
an overview of the framework and technical approach for the research program and descriptions of studies being performed to
fill data gaps in the following areas:
•	Spatial and temporal distribution of pesticide residues indoors,
•	Pesticide use patterns indoors,
•	Dermal exposure,
•	Indirect ingestion exposure,
•	Microenvironments and macroactivity patterns of children, and
•	Children's exposure measurements protocols and methods.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
^IDENTIFIERS/ OPEN ENDED
TERMS
c.COSATI
Pesticides, children, human exposure, Food Quality
Protection Act


18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC

19. SECURITY CLASS (This Report)
UNCLASSIFIED
21.NO. OF PAGES

20. SECURITY CLASS (This Page)
UNCLASSIFIED
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2220-1

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