Types of Asbestos
How Asbestos Is Classified and Used
Mined and used commercially for many years, asbestos has been linked to many diseases including mesothelioma, lung cancer, and asbestosis. The U.S. government now regulates six forms of asbestos. However, the U.S. Bureau of Mines has identified over 100 types of asbestos-like fibers, leading some to call for further regulation. Currently, no other fibrous minerals have been banned from the market.
The six different asbestos fibers fall into one of two mineral groups: serpentine and amphibole. Serpentine asbestos has fibers that are curly and flexible, while amphibole fibers are straight and needle-like. Amphiboles are considered more dangerous, but serpentine asbestos was more commonly used in commercial products. The Environmental Protection Agency (EPA) identifies both forms as carcinogens.
Serpentine Asbestos (Chrysotile)
The mineral group “serpentine” includes only one variety—chrysotile. Also known as “white” or “green” asbestos, this is the most plentiful type of asbestos. Some researchers argue chrysotile’s curly structure makes it more easily dislodged from tissues, and therefore less likely to cause disease than the amphibole variety. For these reasons, some scientists consider it a lesser toxic mineral fiber. Still, because it is so widespread compared to the other varieties of asbestos, it accounts for a majority of health problems associated with exposure.
Chrysotile is used in cement, as flat sheets for ceilings, walls and floors, and to provide friction in braking systems.
Amphibole Asbestos
The amphibole mineral group is less commercially used but more dangerous than the serpentine group. Amphiboles have varying degrees of friability. In general, they are more likely to crumble than chrysotile. With their needle-like structures, they can easily be embedded in the body’s tissues, increasing the person’s chances of developing mesothelioma and other serious health conditions.
Crocidolite
Also known as “blue asbestos” or “riebeckite,” crocidolite is thought to be the most toxic variety of mineral fibers. Its color ranges from slate gray to deep blue. Its fibers are hair-like, long, and straight. Crocidolite was primarily mined in South Africa and Australia; however, its comparatively poor heat resistance combined with danger to workers means it is no longer mined. It is estimated that 18% of crocidolite miners died from mesothelioma, and the people living in areas around old these mines still suffer from the exposure.
Crocidolite was used primarily in cement products.
Amosite
Called “brown asbestos,” amosite is the second-most dangerous type of asbestos (under crocidolite). At one point, it was also the second-most popular type of asbestos used in commercial products.
Amosite fibers are straight but brittle. It is now banned in many countries due to its high friability, but can still be found in older structures, where it was used for a time as a flame retardant. Amosite was mined in South Africa, and many miners have died from asbestos-related diseases during and in years since its use.
Anthophyllite
Sometimes called “grey asbestos,” anthophyllite often contaminates talc, the mineral it forms from. Anthophyllite fibers, like others in the amphibole mineral group, are straight and brittle. The material was mined in Europe, Asia, and the United States.
Because it is derived from talc, it has been known to contaminate talc products such as talcum powder. Talcum powder can be used as a deodorant and a baby powder. Anthophyllite was also was commonly used in paints and sealants.
Tremolite
Varying in color from white to green, tremolite is the main contaminant of industrial and commercial talc. It is also highly carcinogenic. In one study of mesothelioma patients, half the subjects had inhaled fibers of this type.
Like anthophyllite, tremolite can also be found in talcum powder. It is found in most metamorphic rocks.
Actinolite
This mineral’s colors range from white to gray or brown to green, and it comes in two forms: compact or dense, or fibrous and brittle. Actinolite was commonly used as an insulator and is still in many older homes and other buildings. Thousands of people are unknowingly exposed to this material because of this.
Actinolite has also been found in drywall compounds and children’s toys.