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About Human Health Research at the Environmental Protection Agency
The U.S. Environmental Protection Agency (EPA) was established in 1970 in response to growing concerns over polluted air, unclean rivers, unsafe drinking water, endangered species, and careless waste disposal. EPA was given the responsibility for implementing a broad set of federal environmental laws, which have contributed in the intervening years to significant improvements in environmental quality. Currently, EPA has jurisdiction over more than a dozen statutes enacted to protect public health and the environment (e.g., the Safe Drinking Water Act, the Food Quality Protection Act, and the Clean Air Act).
EPA is both a regulatory and a scientific agency; it is one of only a few federal organizations that operates in this capacity. The environmental laws that form the legal basis for EPA's regulatory activities also authorize its research efforts (e.g., the Food Quality Protection Act, Amendments to the Safe Drinking Water Act). It is this research that provides the foundation for scientifically defensible environmental policies, programs, and regulations. EPA research is housed chiefly in the Office of Research and Development (ORD).
EPA's Mission
Protect human health and safeguard the natural environment - air, water, land - upon which life depends.
EPA's Office of Research and Development (ORD)
ORD is the principal research arm of EPA. Its role is to provide the critical science for environmental decision-making. Unlike much of EPA, ORD has no direct regulatory function- its responsibility is to inform the regulatory process. Through the development of technical information and scientific tools, ORD's research strengthens EPA's science base, providing its Program Offices and Regional Offices with sound scientific advice and information for use in developing and implementing tenable environmental policies, regulations, and practices. ORD now is comprised of 7 national Laboratories and Centers across the country and addresses issues related to the environment and human health.
Human health research at ORD addresses needs arising from the Risk Assessment and Risk Management Paradigm (Figure 1). Human health risk assessment involves a qualitative and quantitative characterization of the relationship between environmental exposures and effects observed in exposed individuals and populations. The National Research Council (1983) has described four primary steps in the process of risk assessment, i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization. Risk assessment is the primary scientific input to the risk management process, which involves the recognition of a potential new risk and development, selection, and implementation of EPA actions to address the risk. Risk management often considers a wide variety of other factors. The overall process of risk assessment and risk management is often referred to as the Risk Assessment-Risk Management Paradigm.
ORD has historically aligned its organizational structure to be consistent with the Risk Assessment/Risk Management Paradigm. For example, the National Exposure Research Laboratory (NERL) focuses on measuring exposures and producing scientifically defensible exposure models that reduce the gaps in scientific knowledge related to actual human exposure to pollutants. In the Risk Assessment-Risk Management paradigm, dose-response assessment is the process for determining the likelihood of an adverse effect at a particular exposure or dose. A primary concern for dose-response assessment is an understanding of the dose of the environmental stressor that reaches its target organ, tissue, cell, or biomolecule. Research on issues related to dose is largely conducted at NERL and the National Health and Environmental Effects Research Laboratory (NHEERL). Research at NERL focuses on pharmacokinetic (PK) modeling to estimate internal dose metrics for multi-route aggregate exposure. Research at NHEERL focuses on determining the basis for improving inter- and intra-species extrapolations in risk assessment and determining the biologically effective dose of the parent compound or metabolite(s) of the pollutant.
The goal of hazard identification is to describe and ultimately predict in humans the toxicological effects of environmental stressors that might occur due to exposure to environmental agents. Research related to hazard identification is largely conducted at NHEERL and focuses on test methods development and characterization of hazard potential in animal models. Clinical or epidemiological studies may also used to identify potential risks in the human population and generate testable hypothesis for future studies in animal or in vitro models. Risk assessment is often confounded by a number of uncertainties related to the risk assessment methodology, including extrapolation across species, extrapolation from short-term to lifetime exposures, and variability of response within the human population. A significant component of research at NHEERL focuses on reducing or eliminating those uncertainties. Research at NHEERL also seeks to understand the cascade of events between the presence of an environmental stressor at a target site and the ultimate manifestation of toxicity, i.e., the toxicity pathway. Knowledge of the sequence of biological events that must occur to produce an adverse effect ( i.e., the mechanism of action, or an understanding of some, but not all, of the key biological steps leading to toxicity, i.e., the mode of action) is being used with increasing frequency in risk assessment. The National Risk Management Research Laboratory (NRMRL) focuses on providing the most effective and useful risk management options and increasing better linkages between risk assessment and risk management efforts.
Intramural research conducted by NERL, NHEERL, and NRMRL is complemented by extramural research sponsored by ORD's National Center for Environmental Research (NCER). The Science to Achieve Results (STAR) program, which is administered by NCER, is the major extramural funding program within ORD. The STAR Program annually issues a series of competitive solicitations for
proposals from the scientific community to conduct research in areas of science important to EPA's mission. These solicitations are developed with significant cross-agency and interagency involvement in their planning, writing, and review and are often funded jointly with other Federal agencies such as the National Institute of Environmental Health Sciences (NIEHS). Proposals submitted to the STAR Program are subjected to both external review by non-competing scientists from outside of EPA and internal relevancy review conducted by scientists and managers from ORD and EPA's regulatory and regional offices. This review process ensures that only high quality projects of highest priority to EPA are supported through the STAR Program. The STAR Program communicates its research results to other scientists in ORD and EPA's program and regional offices and the public through websites, meetings, and publications. Examples of STAR research include 12 EPA/NIEHS-supported Centers for Children's Health and Disease Prevention.
Clients for human health research are risk assessors at the Agency's Program and Regional Offices, ORD's National Center for Environmental Assessment (NCEA), the states, other Federal agencies, international health organizations, the regulated community, and the academic community. The stakeholders use the outputs from the Human Health Research Program to characterize and extrapolation risk from exposure-dose-response relationships, single-to-multiple chemical pathways, and laboratory animals to humans. Progress is measured by the extent to which the program's methods, models and data are actually used in peer-reviewed risk assessments.
Core and Problem Driven Research
Because EPA is a regulatory agency, it is recognized that research must be results-oriented and customer- focused. Some research is required by law, while other research is initiated in response to specific environmental exigencies or opportunities. In the report Building a Foundation for Sound Environmental Decisions, however, the National Research Council (1997) recommended that EPA maintain a balanced program of Core and Problem-Driven research.
Core research seeks to produce a fundamental understanding of the key biological, chemical, and physical processes that underlie environmental systems, thus forging basic scientific capabilities that can be applied to a wide range of environmental problems. Core research addresses questions common to many EPA programs and they provide the methods and models needed to confront unforeseen environmental problems.
Human Health Research Program is a Core Research Program
Adapted from Committee on Research Opportunities and Priorities for EPA,
Building a Foundation for Sound Environmental Decisions, NRC, 1997
Much of the Human Health Research Program can be categorized as core research since much of it focuses on multi-disciplinary cross-cutting issues such as susceptibility and extrapolation. Problem-driven research, on the other hand, focuses on regulatory or program activities, such as court-ordered deadlines. Problem-driven human health issues associated with specific pollutants (e.g., particulate matter, drinking water contaminants, air toxics, endocrine disruptors, pesticides and toxic substances) are addressed in separate ORD Research Strategies and Multi-Year Plans. The relative emphasis on research themes may change as ORD priorities shift, as new data surfaces, as court-ordered deadlines are met, or as budgets fluctuate. Substantial efforts are made by ORD, however, to build and maintain a research program that is both relevant to the scientific problem and responsive to EPA's needs.
As seen in the Figure, core and problem-driven research are not mutually exclusive. In fact, they are highly complementary and interactive, each informing the other. Fundamental research issues that cut across several areas must often be addressed before more problem-driven questions can be studied. There is a constant need to integrate problem-driven and core research. For example, the Food Quality Protection Act of 1996 specifies that the EPA shall consider the risk associated with cumulative exposures of chemicals based on their mode of action. In order to develop predictive models of chemical interaction, fundamental research has to be done to identify the biological mode or mechanism of action to be used in the cumulative risk assessment. A component of ORD's Human Health Research Program focuses on developing mechanistic information on major classes of environmental stressors which can be used to develop predictive models for risk assessment. Another example of the need to link core and problem-driven research is that risk assessors are required to account for the unique susceptibilities of sensitive subpopulations in the risk assessment process. In this regard, part of ORD's Human Health Research Program focuses on identifying potential populations at risk and determining the extent to which their differential response to pollutants could influence the risk assessment process. The blend of core and problem-driven research yields a robust research portfolio that couples a stable core effort with research needs derived from the regulatory mission of the EPA.