Asbestos as a contaminant

Most respirable asbestos fibers are invisible to the unaided human eye because their size is about 3.0-20.0 µm in length and can be as thin as 0.01 µm. Human hair ranges in size from 17 to 181 µm in width.^[5] Fibers ultimately form because when these minerals originally cooled and crystallized, they formed by the polymeric molecules lining up parallel with each other and forming oriented crystal lattices. These crystals thus have three cleavage planes, just as other minerals and gemstones have. But in their case, there are two cleavage planes that are much weaker than the third direction. When sufficient force is applied, they tend to break along their weakest directions, resulting in a linear fragmentation pattern and hence a fibrous form. This fracture process can keep occurring and one larger asbestos fiber can ultimately become the source of hundreds of much thinner and smaller fibers.

As asbestos fibers get smaller and lighter, the more easily they become airborne and human respiratory exposures can result. Fibers will eventually settle but may be re-suspended by air currents or other movement.

Friability of a product containing asbestos means that it is so soft and weak in structure that it can be broken with simple finger crushing pressure. Friable materials are of the most initial concern due to their ease of damage. The forces or conditions of usage that come into intimate contact with most non-friable materials containing asbestos are substantially higher than finger pressure.

Etiology Asbestos

Asbestos Warning Sign at Bauer Elementary Miamisburg, Ohio June 2007

Health concern associated with asbestos began in the 1970s soon after Dr. Irving Selikoff, of Mt. Sinai School of Medicine, found that some workers, occupationally exposed to certain amphibole (non-serpentine) type asbestos fibers, and were at increased risk of lung disease. While Dr. Selikoff's work played a key role in removing amphibole asbestos from industry, the resulting media-driven hysteria and the EPA failed to differentiate between amphibole and chrysotile (serpentine) fibers used for asbestos. Without exception, every human study in the United States showing asbestos etiology is associated with amphibole fiber asbestos, and there is not a single study showing chrysotile etiology.