Efficacy of screens in removing long fibers from an aerosol stream--sample preparation technique for toxicology studies.

Fiber dimension (especially length) and biopersistence are thought to be important variables in determining the pathogenicity of asbestos and other elongate mineral particles. In order to prepare samples of fibers for toxicology studies, it is necessary to develop and evaluate methods for separating fibers by length in the micrometer size range. In this study, we have filtered an aerosol of fibers through nylon screens to investigate whether such screens can efficiently remove the long fibers (L >20 µm, a typical macrophage size) from the aerosol stream.

Dustiness of fine and nanoscale powders.

Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber.

Comparison of air sampling methods for aerosolized spores of B. anthracis Sterne.

Bacillus anthracis Sterne spores were aerosolized within a chamber at concentrations ranging from 1 x 10³ to 1.7 x 10⁴ spores per cubic meter of air (particles (p)/m³) to compare three different sampling methods: Andersen samplers, gelatin filters, and polytetrafluoroethylene (PTFE) membrane filters. Three samples of each type were collected during each of 19 chamber runs.

Recovery efficiency and limit of detection of aerosolized Bacillus anthracis Sterne from environmental surface samples.

After the 2001 anthrax incidents, surface sampling techniques for biological agents were found to be inadequately validated, especially at low surface loadings. We aerosolized Bacillus anthracis Sterne spores within a chamber to achieve very low surface loading (ca. 3, 30, and 200 CFU per 100 cm(2)).

Aerosolization of single-walled carbon nanotubes for an inhalation study.

Single-walled carbon nanotubes (SWCNT) are being produced in increasing quantities because of high interest in applications resulting from their unique properties. Because of potential respiratory exposures during production and handling, inhalation studies are needed to determine potential toxicity. A generation system was designed to produce respirable aerosol at 5 mg/m(3) for a 1-wk animal (mouse) exposure.

In vitro cytotoxicity of Manville Code 100 glass fibers: effect of fiber length on human alveolar macrophages.

Background: Synthetic vitreous fibers (SVFs) are inorganic noncrystalline materials widely used in residential and industrial settings for insulation, filtration, and reinforcement purposes. SVFs conventionally include three major categories: fibrous glass, rock/slag/stone (mineral) wool, and ceramic fibers. Previous in vitro studies from our laboratory demonstrated length-dependent cytotoxic effects of glass fibers on rat alveolar macrophages which were possibly associated with incomplete phagocytosis of fibers >or= 17 microm in length.