www.epa.gov/ord
HUMAN HEALTH RESEARCH PROGRAM
Research Progress to
Benefit PUBLIC HEALTH
U.S. Environmental Protection Agency
Office of Research and Development
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&ERA
HUMAN HEALTH RESEARCH PROGRAM
Protecting the public from environmental health
threats is integral to the mission of the U.S. Environmental
Protection Agency. Researchers in EPA's Office of Research
and Development (ORD) are supplying the science
to improve the ability to assess public health risks from
environmental pollutants.
Solving Environmental Problems with Research
EPA's Human Health Research Program uniquely integrates many
environmental science disciplines to build a strong foundation for risk
assessment and improve understanding of toxic chemical exposure
and health effects. The program involves coordination of fundamental
research to fill gaps in scientific knowledge to improve assessment
of public health risks and solve environmental problems.
Human health researchers are working together to answer vital public
health questions to solve environmental problems. By understanding
how pollutants affect our lives, we are able to make knowledgeable
decisions to protect the public health.
Our research program is evaluated through extensive independent
expert review by EPA's Board of Scientific Counselors. This evalua-
tion assesses the development and application of new human health
research knowledge, as well as the relevance, quality, and scientific
leadership of the program.
Improving Risk Assessment
The science of assessing risk involves evaluating all that is known -
and unknown - about a toxic chemical. When scientific uncertainties
exist, assumptions or simplified approaches are used to fill the gaps
in knowledge. EPA researchers and their colleagues are advancing
environmental science to add to our knowledge base and improve the
quality of risk assessments.
Science that explains how laboratory findings can be applied to
humans is critical to advancing risk assessments and enables EPA
to adequately protect the public. Issues under study to improve risk
assessment include understanding:
• The relationship between health effects
from high-dose exposures in animals to low
doses in the environment
• The difference between a single exposure
to a toxic chemical and exposure over a lifetime
• The difference between exposures from
a single chemical to mixtures of chemicals
Why are certain populations more sensitive to pollutants
than others? What biological processes occur upon exposure
to toxic chemicals? How does exposure affect our health?
U.S. Environmental Protection Agency
Office of Research and Development
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Research
Contributions
EPA's Human Health Research Program has
led to a more systematic understanding of the physical,
chemical, and biological processes that underlie how
humans can be affected by environmental pollutants.
ASSESSING RISKS OF DIOXINS AND RELATED CHEMICALS:
Dioxins in the environment can result in a wide range of adverse
health effects. Many studies have shown dioxins and related
chemicals can lead to interruption of a receptor in the body called
the aryl hydrocarbon (Ah) receptor, potentially affecting cell growth,
form, and function. EPA research has been instrumental in demon-
strating that this biological interference occurs at very low doses
across a range of species, including humans. This research has
helped EPA and international health organizations improve their
risk assessments of dioxins and related compounds.
DETERMINING RISKS OF CUMULATIVE EXPOSURES TO PESTICIDES:
Concerns have been raised about whether widely used pesticides
result in cumulative risks to consumers through the food in their
diets. EPA is required under the Food Quality Protection Act to
regularly re-evaluate human tolerances for pesticides in current
use and consider the health impacts from exposure to multiple
pesticides. Ongoing research has led to improved cumulative
assessment of pesticides which serves to protect the public health.
This research has enabled local governments, grower associations,
and produce shippers to reduce the risks of exposure to multiple
pesticides. Studying cumulative risks has been extended to drinking
water contaminants as a result of these successes.
UNDERSTANDING ENVIRONMENTAL IMPACTS ON ASTHMA:
Asthma is a serious and growing health problem affecting more than
20 million Americans. EPA research is focusing on environmental
issues that may cause or exacerbate asthma, with particular atten-
tion paid to mold and air pollutants such as particulate matter, ozone,
and diesel emissions. For example, researchers have discovered a
biomarker that can predict the severity of an asthmatic response in
susceptible people, resulting in new protocols for improving indoor air
quality, and providing the scientific basis for public education policies
and risk management strategies involving exposure to molds.
ASSESSING POPULATION EXPOSURES TO POLLUTANTS: Accurately
determining total human exposures to environmental pollutants within
a community is critical for EPA to assess and manage human health
risks. To this end, EPA has developed a model of how populations
are exposed to airborne toxins. The model, called the Stochastic
Human Exposure and Dose Simulation Model or SHEDS, estimates
an individual's exposure to benzene, a known air toxin, while indoors,
outside, and in vehicles. It also provides independent estimates
of population exposures that allow EPA and state governments to
improve assessments of mobile source and urban air toxics exposure.
This research has led to improved risk assessment and management
through more realistic exposure assessment methods.
PROTECTING SUSCEPTIBLE POPULATIONS: Exposure to environ-
mental pollutants can have a greater impact on the very young
and adults over age 65. EPA's human health research program has
improved understanding of how and why these groups are more
vulnerable to some pollutants. Research has supported the applica-
tion of safety estimates in risk assessments to protect children from
high-use pesticides such as chlorpyrifos. Scientists have conducted
research that identifies wide population variability in a gene that
produces enzymes for detoxifying organophosphate pesticides.
These findings show that some people, especially young children,
are more sensitive to the adverse health effects of these pesti-
cides. Researchers also are supporting Native American Tribes by
conducting the science to determine potential risks unique to their
populations because of their customs, occupations and lifestyles.
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FOR MORE INFORMATION
visit www.epa.gov/hhrp
EPA's Human Health Research Program has led to a more
systematic understanding of the processes that underlie
how humans can be affected by environmental pollutants.
Future Directions
EPA's Human Health Research Program is strategically aimed
at providing the methods, tools, and data needed to improve risk
assessments to protect public health. The primary goal of the
program is to reduce reliance on default assumptions and simplified
approaches used in risk assessments in the absence of conclusive
data. Research will be conducted in areas where there are the
greatest uncertainties in the science and where the science can
address the real-world needs of the Agency. Four main research
areas are:
• BIOLOGICAL (MECHANISTIC) RESEARCH: Understand
underlying biological processes triggered when people
are exposed to environmental contaminants.
•SUSCEPTIBLE SUBPOPULATION RESEARCH: Protect the
aging population, children, and those with chronic diseases
by providing new insights into how pollutants may affect
their health.
• CUMULATIVE RISK RESEARCH: Provide clues to what
happens when we are exposed to the many chemical
mixtures in our environment.
• TOOLS FOR EVALUATING RISK MANAGEMENT DECISIONS:
Develop measurement tools and biological indicators to
assess the impact of regulatory decisions on public health.
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EPA's human
health researchers
are answering
vital public
health questions
and solving
environmental
problems.
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www.epa.gov/ord
HUMAN HEALTH RESEARCH PROGRAM
www.epa.gov/hhrp
FOR MORE INFORMATION, CONTACT:
Hugh A. Tilson
Director, Human Health Research Program
919-541-4607 • tilson.hugh@epa.gov
U.S. Environmental Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
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