You are here:
THE ROLE OF ORGANIC COMPOUNDS IN PARTICULATE MATTER (PM)-INDUCED TOXICITY
Impact/Purpose:
This work will support efforts to (1) Identify toxic source based components to be assessed for dose response studies; (2) address the interest of EPA's OTAQ in examining human toxicity from newer diesel engine exhaust (PM and gas phase components).
Description:
We have tested the hypothesis that organic and ozonized organic components of particulate matter (PM) may play a role in the induction of lung toxicity reported in some epidemiological studies. Our lab has utilized diesel exhaust particles (DEP) and extracts of diesel exhaust (i.e., PM plus some gas phase constituents collected in impingers in collaboration with NRMRL investigators; termed ExDE) as an important source of PM that is relatively rich in organic constituents. In work with the ExDE, we have shown than ExDE collected from an engine under heavy load is more bioactive in human airway epithelial cultures than ExDE at low load. Exposure of diesel PM to ozone (at 0.1 ppm) increases the potency of the DEP in the rat model. It is likely that the organic component of the parent and ozonized DEP is responsible for the observed lung responses using ozone-exposed carbon black (relatively poor in organic content). The mechanisms related to this increased potency observed in our studies using a mixture of PM and a gaseous co-pollutant remain to be fully elucidated. Future research is aimed at determining the bioactive components of ExDE, DEP, and ozonized DEP and their mechanisms of action; and examining the responses of potentially susceptible subpopulations (e.g., asthmatics) in vitro to diesel exhaust.