Extramural Research
Presentation Abstract
Grantee Research Project Results
Robert Devlin
EPA National Health and Environmental Effects Research Laboratory,
Research Triangle Park, NC
Six years ago, there were several dozen epidemiology papers that reported
associations between daily changes in ambient PM concentration and increased
mortality and morbidity. However, very little was known about the underlying
pathophysiological processes which might explain how someone could inhale
a relatively small amount of particles and die within 24 hours. This presentation
summarizes progress made by the PM Centers and EPA scientists in providing
biological plausibility to the epidemiology studies through the identification
of mechanisms by which PM causes adverse health effects. These studies
have shown that PM can cause pulmonary inflammation and interfere with
oxygen exchange deep within the lung. PM has also been shown to adversely
affect the ability to fight off infections in the lung. Exposure to low
levels of PM has been associated with myocardial infarctions and alterations
in the autonomic nervous system control of the heart, potentially leading
to fatal arrhythmias. PM has also been shown to cause systemic inflammation
and to increase the likelihood of blood clot formation and atherosclerotic
plaque progression. These studies provide co herence to the epidemiology
studies and extended their observations, thus strengthening the science
in sup-port of the PM standard. Although substantial progress has been
made in this area of research, there are still significant areas of uncertainty.
Future challenges include a better understanding of: (1) the cellular
and mo-lecular mechanisms which underlie the pathophysiological changes
caused by PM; (2) whether different PM components or PM derived from different
sources operates through different mechanisms; and (3) whether PM causes
injury to different susceptible populations by different mechanisms.