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  • crystalline silica
  • Industry stakeholders, worker advocates and public health experts are delivering testimony and cross-examining one another on proposed changes to the rules governing workplace exposure to crystalline silica. (shrm.org)
  • The current permissible exposure limit (PEL) for respirable crystalline silica has not been updated since the agency's creation in 1971. (shrm.org)
  • The current general industry PEL for quartz, the most common form of crystalline silica, is roughly 100 micrograms per cubic meter of air (100 ug/m3) as an eight-hour time-weighted average. (shrm.org)
  • The current PELs for two other forms of crystalline silica (cristobalite and tridymite) are one-half the values for quartz in general industry. (shrm.org)
  • More than 2 million workers are exposed to respirable crystalline silica each year, according to OSHA. (shrm.org)
  • Occupational exposure to crystalline silica happens during the cutting, sawing, drilling and crushing of concrete, brick, rock and stone. (shrm.org)
  • NIOSH testified that extended occupational exposure to respirable crystalline silica can lead to the lung disease silicosis, as well as lung cancer, pulmonary tuberculosis, airways diseases, autoimmune disorders, chronic renal disease and other adverse health effects. (shrm.org)
  • Each year, an unknown number of workers are exposed to the hazards of respirable crystalline silica. (buildsafe.org)
  • Illustrations are not available in the PDF version of the Crystalline Silica Primer. (usgs.gov)
  • Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. (usgs.gov)
  • From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. (usgs.gov)
  • Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. (usgs.gov)
  • During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. (usgs.gov)
  • As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). (usgs.gov)
  • Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. (usgs.gov)
  • Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated businesses may choose to do so if they wish to show that they are exempt from the requirements of HCS. (usgs.gov)
  • Because crystalline silica is an extremely common mineral and the HCS will affect many mineral commodities, it is important then, that there be as clear an understanding as possible of what is and what is not crystalline silica, and where it is found and used, and how it is qualitatively and quantitatively identified. (usgs.gov)
  • This primer will examine crystalline silica. (usgs.gov)
  • Part I will describe, in nonscientific terms, what crystalline silica is and how we come in contact with it. (usgs.gov)
  • Part II will discuss the regulatory decisions that have created new interest in this ancient and widespread substance and will present a nontechnical overview of the techniques used to measure crystalline silica. (usgs.gov)
  • Because this primer is meant to be a starting point for anyone interested in learning more about crystalline silica, a list of selected readings and other resources is included. (usgs.gov)
  • powder
  • flame-fused silica glasses from sol-gel silica powder," Journal of Non-Crystalline Solids , vol. 179, pp. 328-334, 1994. (hindawi.com)
  • Stabilizing silica gel - non-crystalline micro-porous solid powder, nontoxic, flame-resisting, used in brewery of grains for beer to improve taste, clearness, color and foam, removal of non-micro-organism impurities. (wikipedia.org)
  • These improvements stem from both the mechanical improvements resulting from addition of a very fine powder to the cement paste mix as well as from the pozzolanic reactions between the silica fume and free calcium hydroxide in the paste. (wikipedia.org)
  • resins
  • citation needed] Methods using silica beads and silica resins have been created that can isolate DNA molecules for subsequent PCR amplification. (wikipedia.org)
  • Silica structures are therefore easier to use in highly parallelized designs than beads or resins. (wikipedia.org)
  • Evaluation of Silica Resins for Direct and Efficient Extration of DNA from Complex Biological Matrices in a Miniaturized Format.Analytical Biochemistry 283, 175-191 (2000). (wikipedia.org)
  • adsorption
  • However, material silica gel removes moisture by adsorption onto the surface of its numerous pores rather than by absorption into the bulk of the gel. (wikipedia.org)
  • DNA separation by silica adsorption is a method of DNA separation that is based on DNA molecules binding to silica surfaces in the presence of certain salts and under certain pH conditions. (wikipedia.org)
  • Driving Forces for DNA Adsorption to Silica in Perchlorate Solutions. (wikipedia.org)
  • bulk
  • Ritsko, J. E. and Vanderpool, C. D. "Process for producing low-bulk density silica. (wikipedia.org)
  • Diatoms account for 43% of the ocean primary production, and are responsible for the bulk of silica extraction from ocean waters in the modern ocean, and during much of the past fifty million years. (wikipedia.org)
  • reactive
  • An integral part of my work includes using self-assembly coupled with synthetic chemistry techniques to functionalize silica materials with reactive binding sites. (nsti.org)
  • microscopic
  • During their life cycles, microscopic diatoms pull silicic acid out of the water and store large amounts of crystallized silica in their outer cell walls. (maximumyield.com)
  • Silica gel is often described as "absorbing" moisture, which may be appropriate when the gel's microscopic structure is ignored, as in silica gel packs or other products. (wikipedia.org)
  • aggregate
  • When this latter is completely filled, if the soluble but very viscous gel cannot be easily expelled from the silica network, the hydraulic pressure raises inside the attacked aggregate and leads to its fracture. (wikipedia.org)
  • workplace
  • SGS has the expertise, equipment and experience to provide the silica analysis you need to monitor the safety of your workplace and keep your staff healthy. (sgs.com)
  • occupational
  • Some say the Occupational Safety and Health Administration's (OSHA) proposed rule to protect silica-exposed workers is decades overdue. (shrm.org)
  • OSHA's proposed new PEL-50 micrograms per cubic meter of air to cover all three silica types for all industry sectors-was first recommended by the National Institute for Occupational Safety and Health (NIOSH) in 1974. (shrm.org)
  • minerals
  • It is my purpose to discuss the various silica minerals. (minsocam.org)
  • They are, moreover, of considerable geological interest, and altogether we have a fairly good idea of the role that the silica minerals play in Nature. (minsocam.org)
  • Let us first consider briefly the silica minerals and their properties as a background for the discussion of their natural history. (minsocam.org)
  • nutrient
  • The results of this study suggest that silica is a nutrient of concern in wound healing as well as bone formation. (essense-of-life.com)
  • In fact, it would be difficult, if not impossible, to include silica directly in a concentrated nutrient formula. (maximumyield.com)
  • calcium
  • Silica helps to promote the body's absorption of calcium, an important component in tissue repair and bone and cartilage formation. (essense-of-life.com)
  • This product is comprised of precisely sized, high-purity fused silica, silicon carbide and a calcium aluminate binder. (3m.com)
  • Hydrogen
  • Silica is inert to most chemical reagents but reacts with hydrogen fluoride to form silicon tetrafluoride , which is a colourless gas at room temperature and water. (everything2.com)
  • spicules
  • Some of the most common siliceous structures observed at the cell surface of silica-secreting organisms include: spicules, scales, solid plates, granules, frustules, and other elaborate geometric forms, depending on the species considered. (wikipedia.org)
  • diatoms
  • Firstly, the modern marine silica cycle is widely believed to be dominated by diatoms for the fixation and export of particulate matter (including organic carbon), from the euphotic zone to the deep ocean, via a process known as the biological pump. (wikipedia.org)
  • As a result, diatoms, and other silica-secreting organisms, play a crucial role in the global carbon cycle, and have the ability to affect atmospheric CO2 concentrations on a variety of time scales, by sequestering CO2 in the ocean. (wikipedia.org)
  • The remains of diatoms and other silica-utilizing organisms are found, as opal sediments within pelagic deep-sea deposits. (wikipedia.org)
  • varieties
  • Our fused silica castables come in six varieties to fit your specific needs. (3m.com)
  • Two varieties of 2D silica, both of hexagonal crystal symmetry, have been grown so far on various metal substrates. (wikipedia.org)