David N. Weissman, M.D.’s Testimony: minerals treated as asbestos

Read more from the testimony of Dr. Weissman, who spoke before the Senate’s Committee on the Environment and Public Works about the dangers of asbestos. In this section, he discusses the regulatory definitions of minerals that can be classified as containing asbestos.

As already described, most regulatory definitions of asbestos do not explicitly include minerals such as winchite, richterite, and erionite, despite the known similar health effects of their fibers to those of the explicitly listed asbestos minerals.

In addition, significant controversy exists regarding other types of mineral particles that have the dimensions of fibers. For example, El Dorado, California, is a site with natural deposits of amphibole that have been disturbed by construction and crushing of rock.

Analyses of air and rock samples have identified the presence of actinolite in the form of needle-like crystalline structures called “acicular/prismatic actinolite.”

Although many of these amphibole particles meet the dimensional criteria of asbestos fibers, they have a different crystalline structure from fibrous actinolite asbestos.

A recent report by investigators from the University of California found that residential proximity to deposits of “naturally occurring asbestos” such as those in the vicinity of El Dorado was associated with increased risk for mesothelioma, implicating these minerals as a possible health hazard.

It should be noted that this report did not include actual measurement of fiber exposures associated with residence in these areas.

Asbestos minerals have analogs that are crystallized in non-asbestiform (massive) structures. A controversial type of mineral particle is the “cleavage fragment," which can be generated from massive forms of these analog minerals during their handling, crushing, or processing, as occurs in mining and construction.

Using current analytical methods based on light microscopy, these “cleavage fragments” are often microscopically indistinguishable from asbestiform fibers of their asbestos mineral counterparts. The toxic potential of these mineral particles, in particular their carcinogenicity, has been an area of great controversy.

Courtesy of EPA

Other helpful links:

Asbestos Asbestos
Asbestos and lung cancer Asbestos and lung cancer
Mesothelioma attorney Mesothelioma attorney
Mesothelioma Lawyer Mesothelioma lawyer
Asbestos attorney Asbestos attorney