Feasibility of Estimating 

Pesticide Exposure and 

Dose in Children Using 

Biological Measurements

December 2006

Synthesis Report of Research from EPA’s Science to Achieve Results (STAR) Grant Program: 
P R E PA R E D F O R

U.S. EPA, Office of Research and Development

National Center for Environmental Research

Washington, DC

P R E PA R E D B Y

ICF International

Fairfax, VA

Under EPA Contract No. 68-C-03-137

Work Assignments 00-05, 01-05, and 02-03

EPA/600/S-06/006

U.S. Environmental Protection Agency

Office of Research and Development (8101R)

www.epa.gov

December 2006
	 Disclaimer	 II

	 Executive Summary	 III

1.	 Background	 1

1.1 History and Objectives of STAR Grants Related to Children’s Pesticide Exposures 1

1.2 Research Covered by This Report 1

2.	 Summaries of Supported Research	 3

2.1 Biomarkers of Pesticide Exposure 3

2.2 Children’s Vulnerability to Toxic Substances 6

2.3 Children’s Exposure to Pesticides 8

3.	 Contributions to ORD Research Goals and State of Knowledge	 12

3.1 Contributions to ORD Research Goals 12

3.2 Summary of Major Contributions to the State of Knowledge 14

4. 	 Cited References	 15

5.	 Additional Grant Publications	 17

	 Appendix A. A-1

 Cross-Walk of STAR Grant Contributions to ORD Research Goals and Specific Grant Contributions to These Goals

Contents
ii

Disclaimer

The research described in this document has been funded wholly by the United States Environmental 

Protection Agency (EPA) under the Science to Achieve Results (STAR) grants program. The information does 

not necessarily reflect the views of the Agency and no official endorsement should be inferred. Mention of 

trade names or commercial products does not constitute endorsement or recommendation by EPA for use. 

The information presented in this synthesis report is intended to provide the reader with insights about the 

progress and scientific achievements of STAR research grants. The report lists the grantees whose research is 

discussed, and it also indicates where more detailed peer-reviewed scientific data can be found. This report 

is not sufficiently detailed nor is it intended to be used directly for environmental assessments or decisionmaking. Readers with these interests should instead consult the peer reviewed publications produced by 

the STAR grants and conduct necessary data quality evaluations as required for their assessments. 
iii

Executive Summary

This report provides a brief overview of research funded by 12 grants issued through the Environmental 

Protection Agency’s (EPA) Science to Achieve Results (STAR) program. These grants were all aimed at 

advancing the state of knowledge concerning children’s exposures to pesticides and the potential adverse 

effects of these exposures. Children’s pesticide exposures are a major concern to EPA because of extensive evidence that children may be more vulnerable to the effects of pesticide exposures than adults and 

because children’s exposures to pesticides may be greater than those of adults under typical use scenarios. 

The grants reviewed in this report address three related topics:

• Development of improved biomarkers of children’s pesticide exposure,

• Studies of the basis for children’s vulnerability to pesticides, and 

• Development of improved information relating to the nature and magnitude of children’s 

pesticide exposures.

Biomarkers are physiological or biochemical measurements that can be used to estimate pesticide 

exposures and body burdens, which indicate the amounts of pesticides remaining in the body. Three 

of the grants reviewed in this document investigated the development of less invasive biomarkers 

(analyses of saliva, hair, meconium) that can provide rapid, reliable indications of children’s, infants’, 

and fetal exposures to commonly used pesticides, and have related these biomarkers to indices of early 

neurological development. 

A second group of grants attempted to determine the most important factors explaining why children are 

often disproportionately exposed to pesticides. These studies have confirmed the ubiquity of children’s 

exposure to household pesticide residues, provided insights into the reasons for high variability of exposures in children, and confirmed the importance of specific behaviors (mouthing in infants and toddlers) 

associated with children’s exposures. 

Finally, three of the grants set out to develop detailed estimates of pesticide exposures for specific groups 

of children. These studies evaluated differences in exposures between urban, rural, and agricultural communities, and the effects of ethnicity, socioeconomic factors, and household conditions on the magnitude 

of exposures. One of the grants funded research that compared children’s and adults’ exposures to support 

evaluations of the differences in risks between adults and children exposed to pesticides in similar settings.

Research under these grants has added greatly to the available data on children’s pesticide exposure patterns and potential risks, confirmed the usefulness of biomarkers of pesticide exposure, and identified 

major methodological and data gaps in risk assessment for children exposed to pesticides. 



1. Background

1.1	 History and Objectives of STAR

Grants Related to Children’s

Pesticide Exposures

As part of its mission to improve 

public health and increase the 

reliability with which risks to the 

public health are identified and 

measured, the Office of Research 

and Development (ORD) at the 

Environmental Protection Agency 

(EPA) funds extramural research 

through the Science to Achieve 

Results (STAR) program. The STAR 

program is managed by the ORD’s 

National Center for Environmental Research (NCER) and provides 

grants and fellowships mainly to 

academic researchers to address 

research goals under ORD’s Human 

Health Research Strategy (EPA, 

2003) and the Human Health 

Multi-Year Plan (EPA, 2003). These 

documents, and the research goals, 

are updated regularly. 

A major focus of ORD’s research in 

the last decade has been to improve 

the quality of risk assessments for 

children. In addition, the Agency has 

been supporting the development 

of improved methods for measuring 

and estimating children’s exposure 

to pesticides and other common 

environmental contaminants. Recent 

research has provided extensive 

evidence that children may be more 

vulnerable to the effects of pesticide 

exposures than adults. Children 

may absorb, metabolize, and react 

to pesticides differently than adults 

because of differences in physiology 

associated with specific stages of 

development. In addition, children’s 

behavior patterns differ from 

adults—they spend more time in 

contact with potentially contaminated media such as soil and house 

dust. Thus, they may receive higher 

exposures and doses than adults in 

the same exposure setting. Exposure to pesticides may begin before 

birth, and the effects of prenatal 

exposure are poorly understood. 

Currently available models and data 

are not always adequate to assess 

children’s exposures to pesticides 

or to estimate the risks associated 

with these exposures.

In addition, passage of the Food 

Quality Protection Act (FQPA) of 

1996 requires EPA to specifically and 

quantitatively consider the special 

vulnerability of children in decisions 

related to pesticide tolerance setting. 

This has provided additional incentive for EPA to improve methods for 

characterizing children’s exposure 

to pesticides, how children metabolize pesticides and other chemicals, 

and how the differences between 

children’s and adults’ responses to 

pesticide exposure translate into differences in health risks.

1.2	 Research Covered by This Report

To address these concerns, EPA has 

issued Requests for Applications 

(RFAs) in three major topic areas 

related to children’s pesticide exposures, as summarized in table 1:

• Development of improved biomarkers of children’s pesticide 

exposure,

• Studies of the basis for children’s 

vulnerability to pesticides, and 

• Development of improved information relating to the nature and 

magnitude of children’s pesticide 

exposure.

This report provides a brief overview of 12 grants funded under the 

STAR program in these three general 

areas. The projects listed in table 1 

were initiated between 1996 and 

2001. Progress in research under 

these grants, and important research 

results, are described in section 2 of 

this report. Where projects have not 

been completed, progress through 

2005 is summarized. Section 3 briefly 

discusses how the individual grants 

have contributed to the fulfillment 

of seven specific ORD research goals 

specified in the Human Health 

Research Strategy and the Human 

Health Multi-Year Plan.
Table 1. STAR Grant Research Projects Reviewed in this Synthesis Report

Grant # Project Title

Principal 

Investigator 

(PI)

Project Period

RFA: Biomarkers for the Assessment of Exposure and Toxicity in Children

R828611

Biomarkers and Neurobehavioral Effects of 

Perinatal Exposure to Chlorpyrifos (CPF) and Other 

Organophosphate Insecticides

Wilkins 02/2001–02/2004 

(extended to 02/2006)

R828608

Development of a Physiologically Based Pharmacokinetic/ 

Pharmacodynamic (PBPK-PD) Model to Quantitate 

Biomarkers of Exposure for Organophosphate Insecticides

Timchalk 01/2001–12/2003 

(extended to 05/2005)

R828606 Saliva Biomonitoring for Organophosphorus Pesticide 

Exposures in Children Fenske 09/2000–08/2003 (extended to 08/2005)

R828609

Measurement of Non-Persistent Pesticides in Postpartum 

Meconium as a Biomarker of Prenatal Exposure: 

A Validation Study

Whyatt 07/2000–06/2003 

(extended to 06/2005)

R828610 Chlorotriazine Protein Binding: Biomarkers of Exposure 

and Susceptibility

Tessari

(previously

Andersen)

06/2000–05/2003 

(extended to 05/2006)

RFA: Children’s Vulnerability to Toxic Substances in the Environment

R827440 Ingestion of Pesticides by Children in an Agricultural 

Community on the U.S./Mexico Border Shalat 10/1999–09/2002 (extended to 03/2003)

R827444 Study of Exposure and Body Burden of Children of Different 

Ages to Pesticides in the Environment Raymer 09/1999–08/2002 

R827443

Vulnerability of Young Children to Organophosphate 

Pesticides and Selected Metals through Intermittent 

Exposures in Yuma County, Arizona

 O’Rourke 05/1999–04/2002 

(extended to 09/2004)

RFA: Exposure of Children to Pesticides

R825169 Exposure of Children to Pesticides in Yuma County, Arizona O’Rourke 10/1996–09/1999

R825283 Measuring and Apportioning Children’s Exposure to 

Pesticides in Urban, Suburban, and Rural Communities Sexton 10/1996–09/1999

R825170

Assessing Levels of Organophosphorus Insecticides Which 

Could Expose Children From Pets Treated with Flea Control 

Insecticides

Chambers 10/1996–09/1999

R825171 Total Organophosphorus (OP) Pesticide Exposure Among 

Children in Urban and Rural Environments Fenske 09/1996–09/1999 (extended to 09/2000)


2. Summaries of Supported Research

This section provides brief summaries of the progress and findings of 

the twelve grants listed in table 1. 

Literature publications arising from 

the grants are listed in section 4, 

and detailed progress reports for 

each grant can be found on ORD 

NCER’s Web site 

http://es.epa.gov/ncer/index.html.

2.1	 Biomarkers of Pesticide

Exposure

EPA released an RFA entitled “Biomarkers for the Assessment of Exposure 

and Toxicity in Children” in 2000. In 

2000 and 2001, ORD awarded five 

grants to researchers investigating various aspects of biomarkers 

research. The RFA solicited research 

that would establish normative data 

for biomarkers, evaluate biomarker 

sensitivity in predicting exposure 

or health outcomes, and lead to 

the development of less invasive 

biomarkers.

Biomarkers and Neurobehavioral Effects of 

Perinatal Exposure to Chlorpyrifos (CPF) and 

Other Organophosphate (OP) Insecticides 

This grant funded a large prospective longitudinal study of the 

relationships between biomarkers 

of exposure to common household 

pesticides (chlorpyrifos, diazinon, 

other OP pesticides, and synthetic 

pyrethroids) and indices of infant 

neurological development from birth 

through 2 years of age. 

In spring 2005, mothers and children were still being recruited to 

reach a target sample of 176 low-risk 

pregnancies. The study involves 

an analysis of maternal urine and 

blood samples (at study entry and 

postpartum), infant urine samples 

(at or before 3 months, then every 

7 months to 24 months), and infant 

blood samples (12 and 24 months) 

for pesticide biomarkers. Infant 

neurological development is being 

measured at 3, 12, and 24 months 

using the Bayley Scales of Infant 

Development 2nd Edition (BSID-II) 

and Child Development Index (CDI) 

tests. Urine and blood samples were 

originally to be analyzed for major 

metabolites of CPF and other OP 

pesticides, but the ban on household 

uses of CPF has caused a shift to 

synthetic pyrethroids. Therefore, the 

biological samples are also being analyzed for pyrethroid metabolites. In 

addition to biomonitoring, data are 

being gathered related to maternal 

exposure to cigarette smoke, ethnicity, socioeconomic status, parental 

intelligence, family structure, as well 

as clinical birth data.

According to the PI’s June 2005 

progress report, 117 subjects were 

actively enrolled; 104 of these 

women have provided second 

urine specimens and completed 

questionnaires. The investigators 

collected 83 diaper urine samples 

from 2-month-old infants, 70 

samples from 9-month-old infants, 

46 samples from 16-month-old 

infants, and 29 samples from 23-

month-old infants. The researchers 

also performed neurological testing 

(BSID-II) of 80 3-month-old infants 

and 21 24-month-old infants. 

The researchers have analyzed 

and reviewed 198 maternal urine 

samples. In addition, approximately 

one-third of the 228 analyzed infant 

diaper urine samples have been 

reviewed. Organophosphates, 

pyrethroids, and cotinine (cigarette 

smoke) were detected in several of the 

198 maternal urine samples analyzed. 

Final results are not yet available. 

Development of a Physiologically Based 

Pharmacokinetic/Pharmacodynamic (PBPKPD) Model to Quantitate Biomarkers of 

Exposure for Organophosphate Insecticides

The purpose of this research was 

to develop and validate an agedependent PBPK-PD model for the 

OP pesticide CPF. The model was 

intended to include age-dependent 

changes in metabolism and pharmacodynamic response to facilitate 

quantitative biomonitoring of OP 

pesticides.

Research under this grant built on 

previous work by these authors on 

PBPK-PD modeling of OP pesticide 

responses in animals and humans. 

Researchers developed analytical 

PI:

Dr. John Wilkins, 

Ohio State University

EPA grant number: 

R828611

Amount: 

$1,126,423

Duration:

February 2001 through February 2006


methods for quantifying CPF metabolites, investigated in vivo and in vitro 

mechanisms of CPF metabolism, and 

refined the PBPK-PD model to support the evaluation of noninvasive 

biomarkers of exposure.

In the first year, grantees used their 

previously developed human PBPKPD model to evaluate the effect of 

the known polymorphism of CPF 

oxonase (PON-1, a major detoxifying enzyme) on brain and plasma 

metabolite levels and plasma esterase 

inhibition (Timchalk et al., 2002). 

They found that estimated brain

concentrations of CPF-oxon were

nearly equal for all three phenotypes (QQ, QR, and RR) at low

single doses (~ 5 μg/kg). At higher

doses (0.5–5.0 mg/kg) the brain

oxon concentrations were significantly higher in the medium- (QR)

and low-activity (QQ) phenotypes.

They concluded that at low doses

other detoxifying enzymes will

likely prevent significant toxicity

(as indicated by butylcholinesterase [BuChE] inhibition), but

at higher doses, PON-1 polymorphism may contribute significantly to variations in human

sensitivity to CPF exposure.

Grantees also investigated the use of 

saliva cholinesterase levels as a possible biomarker for CPF exposures 

(Kousba et al., 2003). Experiments 

in rats showed that salivary esterase activity is predominantly (>95 

percent) BuChE. Kinetic parameters 

for salivary esterase inhibition (active 

site concentration, Ki for CPF-oxon, 

and spontaneous reactivation rate) 

derived from the experiments were 

incorporated into the PBPK-PD 

model. The revised model was able 

to reproduce the time course of 

salivary BuChE inhibition in rats, 

supporting the potential use of saliva 

sampling as a noninvasive biomarker 

for acute CPF exposures (Timchalk et 

al., 2004).

Experiments were conducted to 

evaluate the role of intestinal metabolism in modifying the absorbed dose 

of CPF after ingestion exposure 

(Poet et al., 2003). Production of 

major CPF metabolites (CPF-oxon 

and trichlorpyridinol [TCPy]) by 

microsome preparations from rat 

hepatocytes and intestinal enterocytes was tracked using analytical 

methods developed for this study. 

Kinetic parameters (Km, Vmax) were 

measured for the major metabolic 

reactions (desulfurization and dearylization by cytochromes, hydrolysis 

by PON-1), and the overall metabolic 

capacities of the liver and intestine were compared. The authors 

concluded that first-pass metabolism 

(primarily detoxification) in the intestine may affect the systemic bioavailability and toxicity of CPF, especially 

at low doses.

The project results showed that 

the age-dependent rat model is 

quantitatively consistent with the 

general understanding of OP toxicity 

in younger versus older animals. 

The model suggested that neonatal 

rats are more sensitive to the highdose acute effects of OP exposure; 

however, at low, environmentally relevant exposure levels, the neonatal 

rat model was not substantially more 

sensitive than adult rats.

Saliva Biomonitoring for Organophosphorus 

Pesticide Exposures in Children 

The purpose of this study was to 

evaluate the feasibility of quantifying children’s exposure to the OP 

pesticides diazinon and CPF, as 

well as a third pesticide from the 

synthetic pyrethroid family, permethrin, through saliva biomonitoring 

of pesticide levels.

Research performed under this 

grant included (1) measurement of 

diazinon concentrations in saliva 

after intravenous injection in rats, 

(2) evaluation of the effects of varying diazinon doses and salivary flow 

rate on diazinon excretion in saliva, 

(3) determination of the correlation 

between salivary and plasma concentrations, (4) measurements of CPF 

and diazinon concentrations in the 

saliva and urine of children in agricultural communities, and (5) development of a pharmacokinetic model for 

CPF and diazinon using salivary and 

urinary markers.

In the first part of the study, anesthetized rats were injected with various 

doses of diazinon. Time-course 

samples of plasma and saliva were 

obtained through 250 minutes after 

dosing. Concentrations of diazinon 

were determined using an enzymelinked immunosorbent assay (ELISA). 

Statistical analyses of the data 

revealed that diazinon concentrations were consistently lower in saliva 

samples than in plasma samples, 

regardless of dose level, sampling 

time, or salivary flow rate. The finding suggests that salivary excretion

of diazinon is diffusion-limited,

rather than transporter-mediated.

PI: 

Dr. Richard Fenske,

University of Washington

EPA Grant Number: 

R828606

Amount:

$742,597

Duration: 

September 2000 through August 2005

PI:

Dr. Charles Timchalk, Battelle, 

Pacific Northwest Division

EPA Grant Number: 

R828608

Amount: 

$733,174 

Duration: 

January 2001 through May 2005


A strong correlation was found

between pesticide metabolite

concentrations in saliva and

plasma (Lu et al., 2003). Additional analysis revealed that the

concentration of diazinon in saliva

reflected the fraction of diazinon that did not bind to plasma

proteins. This information allowed

accurate prediction of the relative concentrations of diazinon in

plasma and saliva, supporting the

use of saliva biomonitoring as a

noninvasive substitute for plasma

sampling in the measurement of

human diazinon exposures.

Data from animals dosed with CPF 

suggest that CPF is metabolized within 

minutes in blood, and therefore, it is 

not measurable in saliva.

Permethrin was selected as one of 

the chemicals to be measured in 

saliva using the ELISA assay; however, 

the ELISA assay for permethrin was 

not optimized for use in specimen 

samples. Additional research is being 

conducted to improve the permethrin ELISA assay.

The second part of the study, conducted in Nicaragua, assessed pesticide exposures for 7 corn farmers 

who used CPF, 10 banana plantation 

workers who applied diazinon, and 

their children. The investigators 

conducted urine, blood, and saliva 

sampling. Their analysis of the urine 

samples indicated exposure to CPF 

for the farmers, plantation workers, and children, but the saliva 

samples did not indicate exposure. 

This results from the rapid metabolism and clearance of CPF. This 

finding was consistent with the 

animal studies. The study identified 

two important exposure factors: 

proximity to spraying and spray 

mixture preparation in the home. 

The analysis detected exposure to 

diazinon among the applicators, but 

not among their children. Diazinon

concentrations in the workers’

saliva were significantly correlated

with the time-matched samples of

their blood. Diazinon concentrations in saliva also corresponded

with excretion of the primary

urinary metabolite of diazinon in

these applicators.

The investigators suggested that

saliva sampling is a promising

monitoring method because it

is noninvasive, and it measures

pesticides rather than pesticide

metabolites. The method may not

be suitable for some compounds

(e.g., CPF), and dehydration

among the study subjects can

adversely affect sample collection.

Measurement of Non-Persistent Pesticides 

in Postpartum Meconium as a Biomarker of 

Prenatal Exposure: A Validation Study 

The purpose of this research was to 

validate a new noninvasive biomarker 

of prenatal exposure to OPs and other 

pesticides. The study design involved 

measuring the levels of a large number of pesticide residues in meconium 

samples from 100 infants born to African American or Dominican women 

from Manhattan and the Bronx, New 

York. Pesticide levels in meconium 

were compared with the results of 

continuous indoor and personal air 

monitoring during the final 2 months 

of pregnancy and with self-reported 

pesticide use (Whyatt et al., 2003).

The study included 102 mothernewborn pairs. Biologic samples were 

collected from the mother during 

pregnancy and from the mother and 

newborn at delivery and included: 

253 repeat spot urine samples collected from the mothers during pregnancy; urine samples collected from 

the mothers (n=74) and newborns 

(n=69) after delivery; maternal blood 

(n=95) and umbilical cord blood 

(n=69) collected after delivery; and 

postpartum meconium (n=85).

Eleven insecticide metabolites were 

measured in meconium. Those 

detected most frequently were 

carbofuranphenol, 1-naphthol, 4-

nitrophenol, 2-isopropoxyphenol, 

and TCPy. TCPy levels in meconium 

were correlated positively but not 

significantly with CPF in the indoor 

air samples and were correlated 

positively and significantly with TCPy 

levels in the prenatal maternal urine 

samples, both before and after adjusting for creatinine. TCPy in meconium 

also was correlated significantly with 

CPF levels in both the maternal blood 

and umbilical cord blood samples 

collected after delivery. 

CPF, diazinon, and propoxur were 

frequently detected in continuous air 

sampling results from 102 women 

between the week 32 of pregnancy 

and delivery (at 40–42 weeks). Levels 

of the individual pesticides were 

generally highly correlated (relatively 

constant) over time for individual 

women but varied greatly among individuals, with a few women showing 

much higher exposures.

The results from this study

indicate that meconium is a

useful biomarker of fetal prenatal exposure to CPF. CPF, or its

metabolite, TCPy, was the only

compound that was consistently

detected across all environment

and biologic matrices in the current study. While only a weak

correlation between CPF levels

in indoor air samples and TCPy

levels in meconium was observed,

there was a consistent and highly

observed correlation between

TCPy levels in other biologic

matrices and meconium. Thus,

TCPy appears to provide a valuPI: 

Dr. Robin Whyatt,

Columbia University,

Mailman School of Public Health

EPA Grant Number: 

R828609

Amount: 

$744,866

Duration: 

July 2000 through June 2005
able internal dosimeter for CPF

exposures during pregnancy.

Chlorotriazine Protein Binding: 

Biomarkers of Exposure and Susceptibility

The purpose of this research was to 

develop analytical methods to characterize the reactivity of chlorotriazines with hemoglobin protein, and 

evaluate whether binding to hair 

proteins can be used as a noninvasive biomarker of triazine exposure. The investigators proposed to 

develop an age-specific PBPK model 

to assess tissue concentrations of 

chlorotriazines and their metabolites 

over time and validate the model 

using animal and human data.

Atrazine (ATRA) is a high-volume 

pesticide that has been found in a 

number of drinking water supplies. 

Available biomarkers of exposure 

have been limited primarily to 

metabolites in urine, and the details 

of ATRA absorption, metabolism, 

and excretion were not well characterized before this work. A major 

achievement under this grant was 

the development of an analytical 

method capable of detecting low 

levels of ATRA and its metabolites 

in serum (Brzezicki et al., 2003). 

Previous efforts to study the pharmacokinetics of ATRA had been limited 

by the lack of a metabolite-specific 

method, and were primarily based 

on radiotracer data. The analytical 

method included cleanup, liquidliquid extraction, and derivatization 

with methyl bromide/tetrabutylammonium chloride. The method 

demonstrated clean separation of 

ATRA and its major metabolites with 

a level of quantitation (LOQ) of 100 

ng/ml for all species. It was validated 

using spiked serum samples as well 

as an in vivo metabolite analysis 

after single-dose administration to 

Sprague-Dawley rats.

The investigators also developed 

a detailed PBPK model for ATRA 

(McMullin et al., 2003) in adult rats. 

The model simulated the metabolism, transformation, and elimination 

of two major classes of metabolites, 

the chlorinated triazines and glutathione conjugates. Modeled processes 

included gastrointestinal absorption, 

metabolism by cytochrome P450 

isozymes, conjugation by glutathione 

(GSH), and the binding of chlorotriazines to hemoglobin and serum 

proteins. Development of the model 

involved extensive research on chlorotriazine-globin binding rates and 

mechanisms. The PBPK model was 

validated against previous multipledose radiotracer studies of total ATRA 

metabolites and against data from a 

single-dose time course study in rats. 

The latter study used the previously 

developed analytical method to 

quantify ATRA and its metabolites in 

serum over time. The model was able 

to accurately fit both the single- and 

multiple-dose data. The importance

of chlorotriazine reactions with

serum proteins was confirmed

and the rate constants for hemoglobin and serum binding and

elimination were estimated. The

slow gastrointestinal absorption of

ATRA, followed by rapid metabolism to 2-chloro-4,6-diamino-1,3,5-

s-triazine (DACT) were confirmed

as dominant features of ATRA

pharmacokinetics.

According to the PI’s June 2005 

progress report, the research team 

was investigating methods for pretreatment, digestion, and extraction 

of hair and the formation of other 

protein-atrazine adducts.

2.2	 Children’s Vulnerability to

Toxic Substances

In 1999, EPA released the RFA 

“Children’s Vulnerability to Toxic 

Substances in the Environment.” 

This request focused on research 

that quantified children’s exposure 

to chemicals by examining factors 

contributing to exposure, such as 

frequency, duration, activity patterns, 

temporal variation, and individual 

physiological differences. Development of predictive exposure models 

incorporating these factors were also 

encouraged and funded. 

Ingestion of Pesticides by Children in 

an Agricultural Community on the U.S./

Mexico Border 

The purpose of this research was to 

evaluate children’s exposure to OP 

pesticides in households within rural, 

agricultural communities along the 

U.S./Mexico border. The research 

attempts to determine the influence 

of hygiene practices and behavior 

patterns of children on pesticide 

dose level. 

Research under this grant included 

(1) collection of environmental and 

urine samples and analysis for the 

presence of pesticides and pesticide 

residues, (2) statistical analyses to 

evaluate the associations between 

pesticide levels in environmental 

samples and pesticide body burdens, 

and (3) observation and analyses of 

children’s mouthing behaviors. 

PI: 

Dr. Stuart Shalat, University 

of Medicine and Dentistry 

of New Jersey 

EPA Grant Number: 

R827440

Amount: 

$710,231 

Duration: 

October 1999 through March 2003

PI: 

Dr. John Tessari 

(previously Dr. Melvin Andersen), 

Colorado State University

EPA Grant Number: 

R828610

Amount: 

$710,617

Duration: 

June 2000 through May 2006


Environmental sampling revealed 

detectable levels of pesticides in 

house dust in 75 percent of the 29 

homes studied; however, no correlation was found between levels of 

pesticides in house dust and pesticide metabolite levels in urine. Half 

of the hand-wipe samples taken from 

the children in the study contained 

levels of pesticides above the detection limit. There was a significant

association between pesticide levels on children’s hands and pesticide metabolite levels in urine.

Researchers conjectured this

relationship was associated with

frequent hand-to-mouth behaviors. Video recordings of the participants’ behavior will be analyzed to 

help substantiate this hypothesis. 

Dimethyl phosphate (DMP) and 

diethyl thiophosphate (DETP) were 

the most commonly detected metabolites that were found in 100 percent 

and 96 percent of the subjects, 

respectively. The pesticides methyl 

parathion and azinophos-methyl 

were detected in both hand and dust 

samples taken, consistent with the 

detection of its metabolite, DMP, in 

urine samples. 

No association was found between

hand surface area and the total

amount of pesticides on children’s

hands. This result suggests that

hand surface area may not be

useful as a scaling factor in risk

assessments. Age was inversely

and significantly correlated with

estimated dose levels, while gender was not found to be predictive

of body burden.

All of the urine samples contained 

concentrations of at least one 

pesticide metabolite above the limit 

of detection. Ninety-five of those 

samples contained more than one 

metabolite above the detection limit 

(Shalat et al., 2003).

Study of Exposure and Body Burden of 

Children of Different Ages to Pesticides in 

the Environment

Grantees set out to evaluate whether 

children incur more frequent and 

higher exposures to pesticides than 

adults living in the same household. Secondary objectives included 

evaluating pediatric environmental 

exposure rates and dose distributions 

in relation to demographic variables.

Research under this grant builds on 

previous work of these authors on 

the National Human Exposure Assessment Study (NHEXAS) by using the 

same study population to examine 

exposures to CPF, diazinon, ATRA, 

and malathion (MDA). The research 

involved (1) developing a means of 

collecting infant urine samples, (2) 

collecting and analyzing environmental and urine samples, and (3) 

correlating observed behavioral and 

demographic data with measured 

exposures.

After encountering difficulties finding 

detectable levels of pesticide residues 

of target analytes to study in Rice 

and Goodhue Counties, Minnesota, 

grantees moved the study to Moore 

County in western Minnesota. 

Pesticide and pesticide metabolites 

were measured in indoor air, exhaled 

breath, domestic water, surface 

wipes, house dust, dermal rinses, and 

body suits. 

Many pesticides and pesticide 

metabolites were found in the first 

morning urine samples from both 

children and adults. Estimates of 

mean exposures were dominated 

by a few highly exposed individuals. 

Statistical analyses revealed significant differences between the

metabolite levels present in the

urine of children and adults. Specifically, the grantees determined

that levels of the CPF metabolite

TCPy in children’s hydrolyzed

urine samples were on average

two times the levels detected in

adults. Similarly, levels of ATRA

and the diazinon metabolite 2-

isopropyl-6-methyl-4-pyrimidinol

(IMP) detected in nonhydrolyzed

urine samples averaged to be two

and seven times greater, respectively, in children than in adults.

No other significant differences

between adults’ and children’s

pollutant exposure or body burdens were identified.

There were significant differences

in the levels of contaminants

found in children’s urine samples

from differing age groups. Nonhydrolyzed urine sample analysis

revealed that children birth to 3

years old excreted 16 times more

of the diazinon metabolite IMP

(mean=245 ng/ml) than children

ages 4 to 12 (mean=14 ng/ml).

Similarly, urine of the younger

pediatric cohort contained more

than twice as much CPF-oxon

(mean=0.46 ng/ml), a major CPF

metabolite, than that of the 4- to

12-year-old group (mean=0.17 ng/

ml) on the third day of the study.

Conversely, the urine of children 4 to 12 years old contained

significantly higher concentrations

of TCPy and ATRA than that of

children birth to 3 years old. Concentrations of ATRA in the nonhydrolyzed urine of children 4 to 12

(mean=0.076 ng/ml) were significantly higher than levels found in

the younger group (mean=0.004

ng/ml) on the second day of

the study. The following day,

seven times the level of TCPy

was found in the nonhydrolyzed

PI: 

Dr. James Raymer, 

Research Triangle Institute

EPA Grant Number:

R827444

Amount:

$819,063 

Duration:

September 1999 through August 2002


urine of children 4 to 12 years

old (mean=0.54 ng/ml) than the

urine of the younger children

(mean=0.078 ng/ml).

Vulnerability of Young Children to 

Organophosphate Pesticides and Selected 

Metals through Intermittent Exposures in 

Yuma County, Arizona

The two major objectives of this 

effort were to evaluate the routes 

and amounts of OP pesticide and 

metal exposure among young 

children and identify activities that 

result in increased children’s exposure to contaminants in the home.

Activities under this grant included 

(1) collection and analysis of samples 

of exposure media, (2) collection and 

analysis of pediatric urine samples, 

(3) collection and analysis of dermal 

hand-wipe samples, (4) administration of questionnaires about general 

household conditions and parental 

occupation, and (5) analyses of 

recorded activities and play areas 

of children to identify pesticide 

exposure pathways. Environmental 

samples were analyzed for nine OP 

pesticides (including CPF, diazinon, 

and MDA) and heavy metals; urine 

samples were also analyzed for OP 

metabolites. 

The results of household dust and 

pediatric urine samples of children 

living in agricultural communities 

were used as screening tools to 

identify potential participants with 

elevated pesticide exposure or risk of 

exposure. The recruited population 

of 217 was narrowed to 45 children 

who were then divided into low and 

high exposure groups matched by 

age and gender. The levels of metals 

in urine samples were generally low 

and showed no evidence of exposures above expected background 

levels. The investigators therefore 

abandoned their planned analyses of 

heavy metal exposures.

Preliminary results revealed a

number of important behavior

patterns that were associated with

pesticide exposures. Children

with the highest exposure levels

were males who spent the greatest

amount of time playing outdoors.

Similarly, children who played

extensively in laundry rooms and

entry ways exhibited higher rates

of pesticide metabolites in urine

than those who did not play, or

played less, in these areas.

Video analyses completed to date 

indicate that the number of hand-tomouth, hand-to-food, and mouthing 

activities in a given time period are 

more accurate predictors of exposure than the time a child spends 

touching a contaminated item or 

surface. Repeated wipes from hands 

of the same child over a short time 

frame (hours) reflected the same 

concentration and loading value 

repeatedly. This suggests that

frequent hand washing does little

to reduce children’s exposures in

the household if chemical contamination is readily accessible.

Additional preliminary analyses appear to have identified a

method for predicting exposure

to contaminants using a urinary

assay quantifying the presence of

an endogenous metabolite.

2.3 Children’s Exposure

to Pesticides

EPA awarded four grants as a result 

of the RFA entitled “The Exposure 

of Children to Pesticides” that was 

released in 1996. This RFA requested 

research proposals that would 

enhance development of pediatric pesticide exposure assessment 

methods by characterizing the effect 

of age and behavioral factors on pesticide exposure. Additional research 

priorities set by this RFA included 

development of methods for assessing cumulative exposures from one 

or multiple pathways. 

Exposure of Children to Pesticides 

in Yuma County, Arizona 

The purpose of this study was to 

compare the OP pesticide exposure 

and exposure pathways in children 

living in agricultural communities 

to those living in nonagricultural 

communities in Arizona. Creatinine 

levels were used to normalize urinary 

biomarker data of the dialkylphosphates, which are common OP 

pesticide metabolites. Major study 

findings were reported in O’Rourke 

et al. (2000).

Communities in Arizona within 15 

miles of the U.S./Mexico Border (46 

percent from San Luis, 49 percent 

from Somerton, and 5 percent from 

Gadsden/Yuma) were selected from 

the NHEXAS, 1990 census tract, and 

the Arizona Border Survey (ABS), to 

create the Children’s Exposure to 

Pesticide Survey (CPS) for this study. 

All children were Latino, most households were bilingual, 51 percent were 

male, and 49 percent were female. 

Spanish was the preferred language 

in 97 percent of the homes surveyed. 

Study subjects were recruited in two 

ways, a population-based probability 

design and from families enrolled 

PI: 

Mary Kay O’Rourke 

University of Arizona

EPA Grant Number: 

R825169

Amount: 

$596,039

Duration: 

PI: October 1996 through September 1999

Dr. Mary Kay O’Rourke, 

University of Arizona

EPA Grant Number:

R827443

Amount: 

$712,313

Duration: 

May 1999 through September 2004


in services catering to children, with 

children that displayed bladder 

control (2 to 6 years old). A total of 

154 children participated in the study 

(O’Rourke et al., 2000). Descriptive 

questions were submitted to each 

household and a two-visit screening 

was used to develop a 1-day record of 

typical activities and duration and a 

1-day record of all food and beverages consumed. A first morning 

void urine sample and dust sample 

were taken during the screening stage 

as well. Urinary OP, OP metabolites, 

and creatinine were analyzed. 

A total of 154 urine samples were 

collected with a mean urinary creatinine concentration of 0.90 g/L. The 

urinary creatinine data appeared to 

be lower than expected for the first 

bladder voiding. After questioning the 

families about their children’s urinary 

behavior, 16 percent of the children 

were known to wet the bed and ~50 

percent may have used the toilet in 

the night. Differences in seasonal 

creatinine excretions were observed 

when comparing autumn and spring 

(Mann-Whitney, P=0.038) and summer and autumn values (Mann-Whitney, P=0.041). Additional comparisons of the data to the larger data set 

from the 1996 National Health and 

Nutrition Examination (NHANES) III 

(DHHS, 1996) survey indicated racial 

differences, with African-American 

children having statistically higher 

creatinine values (mean=0.94 g/L; 

n=173; P=0.0000) as compared to 

Caucasian children (mean=0.78 g/L; 

n=285). Ethnic differences were 

observed with non-Hispanic children displaying a significant increase 

in creatinine (0.86 g/L; n=287; 

P=0.005) as compared to Hispanic 

children (mean=0.77 g/L; n=190). 

Metabolites of OP pesticides, dialkylphosphates, were measured in the 

urine of 121 children who were 6 

years or younger with valid creatine 

analyses. Thirty-three percent of 

the subjects had detectable levels of 

at least one metabolite, and many 

contained multiple metabolites. The 

dialkylphosphate distribution was 

as follows: 5 percent of the samples contained diethylphosphates 

(DEPs), 25 percent dimethylphosphates (DMPs), 26 percent dimethylphosphorothioates (DMTPs), and 

3 percent dimethylphosphordithioates (DMDTP). Theoretical absorbed 

daily doses (ADDs) were calculated 

for three children that excreted 

the highest amount of biomarker, 

assuming that a single pesticide 

was metabolized and that all of the 

metabolite had cleared. CPF and 

diazinon are both used in the Yuma 

area and could be responsible for 

the DEP metabolites. At the highest 

DEP excretion, the ADD for diazinon was 126 times the permissible 

reference dose. DMP and DMTP are 

associated with methyl parathion 

metabolism, and the theoretical 

ADDs were 385 and 61 times the 

reference dose, respectively. When

examining aggregate exposure to

OPs, floor dust appears to be the

major medium through which

young children are exposed (68.8

percent), followed by solid food

(18.8 percent) and beverage (10.4

percent). Air and water (modeled

from ABS and NHEXAS data) contribute less than 2 percent to the

total aggregate exposure.

Measuring and Apportioning Children’s 

Exposure to Pesticides in Urban, Suburban, 

and Rural Communities

The purpose of this research grant 

was to determine children’s actual 

exposure to pesticides, and to assess 

if current regulatory decisions 

(e.g., the Food Quality Protection 

Act of 1996) are either protective of 

children’s health or cost effective. 

The study focused on collecting 

NHEXAS data for exposure to 4 

primary pesticides (CPF, diazinon, 

MDA, and ATRA), 14 secondary pesticides, and 13 polyaromatic hydrocarbons (PAHs). The study was a part 

of NHEXAS.

Children (102 children/families, 3 to 

12 years old) were recruited from 

the urban Minneapolis/St. Paul area 

and rural Goodhue and Rice Counties. Analytical samples taken were as 

follows: 6-day integrated personalindoor air; 4-day integrated food and 

beverages samples (duplicate diet); 

hand rinses; first morning urine 

voids; indoor and outdoor air; drinking water; surface wipes; and soils 

(Quackenboss et al., 2000). Questionnaire data were also collected, 

diary data of the child’s activities 

were maintained, and a subset of 

children were videotaped to quantify 

children’s hand-to-mouth activities.

Pesticide products were found in 

97 percent of the homes with an 88 

percent self-reported use (Adgate et 

al., 2000). The population-weighted 

mean numbers of products used and 

stored in a household in the prior 

year were 3.1 and 6.0, respectively. 

These results were at least twice the 

national averages reported in two 

previous major studies. However, no 

differences were observed between 

urban and rural communities, 

socioeconomic and/or racial/ethnic 

factors. CPF and its metabolites 

were the most commonly measured 

compounds found in the samples 

analyzed from personal air (95.0 

percent), indoor air (91.5 percent), 

and dust samples (61.6 percent). 

Levels of MDA were detected in 

54.1, 67.0, and 0.0 percent of these 

samples, respectively. Diazinon 

was detected in 64.1, 68.0, and 7.1 

percent of personal air, indoor air, 

and house dust samples, respectively. 

ATRA, CPF, and diazinon were all 

detected in fewer than 16 percent 

PI: 

Dr. Ken Sexton, 

University of Minnesota

EPA Grant Number: 

R825283

Amount: 

$745,572 

Duration: 

October 1996 through September 1999
10

of outdoor air and soil samples. CPF 

was detected in 57 percent of food 

samples; detection frequencies for 

MDA, ATRA, and diazinon were 46, 8, 

and 3 percent, respectively (Sexton et 

al., 2003).

Hand-to-mouth behavior was the 

most observed exposure pathway in 

children. The 3- to 4-year-old children displayed the most frequent 

hand-to-mouth actions, however, 

the activity was also seen in older 

children at a lower frequency. There 

were few handwashings preceding 

food handling and consumption for 

all age groups with females washing 

their hands more frequently than 

males (Adgate et al., 2001 and 

Freeman et al., 2001). 

ATRA, CPF, and MDA were detected 

in greater than 30 percent of the 

households in dust and hand washing 

samples. The median range of CPF 

and/or metabolites found in the dust 

samples were 0.07–0.42 ng/cm2 (Lioy 

et al., 2000). CPF and/or metabolites 

were found in over 50 percent of the 

hand samples with a median amount 

of 0.03 ng/hand and a maximum of 

2.14 ng/hand.

Urinary metabolites were analyzed 

from at least three first morning 

voids over a five day period in 90 

children that were in households that 

reported frequent use of pesticides. 

Urinary pesticide metabolites (not 

adjusted for creatinine) percent 

detected were 96.6 percent CPF 

(6.9 μg/g or 59.0 μg/g, median and 

maximum, respectively), 46.6 percent 

MDA, and 4.4 percent ATRA; diazinon was not analyzed. Interchild 

variability (carbamates and related 

compounds [1-NAP], CPF and related 

compounds [TCPy], and MDA) 

indicated a larger sample size was 

needed to better assess exposure for 

the general population. Intrachild

average variability ranges were

1.3 times the weighted population mean for 1-NAP, 1.5 times the

weighted population mean for

MDA, and approximately equal

the weighted population mean for

TCPy suggesting single measurements are insufficient to characterize the relative magnitude of

long-term exposure to the parent

compound (Clayton et al., 2003).

Assessing Levels of Organophosphorus 

Insecticides Which Could Expose Children 

From Pets Treated with Flea Control 

Insecticides

The objective of this project was 

to measure potential pesticide 

exposures to dog owners and their 

children from flea-dipped or collartreated dogs. Major findings can be 

found in Boone et al. (2001).

The researchers recruited dogs from 

the general population. These dogs 

were treated with commercial, nonprescription flea control dips (CPF 

or phosmet) or collars (tetrachlorvinphos or CPF) and were rubbed on 

the midline back area for five minutes 

with a cotton glove. The glove was 

extracted and analyzed for pesticide 

residues. Pesticide residue samples 

were taken at 4 hours, and then at 

7, 14, and 21 days after application. 

Collared animals were sampled from 

the neck area with and without the 

collar. The CPF-dipped animals were 

split into two groups (12 dogs/group) 

to assess if the pesticide accumulated 

over time; one group of dogs was 

shampooed before each reapplication; a second group was not bathed. 

Plasma butyrylcholinesterase and 

acetylcholinesterase activity were 

assayed in the dogs, and their owners’ urine was analyzed for pesticide 

metabolites.

The transferable OP pesticide 

residues from the CPF and phosmetdipped dogs were found to peak 

shortly after flea dip administration. CPF residues decreased by 87 

percent after 1 week, 92 percent by 

week 2, and 97 percent by week 3, 

with similar residue attenuation in 

the phosmet-dipped dogs. There was 

no evidence of CPF accumulation 

from one dipping to the next in the 

nonshampooed dogs. Considerable 

individual variablity was observed; 

however, fur length was not considered a factor in the variability. Plasma 

butyrylcholinesterase activity in the 

nonshampooed CPF treated dogs was 

inhibited 50–75 percent throughout 

the study and acetylcholinesterase 

was inhibited by 11–18 percent, 

with no appreciable cholinesterase 

inhibition observed with the phosmet 

dipped or shampooed group of CPFdipped dogs. 

The tetrachlorvinphos and CPF collars both yielded the least transferable residues from the backs of the 

dogs. The highest residues were 

found in the neck area when the 

tetrachlorvinphos collar was in place. 

The data suggest the pesticide does 

not migrate from the neck down 

the back. An appreciable degree of 

individual variation in the residues 

detected was observed with no 

correlation to fur length. There was 

negligible inhibition of the plasma 

cholinesterase in dogs with tetrachlorvinphos collars. In contrast, 

the CPF collar pesticide residues 

were considerably lower than those 

obtained with tetrachlorvinphos 

collars; however, the plasma cholinesterase activities in the dogs were 

inhibited about 60 percent compared 

to pretest activities throughout the 

sampling period.

Urine samples from the adults

and children (aged 3 to 12 years)

in the households with dogs that

used collars indicated that TCPy

levels increased when the collars were placed on the dogs.

The magnitude of the increase in

TCPy levels was highly variable

PI: 

Dr. Janice Chambers, 

Mississippi State University

EPA Grant Number: 

R825170

Amount: 

$597,804 

Duration: 

October 1996 through September 1999
11

among both adults and children,

and adjusting the TCPy levels for

urinary creatinine concentrations 

did not significantly reduce the

variability. Because of the high

variability, the difference between

precollar and postcollar TCPy levels in urine, while large for some

individuals, was not statistically

significant for the study group

taken as a whole.

Total Organophosphorus Pesticide 

Exposure Among Children in Urban and 

Rural Environments

The primary objectives of the research 

conducted under this grant were to 

characterize the geographic, temporal, 

age-related, and gender-related variability in total OP pesticide exposure 

in children living in certain areas of 

Washington State and to determine 

the relative contributions of environmental sources to the children’s total 

OP pesticide body burdens. 

Two biologic monitoring experiments 

were conducted to measure pesticide 

metabolites in 2- to 5-year-old children’s urine. Samples were analyzed 

for OP pesticide metabolites and six 

dialkylphosphates (DAP). The first 

study evaluated 110 children with 

sampling in the spring and fall, and 

the other involved 44 children from 

agricultural areas of Washington State 

whose urine was sampled monthly 

over 21 months. In addition to the 

first two efforts, the third field study 

was conducted to evaluate biomarkers in 13 children with higher potential OP pesticide exposure as judged 

based on behavioral surveys and residential location. Samples of inhaled 

air (24-hour), soil, house dust, drinking water, 24-hour duplicate diet, 

and 24-hour urine were analyzed. 

Another study measured DAP levels 

in urine from preschool children of 

urban and suburban communities 

that consumed a conventional diet or 

an organic diet.

In the first field study, no differences 

in DAP levels were observed when 

comparing values from spring and 

fall, urban or suburban communities, gender, age, family income, 

or housing type. Children whose 

parents reported pesticide use in 

the garden had significantly higher 

levels of dimethyl and diethyl DAPs 

in their urine (Lu et al., 2001). In the 

second field effort, a strong temporal 

trend in OP pesticide exposure was 

observed with DAP concentrations 

displaying an elevation in months 

when OP pesticides were sprayed. 

Boys had significantly higher DAP 

metabolite levels in their urine than 

did girls. No differences were found 

based on child age, parental occupation, or residential proximity to fields 

(Koch et al., 2002). The data were 

analyzed by a mixed-effects analysis 

of variance (ANOVA) model that 

compared the within- and betweenchild variance and standard deviation in urinary DMTP concentration 

during both the spray and nonspray 

months. The results of this analysis 

demonstrated that, regardless of time 

of year, the within-child component 

of variability is much greater than 

the between-child component for 

this population. These results show

that urinary DMTP concentration varied more from day-to-day

than from child-to-child in this

population. In the third field effort, 

azinphosmethyl, CPF, malathion, 

methidathion, methyl parathion, and 

phosmet were detected in the food 

of these children. Azinphosmethyl 

(10 percent) was the compound 

found most frequently, particularly in 

foods or beverages containing apples 

or apple juice. No detections were 

found to be above legal tolerances for 

residues on produce. However, the 

acute population-adjusted reference 

dose (aPAD) for CPF of 1.7 mg/kg/day 

was exceeded by one child who consumed 10 cherry tomatoes that contained 30 ng/g azinphosmethyl and 

350 ng/g CPF. This child’s cumulative 

daily dose of CPF equivalents was 

estimated to be 2.5 mg/kg/day (Fenske et al., 2002). Diazinon and CPF 

were commonly detected in indoor 

air. Most housedust samples contained one or more OP pesticide. OP 

pesticides were virtually non-detectable in drinking water and soil. Clear

differences were noted in the

exposure pathways for the rural

agricultural children and Seattle

metropolitan area children, with

metabolite levels in suburban

children being correlated with

reported household pesticide use

(Lu et al., 2004).

When four urine samples were 

collected from each child over the 

course of a 24-hour period, the data 

were highly variable, suggesting a 

single spot sample is not a reliable 

predictor of an individual child’s 

exposure. First morning void samples 

were found to be the best predictors 

of total daily metabolite excretion 

(Griffith et al., submitted and Kissel 

et al., 2005). In the fourth field

study, children with organic diets

were found to have significantly

lower median dimethyl DAP levels

than did children consuming

conventional diets. No differences

in occupational or household pesticide use were reported between

the two groups (Curl et al., 2003).

The researchers also developed a 

novel method for determination 

of OP pesticide concentrations 

in household and vehicle dust. 

This method used size exclusion 

chromatography (SEC) as a cleanup 

method for the analysis of organophosphorus pesticides diazinon, 

methyl parathion, CPF, MDA, phosmet, and azinphosmethyl (Moate 

et al., 1999).

PI: 

Dr. Richard Fenske, 

University of Washington

EPA Grant Number: 

R825171

Amount: 

$600,145 

Duration: 

September 1996 to September 2000
12

3.1	 Contributions to ORD

Research Goals

All of the research contained in 

this report has helped to reduce 

uncertainties in risk assessment by 

providing better data on children’s 

aggregate exposures and estimation of exposure factors, improving 

knowledge of children’s pesticide 

exposure in agricultural communities, helping to identify principles 

for the use of scaling factors in risk 

assessment, and developing and 

validating biomarkers of exposure 

and dose. For convenience, grants 

are referred to in this section by the 

name of the first PI listed on the 

grant proposal. (Richard Fenske and 

Mary Kay O’Rourke were the PI on 

more than one grant; these grants 

are also referred to by number). 

Four of the grants (Fenske 825171, 

O’Rourke 827443 and 825169, and 

Sexton) specifically involved measurements of aggregate pesticide 

exposures from multiple sources 

in different selected populations 

of children. Fenske looked at 

multipathway exposures in children 

in Washington State in relation to 

urban/rural residence, household 

and agricultural pesticide usage, 

versus parental and other household variables. Both of O’Rourke’s

grants evaluated pesticide exposures in predominantly Hispanic 

rural communities near the U.S./

Mexico border in relation to pesticide levels in soil, house dust, and 

activity patterns. Sexton evaluated 

exposure patterns of children in 

urban and rural Minnesota communities. Multipathway aggregate 

exposures (air, soil, dust, diet, surfaces) were measured using urinary 

metabolites as biomarkers.

Shalat evaluated the factors contributing to children’s ingestion 

exposures to OP pesticides, also in 

New Mexico. O’Rourke (825169) 

estimated OP exposures in children 

in Arizona, and evaluated the relative 

contributions of dermal and ingestion pathways to total exposure. 

Whyatt’s analysis of meconium 

samples and maternal exposure 

levels will help characterize prenatal OP pesticide exposure patterns 

among minority infants in New York 

City. Wilkens’ longitudinal study is 

examining maternal, prenatal, and 

postnatal biomarkers of exposuure 

that support analysis of aggregate 

exposures to OP and pyrethoid 

pesticides and may reveal age-related 

exposure differences. His work will 

also attempt to correlate biomarkers 

of exposure with impaired development in the exposed infants.

Along with Sexton, both Shalat

and O’Rourke (827443) evaluated 

children’s mouthing behaviors and 

found that they contributed significantly to aggregate exposures. 

Raymer evaluated levels of pesticide 

metabolites in urine from populations in rural Minnesota, finding 

that metabolite levels were much 

higher in children than in adults, 

and higher in younger children than 

in older children in similar exposure 

settings. Chambers developed a 

method for measuring the potential dermal exposures and doses in 

children and adult dog owners who 

use pesticide flea dips or collars 

and found that such exposures may 

contribute significantly to household 

pesticide exposures. These results 

are directly applicable to pesticide 

risk assessments.

Many of these grants provided information about children’s exposures, 

body burdens and dose levels that 

could be used in conjunction with 

other data for comparison with 

adults’ exposure patterns. Raymer’s

research specifically documented 

higher children’s pesticide exposures 

and doses and higher exposures 

in younger children than in older 

children in similar exposure settings. 

Wilkins is engaged in a long-term 

study of maternal, prenatal, and 

postnatal pesticide exposures and 

body burdens. Whyatt’s study is also 

evaluating and comparing indices 

of maternal and prenatal exposure. 

Finally, the PBPK modeling efforts of 

Timchalk and Tessari provide frameworks that may ultimately be used 

to compare children and adult body 

burdens of CPF and ATRA, respectively. Chambers compared adults’ 

and children’s levels of urinary pesticide metabolites in households with 

CPF-collared dogs.

3. Contributions to ORD Research Goals and State of Knowledge
13

Research under many of the grants 

has indirectly provided information 

that could be used in development 

of scaling factors for risk assessment 

(that is, for adjusting between adults 

and children). Data from the research 

that evaluated relationships between 

children and adult exposures and 

body burdens (Raymer, Whyatt) 

may find direct application in risk 

assessments for pesticide exposures. 

Data being developed by Wilkins on 

indices of maternal and infant body 

burdens of pesticides might also 

be used. Shalat evaluated methods 

for evaluating dermal and ingestion 

exposures based on children’s body 

(hand) size and behavior patterns, 

and O’Rourke (827443) investigated 

the behavior and physical determinants (including gender) of children’s pesticide exposure patterns. 

In addition, the PBPK models developed by Timchalk and Tessari are 

intended to help elucidate relationships between adult and children’s 

exposures, absorbed doses, and 

adverse effects. 

Grants involving PBPK modeling 

helped to understand differences 

between children and adults. Timchalk and Fenske (828606) developed and/or refined PBPK models 

for OP pesticides to improve their 

applicability in human health risk 

assessments for adults and children. 

Timchalk developed analytical 

methods and conducted in vivo

and in vitro experiments on CPF 

metabolism to improve a previously 

developed PBPK-PD model. Studies 

of enzyme polymorphism on CPF 

metabolism, and on the role of firstpass metabolism in the intestine on 

absorbed dose, were used to improve 

the ability of the model to replicate 

serum time-course data. In addition, the refined model was used to 

establish the utility of saliva esterase 

inhibition as a useful biomarker of 

CPF exposure. 

Fenske (828606) used data from 

rat studies to develop a pharmacokinetic model for diazinon and its 

metabolites. The model confirmed 

the utility of saliva metabolite levels 

as indicators of exposure. 

Tessari developed the first 

metabolite-specific PBPK model for 

ATRA. Tessari’s model incorporates 

dealkylation by cytochrome 

P450 isozymes and glutathione 

conjugation, as well as binding to 

hemoglobin and serum proteins. 

The model is intended for use in 

evaluating hair protein adducts 

as biomarkers of exposure and 

as potential risk indicators. This 

model may help to better elucidate 

the as yet poorly understood 

pharmacodynamic mechanisms of 

ATRA and its metabolites in humans.

The five studies funded under the 

biomarkers RFA were specifically 

devoted to biomarker identification 

and validation, and all attempt to 

improve risk assessment through 

biomarker use, and to develop more 

convenient, less invasive biomarkers 

of exposure. Wilkins conducted a 

detailed evaluation of a wide range 

of maternal and neonatal biomarkers of pesticide exposure as predictors of infants’ neurodevelopmental 

impairment. Fenske (828606) and 

Timchalk used animal experiments 

and PBPK modeling to evaluate the 

usefulness of diazinon metabolites 

and cholinesterase levels, respectively, in saliva as noninvasive indicators of pesticide exposures and risks. 

Whyatt evaluated the use of OP 

metabolite levels in meconium as 

a noninvasive indicator of prenatal 

pesticide exposures. The PBPK model 

developed by Tessari could be used 

in pesticide risk assessments and is 

also intended for use in validating 

hair protein adducts as a noninvasive 

biomarker of ATRA exposure. Five 

studies that measured children’s 

exposures (Raymer, Shalat,

O’Rourke—both grants, Sexton,

and Fenske 825171) evaluated 

correlations between environmental samples, noninvasive personal 

exposure samples (hand rinses and 

wipes), and more conventional biomarkers (urine metabolite analyses). 

Wilkins, Sexton, O’Rourke—both 

grants, and Fenske (R825171) supported development and validation 

of urinary metabolites as biomarkers 

of exposure to pesticides.

In summary, these research grants 

contributed to our knowledge of 

children’s pesticide exposures, 

including pathways, types of 

pesticides, and age-related differences. This research also helps 

us understand differences in 

exposure between children and 

adults. Finally, it has increased 

our understanding of children’s 

pesticide exposures in agricultural 

communities.

This research will be beneficial for 

risk assessments, for models that help 

quantify biomarkers of exposure, and 

for the identification and validation 

of novel biomarkers.
14

3.2	 Summary of Major Contributions

to the State of Knowledge

All three of the RFAs resulted in 

research that contributed significantly 

to the state of knowledge related to 

children’s pesticide exposures and 

risks. Major contributions include: 

Biomarkers for the Assessment of 

Exposure and Toxicity in Children

• Novel Biomarkers. Three studies 

investigated novel, noninvasive 

biomarkers of children’s exposure, including saliva (diazinon 

metabolites, and cholinesterase 

inhibition by CPF), meconium 

(third-trimester cumulative exposure to OP pesticides), and 

hair protein adducts (ATRA and 

metabolites).

• PBPK Validation and Support of 

Biomarkers. Some of the studies discussed above included 

the evaluation and validation of 

biomarkers as part of comprehensive PBPK frameworks that may 

be used in future risk assessments 

for children’s exposure to pesticides. These studies also suggest 

mechanistic and methodological 

approaches for future validation of 

children’s biomarkers of exposure. 

Children’s Vulnerability to Toxic 

Substances in the Environment

• Ubiquity of Pesticide Contamination and Exposure. Studies

under this RFA found uniformly

high frequencies of pesticide

contamination in household

dust and surface wipes, confirming the ubiquity of household sources of children’s pesticide exposure. The frequency of 

detection of pesticide metabolites 

in urine approached 100 percent 

in some populations. 

• High Variability in Children’s 

Pesticide Exposures. Levels of 

household pesticide contamination and biomarkers of children’s 

exposure were found to be highly 

variable among households and 

individuals, with most subjects 

experiencing low exposures, while 

a few were highly exposed. The

most highly exposed children

were found to have received

estimated pesticide doses that

exceeded health-based criteria

in two instances. These studies

demonstrated the need to thoroughly characterize population

exposures to avoid potentially

hazardous exposures, even

where most exposures are low. 

• Importance of Mouthing and 

Other Behaviors. Results of several 

studies established quantitatively 

what had been suspected but 

not conclusively established, that 

mouthing behavior in young 

children is an important factor 

in determining total household 

exposure to pesticides. One study

showed that this risk is not

reduced by normal hygiene

practices, a finding that has

important implications for the

design of strategies to reduce

children’s pesticide exposures.

Exposure of Children to Pesticides

• Estimation of Aggregate Exposures. Grants under this RFA 

funded four major studies of cohorts of children in different areas 

of the country, in different ethnic 

groups, and in urban, rural, and 

agricultural areas. 

• Sources of Exposure. The studies 

addressed the relative importance 

of different sources of exposures, 

behaviors that contributed to 

exposures, and socieconomic, 

parental, and household variables. 

• Relative Exposures of Children 

and Adults. Two of the studies 

compared children’s and adults’ 

exposure patterns, exposure levels, and biomarkers of exposure 

in such a way that inferences can 

be drawn regarding potential risk 

differences by age.

In summary, the grants evaluated in 

this report have resulted in a number of important advances in the 

state of knowledge relating to children’s pesticide exposures. Research 

under these grants has added greatly 

to the available data on children’s 

pesticide exposure patterns and 

potential risks, the usefulness of 

biomarkers of pesticide exposure, 

and identified major methodological 

and data gaps in risk assessment for 

children’s pesticide exposures. 
15

4. Cited References

Adgate JL, Barr DB, Clayton CA, 

Eberly LE, Freeman NC, Lioy 

PJ, Needham LL, Pellizzari ED, 

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. Environmental Health 

Perspectives, 109(6):583–590.

Adgate JL, Kukowski A, Stroebel C, 

Shubat PJ, Morrell S, Quackenboss JJ, Whitmore RW, Sexton 

K. (2000). Pesticide storage 

and use patterns in Minnesota 

households with children. Journal of Exposure Analysis and 

Environmental Epidemiology, 

10(2):159–167.

Boone JS, Tyler JW, and Chambers 

JE. (2001). Transferable residues from dog fur and plasma 

cholinesterase inhibition in 

dogs treated with a flea control 

dip containing chlorpyrifos. 

Environmental Health Perspectives,109:1109–1114.

Brzezicki JM, Tessari JD, Andersen 

ME, and Cranmer BK. (2003). 

Quantitative identification of 

atrazine and its chlorinated 

metabolites in plasma. Journal 

of Analytical Toxicology, 20 

(November/December):569–573.

Clayton AC, Pellizzari ED, Whitmore 

RW, Quackenboss JJ, Adgate J, 

and Sefton K. (2003). Distributions, associations, and partial 

aggregate exposure of pesticides 

and polynuclear aromatic hydrocarbons in the Minnesota Children’s Pesticide Exposure Study 

(MNCPES). Journal of Exposure 

Analysis and Environmental 

Epidemiology, 13(2):100–111. 

Curl CL, Fenske RA, and Elgethun 

K. (2003). Organophosphorus 

pesticide exposure of urban and 

suburban preschool children 

with organic and conventional 

diets. Environmental Health 

Perspectives, 111(3):377–382.

DHHS (United States Department 

of Health and Human Services). (1996). National Center 

for Health Statistics. Third 

National Health and Nutrition 

Examination Survey, 1988–1994. 

NHANES III Laboratory Data File 

(CD-ROM). Public Use Data File 

Documentation Number 76200. 

Centers for Disease Control and 

Prevention, Hyattsville, MD.

Environmental Protection Agency 

(EPA). (2003). Human Health 

Research Strategy. Office of 

Research and Development, 

September.

EPA (2003). Human Health MultiYear Plan. Office of Research 

and Development, April.

Fenske RA, Kedan G, Lu C, FiskerAndersen JA, and Curl CL. 

(2002). Assessment of organophosphorus pesticide exposures in the diets of preschool 

children in Washington State. 

Journal of Exposure Analysis 

and Environmental Epidemiology, 12:21–28.

Freeman NC, Jimenez M, Reed KJ, 

Gurunathan S, Edwards RD, 

Roy A, Adgate JL, Pellizzari ED, 

Quackenboss J, Sexton K, and 

Lioy PJ. (2001). Quantitative 

analysis of children’s microactivity patterns: The Minnesota children’s pesticide exposure study. 

Journal of Exposure Analysis 

and Environmental Epidemiology, 11(6):501–509. 

Griffith W, Curl CL, Fenske RA, Koch 

D, and Lu CA. Organophosphorus pesticide metabolite levels 

in pre-school children in an agricultural community: Within- and 

between-child variability in a longitudinal study. Environmental 

Health Perspectives (Submitted).

Kissel JC, Curl CL, Kedan G, Lu CA, 

Griffith W, Barr DB, Needham 

LL, and Fenske RA. (2005). 

Comparison of organophosphorus pesticide metabolite levels 

in single and multiple daily 

urine samples collected from 

pre-school children in Washington State. Journal of Exposure 

Analysis and Environmental 

Epidemiology 15(2):164–171.
16

Koch D, Lu C, Jolley L, Fenske R. 

(2002). Longitudinal biological 

monitoring of organophosphorous pesticide exposure among 

children living in an agricultural 

community. Environmental 

Health Perspective 110(8):

829–833.

Kousba AA, Poet TS, and Timchalk C. 

(2003). Characterization of the 

in vitro kinetic interaction of 

chlorpyrifos-oxon with rat salivary cholinesterase: A potential 

biomonitoring matrix. Toxicology, 188(2):219–232. 

Lioy PJ, Edwards RD, Freeman N, 

Gurunathan S, Pellizzari E, 

Adgate JL, Quackenboss J, and 

Sexton K. (2000). House dust 

levels of selected insecticides 

and a herbicide measured by 

the EL and LWW samplers and 

comparisons to hand rinses 

and urine metabolites. Journal of Exposure Analysis and 

Environmental Epidemiology,10(4):327–340. 

Lu C, Kedan G, Fisker-Andersen, J, 

Kissel JC, and Fenske RA. (2004). 

Multi-pathway organophosphorus pesticide exposures of 

pre-school children living in 

agricultural and nonagricultural 

communities. Environmental 

Research, 96(3):283–289.

Lu C, Irish RM, and Fenske RA. 

(2003). Biological monitoring of 

diazinon exposure using saliva 

in an animal model. Journal of 

Toxicology and Environmental 

Health, Part A, 66:2315–2325.

Lu C, Knutson D, Fisker-Anderson 

J, Fenske R. (2001). Biological 

monitoring survey of organophosphorus pesticide exposure 

among pre-school children in 

the Seattle metropolitan area. 

Environmental Health Perspective 109(3):299–303.

McMullin TS, Brzezick JM, Cranmer 

BK, Tessari JD, and Andersen 

ME. (2003). Pharmacokinetic 

modeling of disposition and 

time-course studies with 

[C-14] atrazine. Journal of Toxicology and Environment Health,

Part A, 66(10):941–964.

Moate TF, Lu C, Fenske RA, Hahne 

RM, and Kalman DA. (1999). 

Improved cleanup and determination of dialkyl phosphates in 

the urine of children exposed to 

organophosphorus insecticides. 

Journal of Analytical Toxicology, 23(4):230–236.

O’Rourke MK, Lizardi PS, Rogan SP, 

Freeman NC, Aguirre A, and 

Saint CG. (2000). Pesticide exposure and creatinine variation 

among young children. Journal 

of Exposure Analysis and Environmental Epidemiology, 10(6 

Pt 2):672–681. 

Poet TS, Wu H, Kousba AA, and 

Timchalk C. (2003). In vitro rat 

hepatic and enterocyte metabolism of the organophosphate 

pesticides chlorpyrifos and 

diazinon. Toxicological Sciences,

72(1):193–200.

Quackenboss JJ, Pellizzari ED, 

Shubat P, Whitmore RW, Adgate 

JL, Thomas KW, Freeman NC, 

Stroebel C, Lioy PJ, Clayton AC, 

and Sexton K. (2000). Design 

strategy for assessing multipathway exposure for children: 

The Minnesota Children’s Pesticide Exposure Study (MNCPES). 

Journal of Exposure Analysis 

and Environmental Epidemiology, 10(2):145–158.

Sexton K, Adgate JL, Eberly LE, Clayton CA, Whitmore RW, Pellizzari 

ED, Lioy PJ, and Quackenboss 

JJ. (2003). Predicting children’s 

short-term exposure to pesticides: Results of a questionnaire 

screening approach. Environmental Health Perspectives,

111(1):123–128. 

Shalat SL, Donnelly KC, Freeman NC, 

Calvin JA, Ramesh S, Jimenez M, 

Black K, Coutinho C, Needham 

LL, Barr DB, and Ramirez J. 

(2003). Non-dietary ingestion 

of pesticides by children in an 

agricultural community on the 

US/Mexico border: Preliminary 

results. Journal of Exposure 

Analysis and Environmental 

Epidemiology, 13:42–50. 

Timchalk CT, Poet S, Kousba AA, 

Campbell JA, and Lin Y. (2004). 

Non-invasive biomonitoring 

approaches to determine dosimetry and risk following acute 

chemical exposure: Analysis 

of lead and organophosphate 

insecticide in saliva. Journal of 

Toxicology and Environmental 

Health, Part A. 67:635–650.

Timchalk C, Kousba A, and Poet TS. 

(2002). Monte Carlo analysis of 

the human chlorpyrifos-oxonase 

(PON1) polymorphism using a 

physiologically based pharmacokinetic and pharmacodynamic 

(PBPK-PD) model. Toxicology 

Letters, 135(1):51–59.

Whyatt RM, Barr DB, Camann DE, 

Barr JR, Andrews HF, Hoepner 

LA, Kinney PL, and Perera 

FP. (2003). Measurement of 

contemperary-use pesticides 

in personal air samples during 

pregnancy and blood samples 

at delivery among urban minority mothers and newborns. 

Environmental Health Perspectives, 111(5):749–756.
17

5. Additional Grant Publications

Chambers, EPA Grant Number:

R825170

Boone JS, Tyler JW, and Chambers, 

JE. (2001). Transferable residues from dog fur and plasma 

cholinesterase inhibition in dogs 

treated with a flea control dip 

containing chlorpyrifos. Environmental Health Perspectives,

109:1109–1114.

Fenske, EPA Grant Number:

R825171

Curl CL, Fenske RA, and Elgethun 

K. (2003). Organophosphorus 

pesticide exposure of urban and 

suburban preschool children 

with organic and conventional 

diets. Environmental Health 

Perspectives, 111(3):377–382.

Fenske RA, Kedan G, Lu C, FiskerAndersen JA, and Curl CL. 

(2002). Assessment of organophosphorus pesticide exposures in the diets of preschool 

children in Washington State. 

Journal of Exposure Analysis 

and Environmental Epidemiology, 12:21–28.

Fenske RA, Lu C, Simcox NJ, Loewenherz C, Touchstone J, Moate TF, 

Allen EH, Kissel JC. (2000). 

Strategies for assessing children’s 

organophosphorus pesticide 

exposures in agricultural communities. Journal of Exposure 

Analysis and Environmental 

Epidemiology, 10:662–671.

Griffith W, Curl CL, Fenske RA, Koch 

D, and Lu CA. Organophosphorus pesticide metabolite levels 

in pre-school children in an agricultural community: Within- and 

between-child variability in a longitudinal study. Environmental 

Health Perspectives (Submitted).

Kissel JC, Curl CL, Kedan G, Lu CA, 

Griffith W, Barr DB, Needham LL, 

and Fenske RA. (2005). Comparison of organophosphorus 

pesticide metabolite levels in 

single and multiple daily urine 

samples collected from preschool children in Washington 

State. Journal of Exposure 

Analysis and Environmental 

Epidemiology, 

15(2):164–171.

Koch D, Lu C, Jolley L, Fenske R. 

(2002). Longitudinal biological 

monitoring of organophosphorous pesticide exposure among 

children living in an agricultural 

community. Environmental 

Health Perspective 110(8):

829–833.

Lu C, Kedan G, Fisker-Andersen, J, 

Kissel JC, and Fenske RA. (2004).

Multi-pathway organophosphorus pesticides exposures 

of pre-school children living in 

agricultural and nonagricultural 

communities. Environmental 

Research, 96(3):283–289.

Lu C, Knutson D, Fisker-Anderson 

J, Fenske R. (2001). Biological 

monitoring survey of organophosphorus pesticide exposure 

among pre-school children in 

the Seattle metropolitan area. 

Environmental Health Perspective 109(3):299–303.

Moate TF, Lu C, Fenske RA, Hahne 

RM, and Kalman DA. (1999). 

Improved cleanup and determination of dialkyl phosphates in 

the urine of children exposed to 

organophosphorus insecticides. 

Journal of Analytical Toxicology,

23(4):230–236.

Fenske, EPA Grant Number:

R828606

Lu C, Rodriguez T, Funez A, and 

Fenske RA. (2006). The assessment of occupational exposure 

to diazinon in Nicaraguan 

plantation workers using saliva 

biomonitoring. Annals of the 

New York Academy of Sciences, 

1076:355-365.

Lu C, Showlund-Irish R, and Fenske 

R. (2003). Biological monitoring 

of diazinon exposure using saliva 

in an animal model. Journal of 

Toxicology and Environmental 

Health, 66:2315–2325.

Rodriguez T, Younglove L, Lu C, Funez 

A, Weppner S, Barr DB, and 

Fenske RA. (2006). Biological 

monitoring of pesticide exposure 

among applicators and their children in Nicaragua. International 

Journal of Occupational and 

Environmental Health, 12(4): 

312-320.
18

Sexton, EPA Grant Number:

R825283

Adgate JL, Barr DB, Clayton CA, 

Eberly LE, Freeman NC, Lioy 

PJ, Needham LL, Pellizzari ED, 

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. Environmental Health 

Perspectives,109(6):583–590.

Adgate JL, Kukowski A, Stroebel C, 

Shubat PJ, Morrell S, Quackenboss JJ, Whitmore RW, Sexton 

K. (2000). Pesticide storage 

and use patterns in Minnesota 

households with children. Journal of Exposure Analysis and 

Environmental Epidemiology, 

10(2):159–167.

Clayton AC, Pellizzari ED, Whitmore 

RW, Quackenboss JJ, Adgate J, 

Sexton K. (2003). Distributions, 

associations, and partial aggregate exposure of pesticides and 

polynuclear aromatic hydrocarbons in the Minnesota Children’s Pesticide Exposure Study 

(MNCPES). Journal of Exposure 

Analysis and Environmental 

Epidemiology, 13(2):100–111.

Freeman NC, Jimenez M, Reed KJ, 

Gurunathan S, Edwards RD, 

Roy A, Adgate JL, Pellizzari ED, 

Quackenboss J, Sexton K, and 

Lioy PJ. (2001). Quantitative 

analysis of children’s microactivity patterns: The Minnesota 

Children’s Pesticide Exposure 

Study. Journal of Exposure 

Analysis and Environmental 

Epidemiology, 11(6):501–509.

Lioy PJ, Edwards RD, Freeman N, 

Gurunathan S, Pellizzari E, 

Adgate JL, Quackenboss J, and 

Sexton K. (2000). House dust 

levels of selected insecticides 

and a herbicide measured by 

the EL and LWW samplers and 

comparisons to hand rinses 

and urine metabolites. Journal of Exposure Analysis and 

Environmental Epidemiology,

10(4):327–140. 

Quackenboss JJ, Pellizzari ED, 

Shubat P, Whitmore RW, Adgate 

JL, Thomas KW, Freeman NC, 

Stroebel C, Lioy PJ, Clayton AC, 

and Sexton K. (2000). Design 

strategy for assessing multi-pathway exposure for children: The 

Minnesota Children’s Pesticide 

Exposure Study (MNCPES). Journal of Exposure Analysis and 

Environmental Epidemiology,

10(2):145–158.

Sexton K, Adgate JL, Eberly LE, Clayton CA, Whitmore RW, Pellizzari 

ED, Lioy PJ, and Quackenboss 

JJ. (2003) Predicting children’s 

short-term exposure to pesticides: Results of a questionnaire 

screening approach. Environmental Health Perspectives,

111(1):123–128. 

Shalat, EPA Grant Number:

R827440

Shalat SL, Donnelly KC, Freeman NC, 

Calvin JA, Ramesh S, Jimenez M, 

Black K, Coutinho C, Needham 

LL, Barr DB, and Ramirez J. 

(2003). Non-dietary ingestion 

of pesticides by children in an 

agricultural community on the 

US/Mexico border: Preliminary 

results. Journal of Exposure 

Analysis and Environmental 

Epidemiology, 13:42–50. 

Tessari (previously Andersen),

EPA Grant Number: R828610

Brzezicki JM, Tessari JD, Andersen 

ME, and Cranmer BK. (2003). 

Quantitative identification of 

atrazine and its chlorinated 

metabolites in plasma. Journal 

of Analytical Toxicology, 20 

(November/December):569–573. 

McMullin TS, Andersen ME, Nagahara 

A, Lund TD, Pak T, Handa RJ, 

and Hanneman WH. (2004). Evidence that atrazine and diaminochlorotriazine inhibit the 

estrogen/progesterone induced 

surge of luteinizing hormone 

in female Sprague-Dawley rats 

without changing estrogen 

receptor action. Toxicological 

Sciences, 79:278–286.

McMullin TS, Brzezick JM, Cranmer 

BK, Tessari JD, and Andersen 

ME. (2003). Pharmacokinetic 

modeling of disposition and 

time-course studies with [C14]atrazine. Journal of Toxicology and Environment Health,

Part A, 66(10):941–964.

Tessari JD and Cranmer BK. Analytical 

determination of atrazine and its 

chlorinated metabolites in rodent 

brain tissue. Journal of Analytical Toxicology (Submitted).
19

Timchalk, EPA Grant Number:

R828608

Kousba AA, Poet TS, and Timchalk C. 

(2003). Characterization of the 

in vitro kinetic interaction of 

chlorpyrifos-oxon with rat salivary cholinesterase: A potential 

biomonitoring matrix. Toxicology,188(2):219–232. 

Poet TS, Wu H, Kousba AA, and 

Timchalk C. (2003). In vitro rat 

hepatic and enterocyte metabolism of the organophosphate 

pesticides chlorpyrifos and 

diazinon. Toxicological Sciences,

72(1):193–200.

Timchalk CT, Poet S, Kousba AA, 

Campbell JA, and Lin Y. (2004). 

Non-invasive biomonitoring 

approaches to determine dosimetry and risk following acute 

chemical exposure: Analysis 

of lead and organophosphate 

insecticide in saliva. Journal of 

Toxicology and Environmental 

Health, Part A, 67:635–650.

Timchalk C, Kousba A, and Poet TS. 

(2002). Monte Carlo analysis of 

the human chlorpyrifos-oxonase 

(PON1) polymorphism using a 

physiologically based pharmacokinetic and pharmacodynamic 

(PBPK-PD) model. Toxicology 

Letters, 135(1):51–59.

Whyatt, EPA Grant Number:

R828609

Bradman A and Whyatt RM. (2005). 

Characterizing exposures to 

nonpersistent pesticides during 

pregnancy and early childhood in the National Children’s 

Study: A review of monitoring 

and measurement technologies.

Environmental Health Perspectives, 113(8):1092–1099.

Fenske RA, Bradman A, Whyatt RM, 

Wolff MS, and Barr DB. (2005). 

Lessons learned for the assessment of children’s pesticide 

exposure: Critical sampling 

and analytical issues for future 

studies. Environmental Health 

Perspectives 113(10):1455–1462.

Whyatt RM, Camann DE, Perera FP, 

Rauh VA, Tang D, Kinney PL, Garfinkel R, Andrews H, Hoepner 

L, and Barr DB. (2005). Biomarkers in assessing residential 

insecticide exposures during 

pregnancy and effects on fetal 

growth. Toxicology and Applied 

Pharmacology, 206(2):246–254.

Whyatt RM, Rauh V, Barr DB, Camann 

DE, Andrews HF, Garfinkel R, 

Hoepner LA, Diaz D, Dietrich 

J, Reyes A, Tang D, Kinney PL, 

and Perera FP. (2004). Prenatal 

insecticide exposure and birth 

weight and length among an 

urban minority cohort. Environmental Health Perspectives, 

112(10):1125–1132.

Whyatt RM, Barr DB, Camann DE, 

Barr JR, Andrews HF, Hoepner 

LA, Kinney PL, and Perera 

FP. (2003). Measurement of 

contemporary-use pesticides 

in personal air samples during 

pregnancy and blood samples 

at delivery among urban minority mothers and newborns. 

Environmental Health Perspectives, 111(5):749–756.

Whyatt RM, Camann DE, Barr DB, 

Barr JR, Andrews HF, Hoepner 

LA, Kinney PL, and Perera FP.

(2002). Pesticides levels in 

48-hour personal air samples 

during pregnancy and in blood 

samples at delivery from urban 

minority mothers and newborns.

Proceedings of the 9th International Conference on Indoor 

Air Quality and Climate (Ed. H. 

Levin), 4:877–882.
20
A-1

Appendix A. Cross-Walk of STAR Grant Contributions 

to ORD Research Goals and Specific Grant 

Contributions to These Goals 

Table A-1. Cross-walk of STAR Grant Contributions to ORD Research Goals

Biomarkers 

of Pesticide 

Exposure 

Children’s 

Vulnerability to 

Pesticides

Children’s 

Exposure to 

Pesticides

Research Objective, Human Health Multi-Year Plan

R828611 WilkinsR828608 TimchalkR828606 FenskeR828609 WhyattR828610 TessariR827440 ShalatR827444 RaymerR827443 O’RourkeR825169 O’RourkeR825283 SextonR825170 ChambersR825171 Fenske

APG 44. Provide better data on children’s 

aggregate exposures and estimation of 

exposure factors

H H H H H H H H H

APM 188. Provide information supporting the 

comparison of children’s and adult exposures 

and body burdens

H H H H H H

APM 187. Improve knowledge of children’s 

pesticide exposure in agricultural communities H H H H H H

APG 45. Help identify principles for the use of 

scaling factors in risk assessment H H H H H H H

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) 

models to quantify biomarkers of exposures to 

organophosphate pesticides 

H H

APM 376. Provide biomarkers and 

pharmocokinetic data that can be used in 

pesticide risk assessments under the Food 

Quality Protection Act

H H H H H H H H H H H

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks H H H H H H H H H H

More detailed tabular summaries of the contributions of each grant to meeting EPA ORD’s Annual Perfomance 

Goals (APGs) or Annual Performance Measures (APMs) in the areas of children’s exposure and risk assessment are 

provided in this appendix. The first column of table A-1 below lists these seven major research goals. Each column of 

the table identifies with a star the grants whose research has contributed significantly to the achievement of these goals.
A-2

Research Objective, Human Health Multi-Year Plan

EPA Grant Number R828611 (Wilkins) Biomarkers 

and Neurobehavioral Effects of Perinatal Exposure to 

Chlorpyrifos and Other Organophosphate Insecticides 

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

The study will provide biomarkers that indicate 

maternal, prenatal, and early aggregate exposures to a 

range of commonly used household pesticides.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Relative body burdens of household pesticides may 

be estimated from the study results.

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

The study results may support estimates of scaling 

factors for use in estimating pre- and postnatal 

pesticide exposures.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

The study will provide information concerning the 

relationships between biomarkers of specific pesticide 

exposures and adverse effects on neurological 

development, which may be applied in children’s risk 

assessments.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

The study can provide validation data in support of 

urinary metabolite analysis as biomarkers of exposure 

in infants, particularly for synthetic pyrethroids.
A-3

Research Objective, Human Health Multi-Year Plan

EPA Grant Number R828608 (Timchalk) Development of a 

PBPK-PD Model to Quantitate Biomarkers of Exposure for 

Organophosphate Insecticides

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors N/A

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Refined PBPK-PD model can be used to investigate 

differences in metabolism, adverse effects associated 

with age differences, enzyme polymorphisms.

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

Refined PBPK-PD model can be used to investigate 

differences in metabolism, adverse effects associated 

with age differences, enzyme polymorphisms. 

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

Developed data and PBPK model supporting the use 

of metabolite and cholinesterase measurement in 

saliva as biomarkers of OP pesticide exposure.

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Refined PBPK-PD model can be used in risk 

assessments for OP residues in foods as required 

under the FQPA.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Developed data supporting the use of metabolite and 

cholinesterase measurement in saliva as biomarkers of 

OP pesticide exposure.
A-4

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R828606 (Fenske) Saliva Biomonitoring 

for Organophosphorus Pesticide Exposures in Children

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors N/A

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment N/A

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

Developed exposure model using metabolites in 

saliva as biomarkers of pesticide exposure; could 

be integrated into PBPK model for estimation of 

exposures or target organ dose.

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Developed pharmacokinetic data on OP pesticide 

diazinon. Developed data supporting the use of saliva 

as a biomonitoring of OP pesticide exposure.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Developed data supporting the use of metabolite 

measurement in saliva as a biomarker of risk for OP 

pesticide exposure.
A-5

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R828609 (Whyatt) Measurement of NonPersistent Pesticides in Postpartum Meconium 

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Will help demonstrate prenatal exposure patterns of 

minority infants to OP pesticides. 

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Meconium analyses may turn out to be useful 

biomarkers of cumulative (time-integrated) exposures 

and body burdens during pregnancy. 

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

The results could ultimately be used to help evaluate 

age-specific (including prenatal) variations in 

exposure and body burden that could be used in risk 

assessment.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Meconium levels may shed light on prenatal exposure 

levels that could be used in risk assessment under the 

FQPA.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Meconium could be a useful noninvasive biomarker 

of cumulative exposure to OP pesticides and other 

chemicals.
A-6

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R828610 (Tessari; Previously Andersen) 

Chlorotriazine Protein Binding: Biomarkers of Exposure and 

Susceptibility

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors N/A

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Future development of the atrazine PBPK model 

could be used to evaluate age-specific differences in 

pharmacokinetics.

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

Future development of the atrazine PBPK model 

could be used to evaluate age-specific differences in 

pharmacokinetics.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A (Atrazine is not an OP)

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

The atrazine PBPK model could provide a framework 

for assessing potential children’s sensitivity to atrazine 

exposure, as required under the FQPA.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Further development of the model will allow 

evaluation of the feasibility of using hair protein 

adducts as a noninvasive biomarker for quantifying 

atrazine exposures.
A-7

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R827440 (Shalat) 

Ingestion of Pesticides by Children in an Agricultural 

Community on the U.S./Mexico Border

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of household exposures and 

determined dose levels.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Developed direct measurements of pesticide body 

burden and excretion rates in children living in rural 

areas.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

Data collected indicative of variations in pediatric 

pesticide exposures and body burdens between age 

groups.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Refined estimates of children’s exposures and doses 

of OP pesticide metabolites that can be used in 

risk assessments for pesticide residues in foods as 

required under the FQPA.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks N/A
A-8

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R827444 (Raymer) Study of Exposure 

and Body Burden of Children of Different Ages to Pesticides 

in the Environment

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of household exposures to 

pesticides.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Developed data establishing that children have higher 

body burdens of OP pesticide metabolites than adults.

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Developed direct measurements of pesticide body 

burden and excretion rates in children living in rural 

areas.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

Data collected indicative of variations in pediatric 

pesticide exposures and body burdens between age 

groups.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Refined estimates of children’s exposures and doses 

of OP metabolites that can be used in risk assessments 

for pesticide residues in foods as required under the 

FQPA.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Developed new noninvasive method for evaluating 

infant dermal contact exposures (body suits). Study 

provides data to support urinary metabolite analysis 

as biomarkers of exposure in children.
A-9

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R827443 (O’Rourke) Vulnerability 

of Young Children to OP Pesticides and Metals through 

Intermittent Exposures in Yuma, County, AZ

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of household exposure factors and 

determined exposure levels of children.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Developed direct measurements of pesticide residues 

in children living in agricultural areas.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment 

Data collected indicative of variations in pediatric 

pesticide exposures and body burdens between 

genders.

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Identified a urinary metabolite as a biomarker of 

exposure.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Developed data supporting the use of metabolite 

measurement in urine as a biomarker of risk for OP 

pesticide exposure.
A-10

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R825169 (O’Rourke) Exposure of 

Children to Pesticides in Yuma County, Arizona

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of pesticide exposure from dust, 

food, and beverages that were correlated with urine 

samples taken from children in Arizona from urban 

and agricultural areas.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Agricultural migrant communities in Yuma, Arizona, 

were compared to urban area.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment N/A

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Data collected on urinary metabolites (DAPs) 

from children in Yuma, Arizona, from urban and 

agricultural areas.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Urinary samples normalized with creatinine. Study 

supports the use of urinary metabolites as biomarkers 

of exposure in children.
A-11

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: R825283 (Sexton) 

Measuring and Apportioning Children’s Exposure to 

Pesticides in Urban, Suburban, and Rural Communities

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of pesticide exposure from dust, 

hand washing, indoor and outdoor air, food, and 

beverages, which were correlated with OP metabolites 

from urine samples taken from children in Minnesota 

from urban and agricultural areas.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Assessed rural/agricultural communities of Goodhue 

and Rice Counties for pesticide exposure and 

metabolism.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment N/A

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Dietary exposure assessed through analyzing food 

and beverage OP content and correlated with urinary 

metabolites (DAPs) for children in Minnesota from 

urban and agricultural areas.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Study provides data that support the use of urinary 

metabolites as biomarkers of exposure.
A-12

Research Objective, Human Health Multi-Year Plan

EPA Grant Number: 825170 (Chambers) Assessing Levels 

of Organophosphorus Insecticides Which Could Expose 

Children From Pets Treated with Flea Control Insecticides

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of pesticide exposure from dog flea 

controls.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

Compared urinary pesticide metabolites for 

chloropyrifos in households with chloropyrifos 

collared dogs.

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities N/A

APG 45. Help identify principles for the use of scaling 

factors in risk assessment N/A

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

N/A

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks N/A
A-13

Research Objective, Human Health Multi-Year Plan

EPA Grant Number R825171 (Fenske) Total 

Organophosphorus Pesticide Exposure among Children in 

Urban and Rural Environments

APG 44. Provide better data on children’s aggregate 

exposures and estimation of exposure factors

Quantified levels of pesticide exposure from dust, 

personal air, drinking water, and food, which was 

correlated with urine samples.

APM 188. Provide information supporting the 

comparison of children’s and adult exposures and 

body burdens

N/A

APM 187. Improve knowledge of children’s pesticide 

exposure in agricultural communities 

Assessed urban/agricultural communities of 

Washington State for pesticide exposure and 

metabolism.

APG 45. Help identify principles for the use of scaling 

factors in risk assessment N/A

APM 182. Development of physiologically based 

pharmacokinetic/pharmacodynamic (PBPK) models to 

quantify biomarkers of exposures to organophosphate 

pesticides 

N/A

APM 376. Provide biomarkers and pharmocokinetic 

data that can be used in pesticide risk assessments 

under the Food Quality Protection Act

Six dialkylphosphates were analyzed in children’s 

urine from various ages, genders, time points, 

geographical areas, and from children who consumed 

different diets. Duplicate diets were analyzed for 15 

OP pesticides.

APM 206. Develop less invasive biomarkers for 

assessing children’s exposures and risks

Study can provide data to support urinary metabolite 

analysis as biomarkers of exposure in children.


Recycled/Recyclable

Printed with Vegetable Oil Based Inks on Recycled Paper

(Minimum 50% Postconsumer) Process Chlorine Free

Office of Research and Development (8101R)

Washington, DC 20460

EPA/600/S-06/006

December 2006

www.epa.gov