It is important to stress from the very beginning that there exist many types of asbestos fibers. Those posing the greatest danger to human health belong to the amphibole group and include amosite (brown asbestos), anthophillite, crocidolite (blue asbestos), tremolite, and actinolite. These asbestiforms have shorter needle-like fibers whereas chrysotile fibers are silky. Amphiboles are most dangerous to human health. Being acid resistant, amphibole asbestos is almost not cleared from the lung, thus causing adverse health effect. The production and use of amphibole asbestos have been banned worldwide.
This very type of asbestos was widely used in Western countries in the past along with spraying of asbestos on metal structures of buildings for insulation purposes, so it is not by chance that the anti-asbestos movement originated in those countries. On the contrary, neither this type of asbestos nor the technique has ever been applied in CIS countries.
Chrysotile asbestos, on the other hand, is easily dissolved even by weak acids of liquid fluids and cleared rapidly. According to the results of recent studies conducted by three leading toxicological laboratories from Switzerland, Germanyand the USAchrysotile is the safest of all similar minerals and man-made mineral fibers (e.g., cellulose, aramid and ceramic fibers) since its clearance halftime is the shortest. If, for instance, the clearance halftime of chrysotile is up to 15 days, then it is 466 days for amphibole and 1 000 days for cellulose fibers. You may find more information about health effects of different fibers in the section Biopersistence of chrysotile.
Few people know that chrysotile is ubiquitous; it is found in two third of the Earth crust. Depending on the region and regardless of human or industrial activities every person inhales 10 000 to 15 000 asbestos fibers and swallows 200 000 to 2 000 000 fibers per liter of water without any damage to his health every day. Thus, chrysotile fibers accompany a man during all his life, and the human body has got accustomed to living with them.
In this connection it is important to note that the U.S. Environmental Protection Agency has accepted responsibility to revise the document published in 1986 on health risks from asbestos exposure. Nobody differentiated asbestos types then. During the conference held in California in May 2001 the Agency concluded on the necessity to update the issue and set itself a three-year period to conduct studies “in the light of new understanding, particularly concerning the difference in toxicity between chrysotile and amphiboles”.
Chrysotile poses no appreciable health risk under the exposure limit 1 fiber per cubic cm set by the ILO. The data were borrowed from many epidemiologic studies; some of them covered the period of over 20 years. Chrysotile is the safest type of asbestos, in spite of all the confusion created by some stakeholders treating all types of asbestos similarly, as a single concept.
