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Summary
We are exposed every day to agents that have the potential to affect our
health--through the personal products we use, the water we drink, the food we
eat, the soil and surfaces we touch, and the air we breathe. Exposure science
addresses the intensity and duration of contact of humans or other organisms
with those agents (defined as chemical, physical, or biologic stressors)1 and their
fate in living systems. Exposure assessment, an application of this field of sci-
ence, has been instrumental in helping to forecast, prevent, and mitigate expo-
sures that lead to adverse human health or ecologic outcomes; to identify popu-
lations that have high exposures; to assess and manage human health and
ecosystem risks; and to protect vulnerable and susceptible populations.
Exposure science has applications in public health and ecosystem protec-
tion, and in commercial, military, and policy contexts. It is central to tracking
chemicals and other stressors that are introduced into global commerce and the
environment at increasing rates, often with little information on their hazard
potential. Exposure science is increasingly used in homeland security and in the
protection of deployed soldiers. Rapid detection of potentially harmful radiation
or hazardous chemicals is essential for protecting troops and the general public.
The ability to detect chemical contaminants in drinking water at low but
biologically relevant concentrations quickly can help to identify emerging health
threats, and monitoring of harmful algal blooms and airborne pollen can help to
identify health-relevant effects of a changing climate. With regard to policy and
regulatory decisions, exposure information is critical in budget-constrained
times for assessing the value of proposed public-health actions.
Exposure science has a long history, having evolved from such disciplines
as industrial hygiene, radiation protection, and environmental toxicology into a
theoretical and practical science that includes development of mathematical
models and other tools for examining how individuals and populations come
into contact with environmental stressors. Exposure science has played a
fundamental role in the development and application of many fields related to
1
Examples include chemical (toluene), biologic (Mycobacterium tuberculosis), and
physical (noise) stressors.
3
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4 Exposure Science in the 21st Century: A Vision and A Strategy
environmental health, including toxicology, epidemiology, and risk assessment.
For example, exposure information is critical in the design and interpretation of
toxicology studies and is needed in epidemiology studies to compare outcomes
in populations that have different exposure levels. Collection of better exposure
data can provide more precise information regarding risk estimates and lead to
improved public-health and ecosystem protection. For example, exposure
science can improve characterization of populationwide exposure distributions,
aggregate and cumulative exposures, and high-risk populations. Advancing and
promoting exposure science will allow it to have a more effective role in toxi-
cology, epidemiology, and risk assessment and to meet growing needs in
environmental regulation, urban and ecosystem planning, and disaster manage-
ment.
The committee identified emerging needs for exposure information. A
central example is the knowledge gap resulting from the introduction of thou-
sands of new chemicals into the market each year. Another example is the in-
creasing need to address health effects of low-level exposures to chemical, bio-
logic, and physical stressors over years or decades. Market demands also require
the identification and control of exposures resulting from the manufacture, dis-
tribution, and sale of products. Societal demands for exposure data arise from
the aspirations of individuals and communities--relying on an array of health,
safety, and sustainability information--for example, to maintain local environ-
ments, personal health, the health of workers, and the global environment.
Recently, a number of activities have highlighted new opportunities for
exposure science. For example, increasing collection and evaluation of bio-
marker data through the Centers for Disease Control and Prevention National
Health and Nutrition Examination Survey and other government efforts offer a
potential for improving the evaluation of sourceexposure and exposuredisease
relationships. The development of the "exposome", which conceptualizes that
the totality of environmental exposures (including such factors as diet, stress,
drug use, and infection) throughout a person's life can be identified, offers an
intriguing direction for exposure science. And the publication of two recent Na-
tional Research Council reports--Toxicity Testing in the 21st Century: A Vision
and a Strategy (2007) and Science and Decisions: Advancing Risk Assessment
(2009)--have substantially advanced conceptual and experimental approaches
in companion fields of toxicology and risk assessment while presenting tremen-
dous opportunities for the growth and development of exposure science.
The above activities have been made possible largely by advances in tools
and technologies--sensor systems, analytic methods, molecular technologies,
computational tools, and bioinformatics--over the last decade, which are pro-
viding the potential for exposure data to be more accurate and more comprehen-
sive than was possible in the past. The scientific and technologic advances also
provide the potential for the development of an integrated systems approach to
exposure science that is more fully coordinated with other fields of environ-
mental health; can address scientific, regulatory, and societal challenges better;
can provide exposure information to a larger swath of the population; and can
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Summary 5
embrace both human health and ecosystem protection. The availability of the
massive quantities of individualized exposure data that will be generated might
create ethical challenges and raise issues of privacy protection.
Recognizing the challenges and the need for a prospective examination of
exposure science, the U.S. Environmental Protection Agency (EPA) and the
National Institute of Environmental Health Sciences (NIEHS) asked the Na-
tional Research Council to develop a long-range vision and a strategy for im-
plementing the vision over the next 20 years, including development of a unify-
ing conceptual framework for the advancement of exposure science.2 In
response to the request, the National Research Council convened the Committee
on Human and Environmental Exposure Science in the 21st Century, which pre-
pared this report.
In this summary, the committee presents a roadmap of how technologic
innovations and strategic collaborations can move exposure science into the
future. It begins with a discussion of a new conceptual framework for exposure
science that is broadly applicable and relevant to all exposure media and routes,
reflecting the current and expected needs of the field. It then describes scientific
and technologic advances in exposure science. The committee next presents its
vision for advancing exposure science in the 21st century. Finally, it discusses
more broadly the elements needed to realize the vision, including research and
tool development, transagency coordination, education, and engagement of a
broad stakeholder community that includes government, industry, nongovern-
ment organizations, and communities.
CONCEPTUAL FRAMEWORK
Exposure science can be thought of most simply as the study of stressors,
receptors, and their contacts in the context of space and time. For example, eco-
systems are receptors for such stressors as mercury, which may cascade from the
ecosystem to populations to individuals in the ecosystem because of concentra-
tion and accumulation in the food web, which lead to exposure of humans and
other species. As the stressor (mercury in this case) is absorbed into the bodies
of organisms, it comes into contact with tissues and organs. It is important to
recognize that exposure science applies to any level of biologic organization--
ecologic, community, or individual--and, at the individual level, encompasses
external exposure (outside the person or organism), internal exposure (inside the
person or organism), and dose.
To illustrate the scope of exposure science and to embrace a broader view
of the role that it plays in human health and ecosystem protection, the committee
developed the conceptual framework shown in Figure S-1.
2
Given the committee's statement of task, it addressed primarily exposure-science
issues related to the U.S. and other developed countries.
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6 Exposure Science in the 21st Century: A Vision and A Strategy
FIGURE S-1 Conceptual framework showing the core elements of exposure science as
related to humans and ecosystems.
Figure S-1 identifies and links the core elements of exposure science:
sources of stressors, environmental intensity3 (such as pollutant concentrations),
timeactivity and behavior, contact of stressors and receptors, and outcomes of
the contact. The figure shows the role of upstream human and natural factors in
determining which stressors are mobilized and transported to key receptors.
(Examples of those factors are choosing whether to use natural gas or diesel
buses and choosing whether to pay more for gasoline and drive a car or to take a
bus--the choices influence the sources and can influence behavior.) The figure
indicates the role of the behavior of receptors and time in modifying contact,
depending on environmental intensities that influence exposure. Figure S-1 en-
capsulates both external and internal environments within the "exposure" box,
but indicates that exposure is measured at some boundary between source and
receptor. Dose is the amount of material that passes or otherwise has influence
across the boundary; comes into contact with the target system, organ, or cell;
and produces an outcome. For example, a dose in one tissue, such as the blood,
can serve as the exposure of another tissue that the blood perfuses.
SCIENTIFIC AND TECHNOLOGIC ADVANCES
Innovations in science and technology enable advances to be made in ex-
posure science. Numerous state-of-the-art methods and technologies measure
exposures, from external concentrations to personal exposures to internal expo-
sures. (Selected technologies considered in relation to the conceptual framework
3
Intensity is the preferred term because some stressors, such as temperature excesses,
cannot be easily measured as concentrations.
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Summary 7
are included in Figure S-2.) For example, developments in geographic informa-
tion science and technologies are leading to rapid adoption of new information
from satellites via remote sensing and providing immediate access to data on
potential environmental threats. Improved information on physical activity and
locations of humans and other species obtained with global positioning systems
and related geolocation technologies is increasingly combined with cellular-
telephone technologies. Biologic monitoring and sensing increasingly offer the
potential to assess internal exposures. In addition, models and information-
management tools are needed to manage the massive quantities of data that will
be generated and to interpret the complex interactions among receptors and en-
vironmental stressors. The convergence of those scientific methods and tech-
nologies raises the possibility that in the near future integrated sensing systems
will facilitate individual-level exposure assessments in large populations of hu-
mans or other species. The various technologies are discussed below.
Tracking Sources, Concentrations, and Receptors with
Geographic Information Technologies
Geographic information technologies--remote sensing, global positioning
and related locational technologies, and geographic information systems
(GIS)--are motivating an emphasis on spatial information in exposure science.
They can be used to characterize sources and concentrations and can improve
understanding of stressors and receptors when used in concert with other meth-
ods and data.
Remote sensing involves the capture, retrieval, analysis, and display of
information on subsurface, surface, and atmospheric conditions that is collected
by using satellite, aircraft, or other technologies. Remote sensing is an important
method for improving our capacity to assess human and ecologic exposures as it
provides global information on the earth's surface, water, and atmosphere, and it
can provide exposure estimates in regions where available ground observation
systems are sparse. For example, data collected with remote sensing over
"Ground Zero" was used initially to assess the potential asbestos hazards related
to the dust that settled over lower Manhattan after the collapse of the World
Trade Center towers. Remote sensing of vegetation combined with GIS has been
used to assess potential exposure of wildlife to pesticides and metals.
Global positioning system (GPS) and geolocation technologies--which
are now embedded into many cellular telephones, vehicle navigation systems,
and other instruments--provide a means of tracking the geographic position of a
person or other species. Geolocation technologies have been used extensively in
exposure-assessment studies, are important for providing accurate information
on the location of an individual or species in space and time, and offer precise
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8 Exposure Science in the 21st Century: A Vision and A Strategy
FIGURE S-2 Selected scientific and technologic advances for measuring and monitoring
considered in relation to the conceptual framework shown in Figure S-1.
exposure estimates. When geolocation data (with information on air or water
quality) are used with activity measurements readily available through portable
accelerometers, additional information can be inferred about potential uptake of
stressors.
GIS allows storage and integration of data from different sources (for
example, exposure information and health characteristics of populations) by
geographic location. It also provides quantitative information on the topologic
relationship between an exposure source and a receptor, which allows research-
ers to characterize proximity to roadways, factories, water bodies, and other land
uses. For example, GIS used with modeling data has provided information on
exposure exceedances of threatened and endangered species associated with
environmental contaminants. Web-based GIS increasingly serves as a tool for
educating and empowering communities to understand and manage environ-
mental exposures.
The increasing use of geographic information technologies (for example,
through cellular telephones, GPS, or Web-based systems), many of which are
operated by the private sector, raises important issues about privacy protection
and the use of the resulting data by exposure-science researchers for improving
public health.
Ubiquitous Sensing
Over the last 20 years, there have been substantial advances in personal
environmental-monitoring technologies. The advances have been made possible
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Summary 9
in part by cellular telephones, which are carried routinely by billions of people
throughout the world and may be equipped with motion, audio, visual, and loca-
tion sensors that can be manipulated with cellular or wireless networks. Pollu-
tion-monitoring devices can be integrated into the telephones (for example, for
measuring particulate matter and volatile organic chemicals). In this context,
cellular telephones, supporting software, and expanding networks (cellular and
WiFi) can be used to form "ubiquitous" sensing networks to collect personal
exposure information on millions of people and large ecosystems. People can
then act as "citizenscientists", collecting their own exposure data to inform
themselves about what they might be exposed to, and this can lead to more
comprehensive application of exposure-science tools for health and environ-
mental protection. However, validation of ubiquitous sensing networks to ensure
the accuracy and precision of the data collected is an important consideration.
Developing ubiquitous monitoring for personal exposure assessment will
depend on rapid advances in sensor technologies. Despite recent advances, per-
sonal sensors still have only modest capacity to obtain highly selective, multis-
tressor measurements. There is a need for a wearable sensor that is capable of
monitoring multiple analytes in real time. Such a device would allow more rapid
identification of "highly exposed" people to help to identify sources and means
of reducing exposures. Recent advances in nanoscience and in nanotechnology
offer an unprecedented opportunity to develop very small, integrated sensors
that can overcome current limitations.
With regard specifically to environmental exposure, advances in electronic
miniaturization of sensors and data management are motivating the development
of environmental sensor networks that can provide long-term real-time expo-
sure-monitoring data on our ecosystem. Much of the interest in network sensors
has been motivated by national-security concerns, including concerns about
monitoring drinking-water or air quality.
Biomonitoring for Assessing Internal Exposures
With advances in genomic techniques and informatics, exposure science is
moving from collection of external exposure information on a small number of
stressors, locations, times, and individuals to a more systematic assemblage of
internal exposures to multiple stressors in individuals in human populations and
multiple species in our environment.
The committee considered three broad topics in biomonitoring: measures
of internal exposure, biosignatures of exposure, and measurement of biochemi-
cal modifiers of internal exposure.
Measures of internal exposure to stressors are closer to the target site of
action for biologic effects than are external measures of exposure and so im-
prove the correlation of exposure with effects. Analytic methods enable the de-
tection of low concentrations of multiple stressors. The measurement of thou-
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10 Exposure Science in the 21st Century: A Vision and A Strategy
sands of small organic molecules in biologic samples with metabolomics is now
being applied to biomonitoring of chemicals in humans and in wildlife. Such
approaches are not limited to a chemical or class of chemicals selected in ad-
vance but rather provide broader, agnostic assessment that can identify expo-
sures and potentially improve surveillance and elucidate emerging stressors.
Proteomics and adductomics expand the types of internal measures of exposure
that can be analyzed, including the analysis of compounds in the blood that have
short half-lives, such as oxidants in cigarette smoke and acrylamide. Rapidly
evolving sensor platforms linked to physiologically based pharmacokinetic
(PBPK)4 models are expected to enable field measurements of chemical samples
in blood, urine, or saliva from human and nonhuman populations and rapid in-
terpretation of the concentrations in the samples. However, inferring the sources
and routes of these internal exposures remains a research challenge.
Biosignatures of exposure reflect the net biologic effect of internal ex-
posure to stressors that act on specific biologic pathways. For example, oxida-
tive modifications of DNA or protein can be used to represent the net internal
exposure to oxidants and antioxidants. Biosignatures provide better assessment
of exposuredisease correlations, but they are still limited in their ability to tar-
get reduction in any specific compound or source.
Measurement of biochemical modifiers of internal exposure can be
used qualitatively to identify populations that are expected to have greater inter-
nal exposures to a given stressor (for example, because of differences in metabo-
lism or higher absorption) or quantitatively by inclusion in PBPK
pharmacodynamic models used for exposure assessment and prediction of doses.
Transcriptomics, proteomics, and to a smaller extent metabolomics offer the
ability to measure the status of key biologic processes that affect the pharma-
cokinetics (that is the absorption, distribution, metabolism, or elimination) of
chemical stressors.
With regard to ecologic exposure assessment, the use of molecular tech-
niques as biomarkers to assess ecologic exposure to stressors is limited in that
most of these techniques cannot be linked quantitatively to the level of exposure
and are not highly selective. There is a need to develop rapid-response, quantita-
tive exposure-assessment tools that can provide useful information for exposure
assessment in ecologic risk assessments.
Models and Information-Management Tools
Models and information-management tools are critical for interpreting and
managing the quantities of data being generated with the expanding technolo-
gies. For example, satellite imaging and personal monitoring techniques are
4
A mathematical modeling technique for predicting the absorption, distribution,
metabolism, and excretion of a compound in humans or other animal species.
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Summary 11
generating enormous quantities of spatiotemporal data and information on peo-
ple's movements and activities, and biologic assays are capable of monitoring
millions of genetic variants, metabolites, or gene-expression or epigenetic
changes in thousands of subjects. The ability of models to provide a repository
for exposure information, to help in interpreting data and observations, and to
provide tools for predicting trends will continue to be a cornerstone of exposure
science.
Many types of models will continue to be important in exposure science--
for example, activity-based models for tracking the history of individuals or
populations and process-based models for tracking the movement of stressors
from source to receptor--but there is a growing need for structureactivity mod-
els that can classify chemicals with regard to exposure and potential health ef-
fects.
The key to the future of exposure models is how they incorporate the in-
creasing number of observations that are being collected. Although observations
alone are important, it is their analysis, through application of models, that elu-
cidates the value of the measurements. It is also important to quantify the uncer-
tainty in the exposure estimates provided by models. However, to fully address
environmental health concerns, exposure models need to be systematically inte-
grated into source to dose modeling systems.
Informatics encompasses tools for managing, exploring, and integrating
massive amounts of information from diverse sources and in widely different
formats. Informatics relies on model algorithms, databases and information sys-
tems, and Web technologies. Although it is highly developed in biology and
medicine, its application in exposure science is in its infancy; informatics offers
great promise for improving the linkages of exposure science to related envi-
ronmental-health fields.
A number of informatics efforts are under way. For example, ExpoCast
Database, developed as part of EPA's Expocast program to advance the charac-
terization of exposure to address the new toxicity-testing paradigm, is designed
to house measurements from human exposure studies and to support standard-
ized reporting of observational exposure information. Recently, a pilot Envi-
ronment-Wide Association Study was conducted in which exposurebiomarker
and disease-status data were systematically interpreted in a manner analogous to
that in a Genome-Wide Association Study.5 In addition, the exposure field has
developed and designed an exposure ontology6 to facilitate centralization and
integration of exposure data with data in other fields of environmental health,
including toxicology, epidemiology, and disease surveillance.
5
Genome-Wide Association Studies are epidemiologic studies that examine the
associations between particular genetic variants and specific disease outcomes.
6
Ontologies, specifications of the terms and their logical relationships used in a
particular field, are used to improve search capabilities and allow mapping of
relationships among different databases and informatics systems.
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12 Exposure Science in the 21st Century: A Vision and A Strategy
A VISION FOR EXPOSURE SCIENCE IN THE 21st CENTURY
New challenges and new scientific advances impel us to an expanded vi-
sion of exposure science. The vision is intended to move the field from its his-
torical origins--where it has typically addressed discrete exposures with a focus
on either external or internal environments and a focus on either effects of
sources or effects on biologic systems, one stressor at a time--to an integrated
approach that considers exposures from source to dose, on multiple levels of
integration (including time, space, and biologic scale), to multiple stressors, and
scaled from molecular systems to individuals, populations, and ecosystems.
The vision, the "eco-exposome", is defined as the extension of exposure
science from the point of contact between stressor and receptor inward into the
organism and outward to the general environment, including the ecosphere.
Adoption and validation of the eco-exposome concept should lead to the devel-
opment of a universal exposure-tracking framework that allows the creation of
an exposure narrative, the prediction of biologically relevant human and ecolo-
gic exposures, and the generation of improved exposure information for making
informed decisions on human and ecosystem health protection. The vision is
premised on the scientific developments of the last decade.
To advance this broader vision, exposure science needs to deliver knowl-
edge that is effective, timely, and relevant to current and future environmental-
health challenges. To do so, exposure science needs to continue to build capacity
to
Assess and mitigate exposures quickly in the face of emerging environ-
mental-health threats and natural and human-caused disasters. For example,
this requires expanding techniques for rapid measurement of single and multiple
stressors on diverse geographic, temporal, and biologic scales. That includes
developing more portable instruments and new techniques in biologic and envi-
ronmental monitoring to enable faster identification of chemical, biologic, and
physical stressors that are affecting humans or ecosystems.
Predict and anticipate human and ecologic exposures related to exist-
ing and emerging threats. Development of models or modeling systems will
enable us to anticipate exposures and characterize exposures that had not been
previously considered. For example, predictive tools will enable development of
exposure information on thousands of chemicals that are now in widespread use
and enable informed safety assessments of existing and new applications for
them. In addition, strategic use of such diverse information as structural proper-
ties of chemicals, nontargeted environmental surveillance, biomonitoring, and
modeling tools are needed for identification and quantification of relevant expo-
sures that may pose a threat to ecosystems or human health.
Customize solutions that are scaled to identified problems. As stated in
Science and Decisions: Advancing Risk Assessment (2009), the first step in a
risk assessment should involve defining the scope of the assessment in the con-
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Summary 13
text of the decision that needs to be made. Adaptive exposure assessments could
facilitate that approach by tailoring the level of detail to the problem that needs
to be addressed. Such an assessment may take various forms, including very
narrowly focused studies, assessments that evaluate exposures to multiple
stressors to facilitate cumulative risk assessment, or assessments that focus on
vulnerable or susceptible populations.
Engage stakeholders associated with the development, review, and use
of exposure-science information, including regulatory and health agencies and
groups that might be disproportionately affected by exposures--that is, engage
broader audiences in ways that contribute to problem formulation, monitoring
and data collection, access to data, and development of decision-making tools.
Ultimately, the scientific results derived from the research will empower indi-
viduals, communities, and agencies to prevent and reduce exposures and to ad-
dress environmental disparities.
For the committee's vision to be realized in light of resource constraints,
priorities need to be set among research and resource needs that focus on the
problems or issues that are critically important for addressing human and ecolo-
gic health. For example, screening-level exposure information may be adequate
to address some questions, targeted data may be useful for others, and extensive
data may be required in some circumstances. Health-protective default assump-
tions can provide incentives for data generation and can allow timely decisions
despite inevitable data gaps.
REALIZING THE VISION
The demand for exposure information, coupled with the development of
tools and approaches for collecting and analyzing such data, has created an op-
portunity to transform exposure science to advance human and ecosystem
health. The transformation will require an investment of resources and a sub-
stantial shift in how exposure-science research is conducted and its results im-
plemented. In the near term exposure science needs to develop strategies to ex-
pand exposure information rapidly to improve our understanding of where,
when, and how exposures occur and their health significance. Data generated
and collected should be used to evaluate and improve models for use in generat-
ing hypotheses and developing policies. New exposure infrastructure (for exam-
ple, sensor networks, environmental monitoring, activity tracking, and data stor-
age and distribution systems) will help to identify the largest knowledge gaps
and reveal where gathering more exposure information would contribute the
most to reducing uncertainty.
For example, more exposure data needs to be collected to populate emerg-
ing exposure databases (for example EPA's ExpoCast Database) and to develop
tools to systematically mine various sources of exposure information, so as to
bridge the gap between exposure science and other environmental-health disci-
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14 Exposure Science in the 21st Century: A Vision and A Strategy
plines. New and improved surveillance systems can be designed to increase our
knowledge of environmental stressors and provide information for estimation
and characterization of exposures. Targeted exposure studies will be essential
for gathering detailed information on hot spots or places of highest potential
impact to vulnerable and susceptible populations. Surveillance programs to-
gether with targeted exposure-measurement programs will help build a predic-
tive exposure network that can address environmental-health questions.
Research Needs
To implement its vision, the committee identified research needs that call
for further development of existing and emerging methods and approaches, vali-
dation of methods and their enhancement for application on different scales and
in broader circumstances, and improved linkages to research in other sectors of
the environmental-health sciences. The research needs are organized into several
broad categories addressed below, and they are organized by priority within
each category on the basis of the time that will be required for their development
and implementation: short term denotes less than 5 years, intermediate term 5-
10 years, and long term 10-20 years.
Providing effective responses to immediate or short-term public-health or
ecologic risks requires research on observational methods, data manage-
ment, and models:
Short term
Identify, improve, and test instruments that can provide real-time track-
ing of biologic, chemical, and physical stressors to monitor community and oc-
cupational exposures to multiple stressors during natural, accidental, or terrorist
events or during combat and acts of war.
Explore, evaluate, and promote the types of targeted population-based
exposure studies that can provide information needed to infer the time course of
internal and external exposures to high-priority chemicals.
Intermediate term
Develop informatics technologies (software and hardware) that can
transform exposure and environmental databases that address different levels of
integration (time scales, geographic scales, and population types) into formats
that can be easily and routinely linked with populationwide outcome databases
(for humans and ecosystems) and linked to source-to-dose modeling platforms
to facilitate rapid discovery of new hazards and to enhance preparedness and
timely response.
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Summary 15
Identify, test, and deploy extant remote sensing, personal monitoring
techniques, and source to dose model-integration tools that can quantify multiple
routes of exposure (inhalation, ingestion, and dermal uptake) and obtain results
that can, for example, be integrated with emerging methods (such as omics
technologies)7 for tracking internal exposures.
Long term
Enhance tracking of human exposures to pathogens on the basis of a
holistic ecosystem perspective from source through receptor.
Supporting research on health and ecologic effects that addresses past, cur-
rent, and emerging outcomes:
Short term
Coordinate research with human-health and ecologic-health scientists
to identify, collect, and evaluate data that capture internal and external markers
of exposure in a format that improves the analysis and modeling of exposure
response relationships and links to high-throughput toxicity testing.
Explore options for using data obtained on individuals and populations
through market-based and product-use research to improve exposure informa-
tion used in epidemiologic studies and in risk assessments.
Intermediate term
Develop methods for addressing data and model uncertainty and evalu-
ate model performance to achieve parsimony in describing and predicting the
complex pathways that link sources and stressors to outcomes.
Improve integration of information on human behavior and activities
for predicting, mitigating, and preventing adverse exposures.
Long term
Adapt hybrid designs for field studies to combine individual-level and
group-level measurements for single and multiple routes of exposure to provide
exposure data of greater resolution in space and time.
Addressing demands for exposure information among communities, gov-
ernments, and industries with research that is focused, solution-based, and
responsive to a broad array of audiences:
7
Technologies used to identify and quantify all members of particular cellular
constituents, for example, proteins (proteomics), metabolites (metabolomics), or lipids
(lipomics).
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16 Exposure Science in the 21st Century: A Vision and A Strategy
Short term
Develop methods to test consumer products and chemicals in premar-
keting controlled studies to identify stressors that have a high potential for expo-
sure combined with a potential for toxicity to humans or ecologic receptors.
Develop and evaluate cost-effective, standardized, non-targeted, and
ubiquitous methods for obtaining exposure information to assess trends, dispari-
ties among populations (human and ecologic), geographic hot spots, cumulative
exposures, and predictors of vulnerability.
Intermediate term
Apply adaptive environmental-management approaches to understand
the linkages between adverse exposures in humans and ecosystems better.
Implement strategies to engage communities, particularly vulnerable or
hot-spot communities, in a collaborative process to identify, evaluate, and miti-
gate exposures.
Long term
Expand research in ways to use exposure science to more effectively
regulate environmental risks in natural and human systems, including the built
environment.
Transagency Coordination
Exposure science is relevant to the mission of many federal agencies, and
transagency collaboration for exposure science in the 21st century would accel-
erate progress in and transform the field. Tox21--a collaboration among EPA,
the National Institutes of Health (NIH), and the Food and Drug Administra-
tion--that was established to leverage resources to advance the recommenda-
tions in the 2007 National Research Council report Toxicity Testing in the 21st
Century: A Vision and a Strategy serves as a relevant model. The present com-
mittee considers that the model used in establishing Tox21 could be extended to
exposure science and lead to the creation of Exposure21. Exposure21, in addi-
tion to engaging the stakeholders (government, industry, and nongovernment
organizations) involved in Tox21, would need to be extended to other federal
agencies--such as the U.S. Geological Survey, the Centers for Disease Control
and Prevention, the National Oceanic and Atmospheric Administration, the Na-
tional Science Foundation (NSF), and the National Aeronautics and Space Ad-
ministration--to promote greater access to and sharing of data and resources on
a broader scale. Including them would provide access to resources for transfor-
mative technology innovations, for example, in nanosensors.
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Summary 17
Enabling Resources
As the collaborative partnerships among agencies are expanded, there will
be opportunities to share research results, to demonstrate the value of exposure-
science research to other agencies and decision-makers, and to generate addi-
tional resources. The committee recommends that intramural and extramural
programs in EPA, NIEHS, the Department of Defense, and other agencies that
advance exposure-science research be supported as the value of the research and
the need for exposure information become more apparent.
Much of the human-based research in environmental-health sciences is
funded by NIH. However, none of the existing study sections that review grant
applications has substantial expertise in exposure science, and most study sec-
tions are organized around disease processes. In light of that and the role that an
understanding of environmental exposures can play in disease prevention, a re-
thinking of how NIH study sections are organized that incorporates a greater
focus on exposure science would allow a core group of experts to foster the ob-
jectives of exposure-science research. In addition, an increase in collaborations
between agencies should be explored; for example, collaborations between EPA,
NIEHS, and NSF could support integrative research between ecosystem and
human-health approaches in exposure science. However, many other agencies
engaged in exposure-science research could be included in the collaborations.
Because of the need to understand and prevent harmful exposures and
risks in our society, EPA and NIEHS need to be able to work with the academic
community to conduct exposure studies in all populations, particularly among
the most vulnerable (for example, the elderly, children, and the infirm), under
appropriate ethical guidelines.
The effective implementation of the committee's vision will depend on
development and cultivation of scientists, engineers, and technical experts with
experience in multiple fields to educate the next generation of exposure scien-
tists and to provide opportunities for members of other fields to cross-train in the
techniques and models used to analyze and collect exposure data. Exposure sci-
entists will need the skills to collaborate closely with other fields of expertise,
including engineers, epidemiologists, molecular and system biologists, clini-
cians, statisticians, and social scientists. To achieve that, the committee consid-
ers that the following are needed:
An increase in the number of academic predoctoral and postdoctoral
training programs in exposure science throughout the U.S. supported by training
grants. NIEHS currently funds one training grant in exposure science; additional
grants are needed.
Short-term training and certification programs in exposure science for
midcareer scientists in related fields.
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18 Exposure Science in the 21st Century: A Vision and A Strategy
Development, by federal agencies that support human and environ-
mental exposure science, of educational programs to improve public understand-
ing of exposure-assessment research, including ethical considerations involved
in the research. The programs would need to engage members of the general
public, specialists in research oversight, and specific communities that are dis-
proportionately exposed to environmental stressors.
Participatory and Community-Based Research Programs
To engage broader audiences, including the public, the committee sug-
gests the development of more user-friendly and less expensive monitoring
equipment to allow trained people in communities to collect and upload their
own data in partnership with researchers. Such partnerships would improve the
value of the data collected and make more data available for purposes of prior-
ity-setting and informing policy. One approach might include implementing a
system of ubiquitous sensors (for example, through the use of cellular tele-
phones, GPS, or other technologies) in two American cities to evaluate the fea-
sibility of such systems to develop community-based exposure data that are reli-
able. Potential issues of privacy protection would need to be considered.
CONCLUDING REMARKS
Exposure information is crucial for predicting, preventing, and reducing
human health and ecosystem risks. Exposure science has historically been lim-
ited by the availability of methods, technologies, and resources, but recent ad-
vances present an unprecedented opportunity to develop more rapid, cost-
effective, and relevant exposure assessments. Research supported by such fed-
eral agencies as EPA and NIEHS has provided valuable partnership opportuni-
ties for building capacity to develop the technologies, resources, and educational
structure that will be needed to achieve the committee's vision for exposure sci-
ence in the 21st century.
