The two primary aims of the Exposure Assessment Research Core are to carry out research on the best methods and approaches for assessment of exposure to environmental agents of interest. Core members seek to improve exposure assessment for risk assessment and to assist definition of dose-response in epidemiologic investigation. Student training in techniques and methods of exposure assessment is also a research-related objective, as is assisting communities in understanding exposure to environmental agents.

Shortly after the NIEHS Center began in April 1996, Dr. John Froines, Dr. William Hinds and Mr. Ed Avol organized the "Southern California Exposure Assessment Group." Their objective was to maximize the effectiveness of the EARC. The Group was comprised of faculty from UCLA, USC, UCR, UCI, and Cal Tech in addition to independent scientists from the professional community with research interest in exposure assessment. Southern California has many outstanding, internationally recognized scientists in environmental exposure assessment, and our Center provided a unifying structure to bring these investigators together to identify ways to improve exposure assessment and to develop new collaborative research on important environmental problems.

The Exposure Assessment Group was a direct result of the existence of this Center and brought together approximately 30 faculty to meet for dinner discussions every other month.

The group established the following objectives:

• To improve and expand interaction between epidemiologists concerned with health outcomes and scientists whose primary focus is exposure assessment,
• To provide more current information about ongoing exposure assessment research in Southern California,
• To develop new, collaborative research between investigators in epidemiology, dosimetry, toxicology and exposure assessment,
• To better define the nature and scope of regional environmental problems,
• To identify new funding sources for research on problems relevant to the region.

It was apparent at the outset that this Group should include epidemiologists, toxicologists, and biostatisticians from the NIEHS Center to facilitate interaction across disciplines. The group evolved from one made up primarily of persons with exposure interests to a broader group that discussed issues on an interdisciplinary basis.

The formation of the Exposure Assessment Group was also intended to provide a basis for interaction between State-funded programs such as the Toxic Substances Research and Teaching Program (TSR&TP), the Center for Occupational and Environmental Health (COEH) at UCLA, and the federally funded Environmental Health Sciences Center.

Examples of discussion areas for the Exposure Assessment Group included:

• Characterization of the ambient environment including long-term exposures, inside versus outside exposure, time-activity-behavioral factors in exposure assessment, and other methodologic issues,
• Are particles killing people? What is in a particle?
• How best to model exposures,
• PM2.5 versus PM10,
• Biogenic particles/bioaerosols,
• 1,3-Butadiene: Atmospheric chemistry and exposure characterization,
• MTBE-health effects, exposure characterization and related matters,
• Air toxics in California,
• Diesel exhaust issues.

In early 1998, the Group pursued funding from the California Air Resources Board (ARB) to build a mobile particle concentrator for conducting toxicologic and human clinical research on airborne particulate matter (PM). Funding was sought from U.S. EPA as part of the STAR Program to establish a Center for Airborne Particulate Matter in Southern California, as well as to seek funding to establish an EPA intensive air monitoring site (a Supersite) in the same region. Dr. Froines served as Principal Investigator for the three applications.

Overall, these research funds provide a basis to establish a major PM research center in southern California to address the 10 research priorities of the National Research Council (NRC) for PM. These new activities derive directly from the existence of the Center, and faculty from the two Centers overlap significantly. All of the members of the EARC are participating faculty in the PM Center, and all research is collaborative.

The objective of the Supersite and the PM Center is to bring together outstanding scientists from leading universities in Southern California to identify and conduct the highest priority research for PM to ensure protection of the public health. The PM Center produces a framework for the integration of research disciplines to investigate PM through a multidisciplinary approach including exposure assessment, toxicology and epidemiology and enhances the excellent collaboration which exists among the Center investigators in these disciplines.