David N. Weissman, M.D.’s Testimony: Background of 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 explains the background of this dangerous mineral.

Asbestos is a term that is generally used to refer to a group of fibrous silicate minerals with exceptional resistance to degradation by heat, acids, bases, or solvents. The minerals are not combustible and have a high melting point and low thermal and electrical conductivity.

Their fibers can be woven or incorporated into other materials. These and other useful properties resulted in their widespread commercial application during much of the 20th century.

Unfortunately, widespread use of asbestos was followed by a marked increase in asbestos-related disease.

The definition of asbestos in many Federal regulations is limited to the fibrous forms of six specific commercial types of asbestiform minerals. One is from a class of minerals called serpentines, which have curved fibers: chrysotile.

The other five are members of a class of minerals called amphiboles, which have straight fibers: crocidolite, amosite, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos. The elemental composition of the six asbestos minerals can vary slightly, even within a single fiber, as a result of geological conditions such as pressure, temperature, or proximity of other minerals.

Recognizing these variations in elemental composition, the six asbestos minerals can be defined by their "solid-solution" mineral series. For example, the mineral series tremolite-ferroactinolite contains the asbestos mineral actinolite.

These mineral series are considered solid-solutions in which cations (i.e., sodium, calcium, magnesium, iron, etc.) are replaced by other cations which can affect the elemental composition of the mineral without significantly altering the structure.

As another example, the Libby, Montana vermiculite ore body contains amphibole asbestos fibers of the tremolite-actinolite-richterite-winchite solid solution series. The minerals in the solution series have only minor differences in chemical content and have similar, if not identical, health effects.

A third example of a mineral that produces similar diseases as asbestos is erionite, a fibrous mineral that is neither a serpentine nor an amphibole. It belongs to an entirely different class of minerals called zeolites.

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