By now many people are familiar with the story of the W.R. Grace vermiculite mine in Libby, Montana. Grace owned and operated the mine from 1960 to 1993, mining an ore that is heated, crushed and then used for insulation products. The vermiculite in the Libby mine is contaminated with tremolite asbestos.
The result has been the deaths of at least two hundred Libby residents due to asbestos related diseases such as mesothelioma. Thousands more have been impacted by the dust generated in the mining process and may expect to develop potentially fatal asbestos diseases in the future.
Tremolite Not the Most Common Form of Asbestos
Tremolite is not the common form of asbestos found in most of the asbestos products that were so popular during the twentieth century. There are six forms of mineral deposits that are referred to as asbestos: chrysotile, amosite, crocidolite, tremolite, anthophyllite and actinolite.
Chrysolite is by far the most common, comprising perhaps ninety five percent of the asbestos products found in buildings in the United States today. Ironically, chrysolite is the only form of the mineral that has curly fibers. Tremolite and the other variations are all needle-like in form, perhaps even more likely to damage lung tissue.
Toxicity of Tremolite Asbestos
Tremolite is just as toxic as chrysolite, if not more so. When shipments of the vermiculite ore left Libby, they were sent to at least twenty six regional plants across the country that produced insulation from the ore and sold it under the brand name Zonolite to uncounted numbers of contractors, builders and do-it-yourself homeowners. Millions of tons of the ore were shipped just during the years when W.R. Grace owned the company.
The process for using vermiculite involves heating the ore at a very high temperature, which leaves residue in the form of slag rock. The slag was also contaminated with tremolite asbestos, and used in many yards as a form of gravel or soil covering in flower beds. The spread of tremolite asbestos from this one mine is probably enormous. At least one Alaskan homeowner has reported a lung condition related to Zonolite that was sold into the Alaskan market by a Canadian distributor.
Finding Products with Tremolite Asbestos
Cautious people should be on the lookout for asbestos products in any building they own or live in. In particular, however, if Zonolite insulation appears in a building wall, call for the asbestos removal specialists and stay away from it. The tremolite from Libby, Montana lives on in thousands of buildings constructed or remodeled during the years when W.R. Grace was selling its Zonolite insulation across the nation.