Asbestos

Asbestos is a fibrous incombustible mineral composed of magnesium and calcium silicates with or without other elements. Unlike many other minerals, asbestos is characterized by crystal formation that takes the form of long thin fibers. Asbestos is divided into two mineral groups --- Serpentine and Amphibole. This division is based upon the crystalline structure. Serpentine asbestos has a sheet-like or layered structure. Amphibole asbestos has a chain-like structure.

Chrysotile - the sole member of the serpentine group - is the most common type of asbestos found in buildings. Also known as "white asbestos," chrysotile makes up 90%-95% of all asbestos contained in buildings in the United States.

There are five types of asbestos in the amphibole group. Amosite (named as a type of acronym for Asbestos Mines of South Africa) is the second most common type of asbestos found in building materials. Amosite is also called "brown asbestos." Crocidolite or "blue asbestos," which is an amphibole type found in specialized high temperature applications. Anthophyllite, Tremolite, and Actinolite are three other types of amphibole asbestos, although these types are rare and found mainly as contaminants in other minerals. Asbestos deposits exist worldwide, and asbestos is still mined in Australia, Canada, South Africa, and Russia.

Inhalation of asbestos dust can causes asbestosis, a fibrosis of the lungs, and eventual lung, gastrointestinal and mesothelioma (body cavity lining) neoplasms. Some types of asbestos are more likely to cause disease than others. Crocidolite asbestos has the greatest diseae-causing potential followed by chysotile and amosite.

Because of asbestos' unique properties, including its fireproof characteristics, asbestos was used as a component of a variety of products including fireproofing materials, insulation, plaster, decorative ceiling tiles, and brake linings. Asbestos is also a common contaminant of talc and therefore may be found in such consumer products as talcum powder, contraceptive diaphragms, condoms, rubber balloons and childrens crayons (although crayon manufacturers were mandated to remove talc from their products by 2001).

Dietary sources of asbestos include drinking water, which may be contaminated by naturally occurring asbestos, deterioration of asbestos-cement water pipes or the leeching into groundwater of asbestos from asbestos-containing products that have been disposed of in landfills. In a few instances, beverages such as wine and beers have been reported to be contaminated with asbestos either because contaminated water was used to make the beverage or because of contact with asbestos-containing pads used in the filtration process. In addition, the use of older stoves and toasters may result in exposure to asbestos since if asbestos-containing materials were used as components in some older stoves and toasters.

People with increased risk of asbestos exposure include those involved in the mining and milling of asbestos, the manufacturing of products that contain asbestos, the construction of buildings and ships that use asbestos-contaminated materials or the installation of such materials. Individuals who live, work or spend extensive time (such as school children) in buildings that have deteriorating asbestos insulation or fireproofing materials may also be at risk for exposure. Individuals who live near freeways may also have greater exposure since airborne asbestos levels are higher in these areas probably due to the breakdown of asbestos-containing brake linings.

Due to its classification as a human carcinogen, asbestos was banned for use in many new products in 1991 with its use in other products phased out in the succeeding ten years. Yet, since asbestos use was widespread between the 1940s and 1970s, there are still significant exposure vectors existing. For example, when buildings that contain asbestos materials are eventually torn down or when asbestos-containing products are disposed of and abandoned to landfills or incinerators, the asbestos fibers can be discharged back into the environment, through the air, soil and groundwater, creating potential sources of toxic exposure. Therefore, what is of concern is not just direct exposure to toxic materials such as asbestos but also indirect exposure.

People with increased risk of asbestos exposure include those involved in the mining and milling of asbestos, the manufacturing of products that contain asbestos, the construction of buildings and ships that use asbestos-contaminated materials or the installation of such materials. Individuals who live, work or spend extensive time (such as school children) in buildings that have deteriorating asbestos insulation or fireproofing materials may also be at risk for exposure. Individuals who live near freeways may also have greater exposure since airborne asbestos levels are higher in these areas probably due to degradation of asbestos-containing brake linings.

Due to its classification as a human carcinogen, asbestos was banned for use in many new products in 1991 with the use of it in other products phased out in the succeeding ten years. Yet, since asbestos use was widespread between the 1940s and 1970s, there are still significant exposure vectors existing. For example, when buildings that contain asbestos materials are eventually torn down or when asbestos-containing products are disposed of and abandoned to landfills or incinerators, the asbestos fibers can be discharged back into the environment, through the air, soil and groundwater, creating potential sources of toxic exposure. Therefore, what is of concern is not just direct exposure to toxic materials such as asbestos but also to indirect exposure.

Due to unique properties, including its fireproof characteristics, asbestos was used as a component of a variety of products including fireproofing materials, insulation, plaster and decorative ceiling tiles, and brake linings. Asbestos is also a common contaminant of talc and therefore may be found in such consumer products as talcum powder, contraceptive diaphragms, condoms, rubber balloons and childrens crayons (although crayon manufacturers were mandated to remove talc from their products by 2001).

Dietary sources of asbestos include drinking water whose contamination may be due to a variety of factors: naturally occurring asbestos, deterioration of asbestos-cement water pipes or the leeching into groundwater of asbestos from asbestos-containing products that have been disposed of in landfills. There have been select reports of beverages such as wine and beers being contaminated with asbestos either caused by contaminated water used to make the beverage or through contact with asbestos-containing pads used in the filtration process. In addition, dietary exposure may occur if there is deterioration of asbestos materials that had been used as components of some older stoves and toasters.

Human carcinogen. Banned

Asbestos is known to cause cancer of the lungs and colon, among other organs, as well as mesotheliomas, cancer of the body cavity membrane linings. Exposure to asbestos has also been linked to other noncancerous conditions such as asbestosis, a disease characterized by fibrosis of the lungs. The potential to cause disease varies according to the type of asbestos, with crocidolite having the greatest potential followed by chysotile and amosite.