This task applied integrated earth and health science characterization methods to examine how the mineralogical and geochemical properties of earth materials from diverse sources may influence their potential toxicity. An important focus was on asbestiform minerals, acicular crystals, and acicular cleavage fragments of silicate minerals. However, other earth materials were also studied such as mine wastes, mineral processing wastes, a variety of soils, dusts from dry lake beds, volcanic ash, coal fly ash, coal dust, and wildfire ash. This work was carried out in close cooperation with toxicologists, epidemiologists, and molecular biologists. The ultimate goal of this task was to provide mineralogical and geochemical insights into the mechanisms by which minerals may trigger disease.
Task activities focused on several areas:
Development of geochemical leach methods that measure the solubility and reactivity of specific earth material constituents (such as asbestos fibers, acicular cleavage fragments, cement dusts, etc.) in simulated human lung and gastrointestinal fluids.
Application of chemical reaction path modeling to interpret the results of the geochemical leach test methods, and to model general mineral-fluid reactions in the body.
Comparison of the compositions, mineralogical properties, geochemical reactivities, and toxicological effects of earth materials from diverse sources.
Provide external collaborators with samples of well-characterized earth materials, of which they will measure the toxicological effects using a variety of in vitro toxicity tests. Our ongoing studies have utilized lung epithelial cell lines to model effects of inhalation exposure, but we are investigating other types of in vitro tests that might be used to simulate toxicity via other exposure pathways such as ingestion.
Pursue longer-term collaborative studies with toxicologists to provide them with well-characterized earth materials for use in in vivo inhalation or ingestion toxicity and uptake tests. Such in vivo tests are generally thought to provide clearer indications of the potential toxicity of substances than in vitro toxicity tests, but are not as commonly used due to their high costs.
Pursue collaborative studies with health scientists who are doing biomonitoring and exposure assessment studies. USGS would provide characterization studies of the materials to which humans were exposed, which could be used to help interpret the results of ongoing biomonitoring studies.