Extramural Research
Research Centers
Grantee Research Project Results
John R. Froines, Director
University of California, Los Angeles, CA
EPA Grant Number: R827352
2003
Progress Report
Center
sub-projects
Center Overview:
With over 10 million cars and trucks on the road each day, the Los Angeles Basin is the perfect setting for the Southern California Particle Center and Supersite (SCPCS) which has been exploring health and exposure issues related to mobile source pollution. Over the past 5 years the SCPCS has taken advantage of the unique features of the area and made important contributions to the question of how airborne particulate matter (PM) affects health and what sources are important. By bringing together researchers from the major universities in Southern California, the SCPCS uses a multidisciplinary approach to air pollution research.
Studies of PM Sources, including Atmospheric Chemistry, and Related Particle Characteristics: Research in the basin has been geared towards exploring the differences in particles as they relate to sources. One element of this exploration includes looking at particles at the “source” of emission and also at a “receptor” site, after they have traveled across the basin and undergone atmospheric chemistry. Atmospheric chemistry is an important source of toxic PM components. Data shows that as you move across the basin from west to east, certain PAHs become more prevalent and the size modes shift from a predominance of PAHs in the ultrafine mode at the source, to PAHs in the accumulation mode at the receptor site.
Freeway Studies—Relevance of Mobile Sources for Toxicology and Health: Studies conducted directly adjacent to the freeway demonstrate large numbers of ultrafine particles are generated from fossil fuel combustion which has significant health implications. Research has established that in addition to respiratory effects of PM, neurological, cardiovascular, and developmental endpoints are of concern. Studies have been conducted in mice, rat and human populations to explore the effects of freeway exposures to health endpoints. Cardiovascular effects studies, done in both aged rats and healthy humans, showed changes in heart rate variability and blood pressure. Allergic mice have been used to explore airway responses at varying distances from freeways. Inflammatory and immunological responses were evident at close proximity to the freeway. The Children’s Health Study, working in conjunction with the SCPCS, showed that children living by a free-way were more likely to develop asthma and chronic deficits in lung growth were of clinical significance. Developmental studies indicated low birth weights and pre-term births in offspring exposed to diesel vehicle emissions and inflammatory central nervous system responses were noted in a mouse model in close proximity to a freeway.
PM Toxicity Studies in Relation to Biological/Chemical Hypotheses: Our understanding of how PM affects health has improved considerably during the last five years of PM Center research. Chemical components of PM capable of causing oxidative stress are particularly important. The hypothesis proposes organic chemicals and metal constituents of PM generate highly oxygen species (ROS) which produce inflammation that can lead to inflammatory effects and cell death. It has also been shown that ultrafine particles, on a per mass basis, have the greatest potency towards oxidative stress. We have demonstrated that ultrafine particles are taken up by cells and preferentially located in the mitochondria disrupting the organelle’s function and causing cell death.