Prof. Ralph Delfino
- Research Area:
Associate Professor and Vice Chair for Research and Graduate Studies, Department of Epidemiology, School of Medicine at UC Irvine.
MD degree from University of Chicago; Ph.D. in epidemiology from McGill University, Montreal.
Professor Delfino brings expertise on the analysis of impacts of air pollution on human populations. His focus is in environmental epidemiology, particularly on the relationships between well characterized air pollution exposures and respiratory and cardiovascular outcomes in susceptible populations. This work has been funded by the National Institutes of Health, National Institute of Environmental Health Sciences (NIEHS), US Environmental Protection Agency, California Air Resources Board, and the South Coast Air Quality Management District.
His epidemiologic studies evaluate multiple clinical, biological and genetic factors to understand the effects of air pollutants on respiratory health, cardiovascular function, oxidative stress, and pulmonary and systemic inflammation. This is being accomplished with longitudinal studies in human subjects involving repeated measures of exposures and outcomes to obtain precise estimates of exposure-response relationships. Each subject serves as his or her own control. This has involved following cohorts of asthmatics (panels) with daily repeated measures for several months using spirometers, exhaled NO as a marker of airway inflammation, and electronic diaries and data loggers to measure medication use, spatial location, physical activity, and asthma symptoms.
Similarly, for cardiovascular panels this has involved ambulatory Holter ECG and hourly blood pressure data, exhaled NO, and repeated blood draws for circulating biomarkers of inflammation, thrombosis, oxidative stress, and antioxidant capacity. This research includes an evaluation of the effects of air pollutant exposures on leukocyte gene expression in several key biological pathways including NF-kB activation, cytokine and chemokine-mediated signaling, coagulation, Nrf2/ARE-mediated oxidative stress response, and xenobiotic metabolism. He is also evaluating whether polymorphisms in genes involved in oxidative stress responses modify associations between repeated measures of air pollutants and health outcomes.
The panel studies involve detailed exposure assessments with personal air monitoring systems that subjects carry with them during their daily activities, and indoor and outdoor home air monitors. The main goal is to understand the chemical composition, size factions and properties of particles that lead to observed health effects, and to trace these characteristics back to their sources. Chemical assays (some in real time) and in vitro assays of the redox and electrophilic activity of particles are among the methods being used.
Dr Delfino is also interested in the health impact of mobile pollutant sources such as freeways and in-vehicle exposure that are of growing concern. Ongoing work has focused on acute effects using panel study data. Other work involves evaluating the risk of repeated hospitalization for asthma from exposure to local traffic near the subject’s home. Future work is planned to look at disease development such as pediatric asthma onset using a cohort design combined with a nested panel in subjects who have developed the disease or intermediate endpoints. Overall, his findings are generating new data on susceptibility to the adverse effects of air pollutants and the role that toxic pollutants in urban air play in respiratory and cardiovascular health.
- Environmental epidemiology
- Air pollution health effects
- Chronic disease epidemiology
- Gene-environment interactions