Trace metals are reported to play important roles in catalyzing the formation of highly reactive oxygen species (ROS), which are implicated in enhanced disease development. Whether trace metals from a concrete cutting saw increase the toxicity of silica is unclear. In this study, pure metal plates of aluminum (Al), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), nickel (Ni), tin (Sn), and tungsten (W), all used in making saw blades, as well as a saw blade itself were blasted with silica using an automated sandblasting apparatus. The blasting produced an aerosol of silica dust containing measurable amounts of blasted metals. Aerosolized samples were analyzed and evaluated for in vivo acute toxicity, DNA damage, activation of AP-1 and NF-kappaB, and potential to generate ROS. The results show that inflammatory response and pulmonary toxicity 3 days post-exposure associated with silica blasted on Sn, Ni, Saw, Cu and W being greater than silica alone. In contrast assimilation of metals, such as Cr, and Al, significantly decreased the toxicity of silica. The potential to generate ROS using a non-cellular system did not correlate with the degree of toxicity. For example, saw blade blasted with silica caused a high level of toxicity but a relatively low level of ROS generation. This is likely because metals, such as Ni, Co, and Cr, can produce greater levels of ROS in a biological milieu with reductants than in a noncellular system. Sn, saw blade, Cu and Co blasted with silica caused significantly greater levels of DNA damage compared to silica alone. The potential for DNA damage did not follow that for ROS production. Saw blade blasted with silica also caused significantly greater levels of activation of two important transcription factors, AP-1 and NF-kappaB, involved in disease development. These data suggest a potential increased risk associated with silica dust generated using concrete cutting saw.
Occupational-exposure; Metal-compounds; Metal-dusts; Metal-fumes; Metal-industry; Metal-oxides; Metal-poisoning; Metal-workers; Metallic-compounds; Metallic-dusts; Metallic-fumes; Metallic-poisons; Breathing; Breathing-zone; Pulmonary-disorders; Pulmonary-system; Pulmonary-system-disorders; Lung-burden; Lung-disorders; Lung-irritants; Respiratory-irritants; Respiratory-hypersensitivity; Respiratory-system-disorders; Toxic-vapors; Toxic-effects; Toxicopathology; Sand-blasters; Sand-blasting; Metals; Silica-dusts; Silicates; Toxins; Dusts; Dust-particles; Aerosols; Aerosol-particles; Laboratory-animals; Animals; Animal-studies
The Toxicologist. Society of Toxicology 47th Annual Meeting and ToxExpo, March 16-20, 2008, Seattle, Washington