How to Identify Asbestos
Types and Associated Fibers
Six minerals are defined by the United States Environmental Protection Agency as "asbestos". The minerals belong in two classes: serpentine and amphibole.
There are great differences between the two classes dependent on their chemical composition and their degree of potency as a health hazard when inhaled. However, all commercial forms of asbestos are known to be carcinogens in humans.
Chrysotile is obtained from serpentinite rocks which are common throughout the world.. Chrysotile fibers are curly as opposed to fibers from amosite, crocidolite, tremolite, actinolite, and anthophyllite which are needlelike. Chrysotile, along with other types of asbestos, has been banned in dozens of countries and is only allowed in the United States and Europe in very limited circumstances. Chrysotile has been used more than any other type and accounts for about 95% of the asbestos found in buildings in America. Applications where chrysotile might be used include the use of joint compound. It is more flexible than amphibole types of asbestos; it can be spun and woven into fabric. The most common use is within corrugated asbestos cement roof sheets typically used for outbuildings, warehouses and garages. It is also found as flat sheets used for ceilings and sometimes for walls and floors. Numerous other items have been made containing chrysotile including brake linings, cloth behind fuses (for fire protection), pipe insulation, floor tiles, and rope seals for boilers
Serpentine minerals have a sheet or layered structure. Chrysotile is the only asbestosmineral in the serpentine group. In the United States, chrysotile has been the most commonly used type of asbestos. According to the U.S. EPA Asbestos Building Inspectors Manual, chrysotile accounts for approximately 95% of asbestos found in buildings in the United States. Chrysotile is often present in a wide variety of products and materials, including:
- drywall and joint compound
- gas mask filters pre 1960s
- mud and texture coats
- vinyl floor tiles, sheeting, adhesives
- roofing tars, felts, siding, and shingles
- "transite" panels, siding, countertops, and pipes
- popcorn ceilings, also known as acoustic ceilings
- packing, a system for sealing a rotating shaft
- brake pads and shoes
- clutch plates
- stage curtains
- fire blankets
- interior fire doors
- fireproof clothing for firefighters
- thermal pipe insulation
- filters for removing fine particulates from chemicals, liquids and wine
- dental cast linings
- HVAC flexible duct connectors
- drilling fluid additives
A household heat spreader for cooking on gas stoves, made of asbestos (probably 1950s;
In the European Union and Australia it has recently been banned as a potential health hazard and is not used at all. Japan is moving in the same direction, but more slowly. Revelations that hundreds of workers had died in Japan over the previous few decades from diseases related to asbestos sparked a scandal in mid-2005. Tokyo had, in 1971, ordered companies handling asbestos to install ventilators and check health on a regular basis; however, the Japanese government did not ban crocidolite and amosite until 1995, and a full-fledged ban on asbestos was implemented in October 2004.
Five types of asbestos are found in the amphibole group: amosite, crocidolite, anthophyllite, tremolite, and actinolite.
Amosite commonly from South Africa, the second most likely type to be found in buildings, according to the U.S. EPA Asbestos Building Inspectors Guide, is the "brown" asbestos. It is found most frequently as a fire retardant in thermal insulation products and ceiling tiles.
Crocidolite is an amphibole found primarily in southern Africa, but also in Australia. Crocidolite commonly occurs as soft friable fibers. Asbestiform amphibole may also occur as soft friable fibers but some varieties such as amosite are commonly straighter. All forms of asbestos are fibrillar in that they are composed of fibers with breadths less than 1 micrometer that occur in bundles and have very great widths. Asbestos with particularly fine fibers is also referred to as "amianthus". Amphiboles such as tremolite have a crystal structure containing strongly bonded ribbonlike silicate anion polymers that extend the width of the crystal. Serpentine (chrysotile) has a sheetlike silicate anion which is bowed and which rolls up like a carpet to form the fiber.
Other regulated asbestos minerals, such as tremolite asbestos, actinolite asbestos and anthophyllite asbestos, are less commonly used industrially but can still be found in a variety of construction materials and insulation materials and have been reported in the past to occur in a few consumer products.
Amosite and crocidolite were formerly used in many products until the early 1980s. The use of all types of asbestos in the amphibole group was banned in much of the Western world by the mid-1980s, and by Japan in 1995. These products were mainly
- Low density insulating board (often referred to as AIB or asbestos insulating board) and ceiling tiles;
- Asbestos-cement sheets and pipes for construction, casing for water and electrical/telecommunication services;
- Thermal and chemical insulation (e.g., fire rated doors, limpet spray, lagging and gaskets).