Remediation of Superfund sites can release nanoscale particles into the environment, along with hazardous vapors. The health effects of these complex mixtures and materials, especially emerging materials produced by the nanotechnology industry, are not sufficiently well understood. It has been hypothesized that the adverse health effects due to exposure to environmental particles (e.g., airborne particulate matter) is, at least in part, due to generation of reactive oxygen species (ROS), but more data are needed to test this mechanism. This project focuses on 3 main areas: (I) using a laboratory combustion system to create complex mixtures of toxic by-products emitted from thermal processing of materials that contain brominated flame retardants; (II) characterizing the generation of reactive oxygen species from nanoscale materials in the environment; and (III) making use of nanotechnology to answer questions that have arisen in earlier studies of nanoparticle toxicity. In the first aim, this project will construct a small, laboratory-scale system to simulate the thermal processing of materials containing brominated flame retardants; the gaseous and particulate by-products of this process will be examined by other projects in this proposal using bioassays for polybrominated diphenyl ethers (PBDEs) and brominated dioxins and furans. In the second aim we will quantitatively measure two of the most important ROS - hydroxyl radical (OH) and hydrogen peroxide (H{2}O{2}) - formed by nanoparticles in a cell-free surrogate lung fluid and, later, in cell cultures. We will also examine how simulated atmospheric reactions alter the ability of nanoparticles to form ROS. In the third aim of this project we will synthesize a range of novel, multi-functional nanoparticles in order to study several questions related to nanomaterial toxicity, in part in conjunction with other projects in the UC Davis Superfund Program.