Research Program Area: Health & Exposure
Detailed studies have been conducted of the stack-collected fine particles collected at a representative oil-burning power plant in Southern California. Samples were collected over a three-week period with a two-stage particle sampler designed to aerodynamically classify the particles and collect them into coarse and fine fractions, respectively. This separation was achieved with a cyclone separator with cut size of about 5 µm aerodynamic diameter. Thus, the principal respirable particles are in the fine fraction. Detailed studies were conducted of the physical and chemical characteristics of the collected particles showing the coarse particles to consist of some pitted cinder-like particles, some iron rust-like particles, and metallic sulfates. The fine particles consisted primarily of metallic sulfates and were 85% soluble in water (suggesting considerable solubility in body fluids), with an important fraction being associated with the biologically active nickel and vanadium sulfates. Biological studies of the mutagenesis of these oil fly ash particles showed that there was some slight mutagenic activity indicated (as assessed in Ames bacterial mutagenesis assays), and also there was considerable cellular toxicity demonstrated by in vitro exposure of rabbit pulmonary alveolar macrophages to these fly ash particles at different concentrations. The cytotoxicity results are consistent with the known cellular toxicity associated with soluble forms of vanadium as present in oil ash. The mutagenesis results indicate further studies are needed for more complete evaluation.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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