Asbestos cement was a composite of Portland cement and sand to which asbestos was added in amounts ranging from 5 – 10%. This was a common ingredient in cement siding used in housing construction prior to the early 1970s; the asbestos was necessary in order to compensate for the fact that cement is quite fragile at the ½” thickness used in siding and insulation.
A more common ingredient in housing insulation that is used even today is called vermiculite. By itself, vermiculite is reasonably harmless; it is essentially a form of clay which contains magnesium and iron. Like asbestos, it is fireproof; it is used not only in insulation products, but wall plaster as well. Unlike asbestos, there are few health risks posed by vermiculite – at least in its pure form.
The problem is that a great deal of vermiculite – most of which was mined at a facility located in Libby, Montana and operated by the W.R. Grace Corporation of Maryland – was contaminated with asbestos fibers. Vermiculite that came from Libby was marketed by W.R. Grace under the brand name Zonolite until the extent of the contamination forced closure of the mine in 1990. According to U.S. government figures, some 35 million homes across the nation may have Zonolite insulation installed.
In either case, if you have worked as an insulator prior to that time, are that you were exposed to those same asbestos fibers.
According to a December 2006 article in the Salt Lake Tribune, the particular form of asbestos that contaminated was called actinolite. The fibers produced by this particular form of asbestos are called amphiboles, which represent the deadliest form of asbestos. Research suggests that amphiboles are responsible for the cancer known as mesothelioma, which attacks the outer layer of the lungs (known as the pleura) and inner chest and abdominal wall in it’s most common form, known as pleural mesothelioma.
Amphibole fibers resemble hard, microscopic needles. Once inhaled, these fibers burrow into the tissue of the alveolar sacs of the lungs, ultimately working their way out onto the pleural lining. Because of their size, they can also enter the bloodstream and lymphatic system, traveling to almost any part of the body – and in the case of pregnant women, even to the fetus. This is one reason that malignant mesothelioma is likely to metastasize and/or recur even after successful treatment.
Current medical studies suggest that asbestos cancer known as mesothelioma is caused by multiple factors. The presence of amphiboles triggers a series of interactions at the DNA level that causes healthy pleural cells to become malignant. Once the cells turn cancerous, they spread over the pleural lining like a sheet, eventually restricting the lungs’ ability to expand.
Recently, a federal grand jury in Missoula, Montana indicted seven members of the board at W.R. Grace after a series of articles in the Seattle Post-Intelligencer on the company’s mining practices and the resultant illnesses suffered by the residents of Libby. According to the Justice Department, W.R. Grace may face fines of over $280 million, which is twice the amount of the company’s after-tax profits over the years. In addition, several officers of the corporation may be sentenced to prison for as long as 70 years – the first time that major corporate officers have faced criminal penalties in an asbestos case.