Vermiculite is a natural mica-like mineral. Chemically, it is a hydrated magnesium-aluminum silicate formed millions of years ago by natural alterations of mica. When heated, it expands about 15 times in volume, making it a valuable material for use in manufacturing, construction and agriculture. What are vermiculite's attributes? heat resistant chemically inert (won't decompose or react with other chemicals) high insulating value very absorbent How is vermiculite used? masonry fill concrete aggregate soil mixes fireproofing swimming pool base insulation packing material Does vermiculite contain asbestos? Almost all vermiculite deposits worldwide are found in geological formations which contain asbestos materials to varying degrees. Grace invested millions of dollars developing and implementing a multi-step purification process to remove tremolite from vermiculite that it mined. Is all asbestiform tremolite removed in the processing of vermiculite ore? Expanded vermiculite--the finished product--contains only trace amounts of asbestiform tremolite, indicating a tremolite content of less than 1/1000th of 1% on a dry weight basis. As in all industrial purification processes, complete removal of trace minerals is not possible. When Grace processed vermiculite, it also performed air-sampling tests to determine possible concentrations of airborne fibers to which workers might be exposed under job site conditions. In tests performed during the mid-80s, all measurements showed airborne concentrations below reliably detectable levels. As a result, we believed that when our products were used in accordance with instructions, they posed no unreasonable health risk. What happened to vermiculite when it left Libby? Vermiculite was shipped from the mines usually by rail, to expansion plants for final processing. Through the application of heat, the vermiculite was expanded to several times its volume. How many expansion plants did Grace operate? In the mid-80s, Grace operated 29 expanding plants in the U.S. and five in Canada. Vermiculite was also processed for Grace through four licensees. How many people did Grace employ in its expansion plants? 500 What safety awareness programs did Grace implement for its expansion plant employees? Grace maintained full-scale safety awareness programs at its vermiculite expanding plants. An annual x-ray program was implemented in 1971, and lung function tests were begun in 1974. New employees were briefed on any possible health hazards, and in 1984 a video explaining the dangers of dust, asbestos exposure and smoking was produced for all employees. What were the regulations establishing exposure limits for workers? The Occupational Safety and Health Administration (OSHA) established standards for permissible exposure to airborne concentrations of asbestos fibers. These standards, as they were revised in 1976, set permissible worker exposure at a concentration of two fibers per cubic centimeter (2 f/cc) of air for an eight-hour day. At the time the Mine Safety and Health Administration (MSHA) established the same standards in the 1980s, worker exposure levels at the Libby mine were 0.1 f/cc, 20 times below the MSHA standard. Were people exposed to an increase of airborne asbestos fibers when vermiculite-based products were used? In the late 1970s, Grace conducted air-sampling tests of Zonolite® Attic Insulation, a product primarily used in older homes to retrofit or add to existing insulation. Designed to replicate the installation procedure in typical homes, air sampling was conducted prior to, during and after installation. The results: Asbestos fibers in the attic space during installation were at a level well below what was then considered a permissible lifetime occupational exposure. Air sampling indicated no asbestos fibers were detected in the attic within six hours after installation. Based on these results, Grace concluded that no unreasonable risk of injury was posed to a homeowner installer. Are there any safety precautions that workers should use when handling vermiculite-based products? Yes. Grace published material safety data sheets, which detailed appropriate precautions for working with its products.