Uses of asbestos, health effects related to asbestos exposure, dealing with asbestos in the home, etc.
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Asbestos is a general name given to some types of naturally occurring minerals that can be found throughout the world in certain types of rocks. The asbestos found in these rocks can be separated into very fine and extremely durable fibers.
Asbestos minerals can be divided into two basic categories,Serpentine asbestos and Amphibole asbestos. The difference between the categories of asbestos minerals stems from the physical characteristics of the two groups. Serpentine asbestos develops in a layered or tiered form, whereas Amphibole asbestos has a chain-like structure.
Chrysotile, commonly known as "White Asbestos", is the only form of Serpentine asbestos and makes up almost 95% of all the asbestos used for commercial purposes in the United States.
Unlike Serpentine asbestos, Amphibole asbestos can be found in the following five forms:
- Amosite or "Brown Asbestos"
- Crocidolite or "Blue Asbestos"
Of these five forms of Amphibole asbestos, only Amosite and Crocidolite were commonly used in commercial products.
Asbestos-related Health Effects
Since the mid-1900's, many studies have been performed to determine the possible health effects associated with exposure to asbestos fibers. The results of these studies have indicated that high levels of exposure to airborne asbestos fibers may cause a variety of pulmonary (involving the lungs and breathing) diseases. The most notable of the diseases associated with asbestos is Asbestosis. Asbestosis is the scarring of the tissues of the lungs (including the alveoli, tiny air sacs where the primary exchange of oxygen occurs between the air and blood, see below) which causes a reduction in lung capacity. The relationship between the development of Asbestosis and exposure to airborne asbestos is dose related. Therefore, the greater the asbestos exposure, the greater the likelihood of developing Asbestosis.
Although Asbestosis has been positively linked to asbestos exposure, it may be years after the exposure before disease develops. In fact, Asbestosis typically has a latency period of 15-30 years after exposure. Other asbestos related respiratory diseases include Mesothelioma, pleural (the body cavity that surrounds the lungs) abnormalities, and lung cancer. Studies have also shown exposure to airborne asbestos fibers may cause cancer of the esophagus, colon, pancreas, and stomach.
NOTE: Although it has been documented that exposure to asbestos may cause an increased risk of developing one of the diseases mentioned above, it should be made clear that the results of the studies are based on exposure to airborne asbestos fibers. If an asbestos-containing material is in good condition and is not damaged to the point that asbestos fibers are released, there is little chance of exposure to potentially dangerous airborne asbestos fibers.
The History of Asbestos
Asbestos' resilient properties have made it a useful tool for centuries.
The ancient Greeks took advantage of the durability of asbestos fibers by spinning
asbestos fibers into cloth to be used as blankets and tablecloths. Since asbestos
fibers are resistant to fire, the ancient Romans used asbestos in the wicks of their
Although the usefulness of asbestos has been known for centuries, it was not until the late 19th century when large deposits of asbestos were discovered in parts of Canada and the northern United States that the emergence of asbestos as a common construction material occurred. The relatively inexpensive production and mass abundance of asbestos-containing materials created a widespread desire to utilize asbestos in building materials. Experimentation with the mineral revealed that asbestos was an excellent fire retardant, an exceptional component of acoustical plaster, and a decorative material. The use of asbestos was not, however, limited to the construction industry. Asbestos was used in the making of fire resistant clothing for fire fighters and hot pads used in food production. Asbestos was also used by the automotive industry in such things as brake shoes and clutch fittings for cars and trucks. In fact, at one time asbestos could be found throughout the country in products ranging from thermal insulation to kitty litter.
It was not until the early 1970's, when studies began to show adverse health effects related to asbestos-containing materials, that the widespread use of asbestos began to slow. Companies began to develop substitutes for asbestos-containing materials and began to remove asbestos from the market. Regulations were developed dealing with the manufacturing and removal of asbestos-containing materials and the massive asbestos mining efforts were abandoned. In some cases, however, a reasonable substitute for asbestos could not be found. Therefore, a few asbestos-containing products are still manufactured today.
Asbestos in its Many Forms
Asbestos is used in products of various forms and appearances. The following is a small list of the common types of asbestos-containing materials:
- Thermal Insulation - Pipe Insulation, Boiler Insulation, etc.
- Surfacing Materials - Plaster, Paint, Spackling Compound, Stucco, Wall Joint Compound
- Spray-On Materials - Acoustic Ceiling Spray, Decorative Spray, Insulation Spray
- Roofing Materials - Asphalt Roofing Shingles, Roofing Felt Paper, Roof Flashing, Built-up Roofing, Slate Roofing Shingles
- Flooring Materials - Floor Tiles, Vinyl Flooring, Linoleum, Terrazzo Tiles
- Cement Products - Cement Siding, Cement Piping
- Miscellaneous Materials - Ceiling Tiles, Floor Glue (Mastic), Gloves, Sealants, Packings, Gaskets, Vinyl Wall Paper, Lab Bench Tops & Aprons, Fire Blankets, Fire Doors, Theater & Welding Curtains, Automobile Brake Pads, etc.
Asbestos in the Home
There are only two ways to determine if a material contains asbestos. The first way is to contact the manufacturer of the product. If you are not sure who the manufacturer of the product is, the individuals who installed the material may know. If you are unable to track down the origin of the material, the only other way to determine if asbestos is present it to have the material tested by a laboratory. In order for a lab to determine if a material has asbestos in it, a sample must be studied under a microscope.
Samples of suspect asbestos-containing material from a private residence can be taken by asbestos professionals or by the homeowner himself.
A list of asbestos professionals can be found here or by checking the yellow pages of your local phone book under the heading "Environmental Consultants". A list can also be obtained from DHEC free of charge. If you decide to sample a suspect asbestos-containing material yourself, there are certain precautions that should be taken.
Removing Asbestos from the Home
Asbestos-containing materials can be found in two forms in your home. These forms are called friable asbestos-containing material and non-friable asbestos-containing material. The distinction between friable and non-friable asbestos lies in the physical condition of the material.
Friable asbestos-containing material is material that can be reduced to powder by hand pressure. Insulation and textured ceiling spray are two common examples of friable asbestos-containing material.
Non-friable asbestos-containing material is material that has asbestos fibers bound in a hard or durable matrix. The asbestos fibers in non-friable asbestos-containing material are typically not easily made airborne. These types of materials are usually considered much safer than friable asbestos-containing material. Non-friable asbestos-containing material can, however, be damaged to the point that it becomes friable. Examples of non-friable asbestos-containing material include asbestos siding and roofing material. Usually, non-friable asbestos-containing material can safely be removed from residential property either by a licensed asbestos abatement contractor or by the homeowner. If the homeowner chooses to remove the material himself, certain precautions should be taken. The following are some suggested removal techniques for common non-friable asbestos-containing materials:
Transite Siding - First, mist the material with water to reduce the chance of fibers becoming airborne. Next, the material should be removed with as little breakage as possible. This can be done by cutting off the heads of the nails or screws that hold the siding in place and sliding the panels away from the wall. Once the material is unfastened from the wall, carefully lower the siding to the ground. Finally, wrap the siding and seal it with duct tape.
Asbestos Flooring - There are several methods for safely removing asbestos flooring material. One such way is to use heat to loosen the flooring from the subfloor. While holding a heat gun over an edge of the flooring, use a putty knife to lift the asbestos flooring away from the subfloor. Continue heating and lifting small areas at a time until the material is completely free. Once the asbestos flooring has separated from the subfloor, the material should be wetted down and wrapped in plastic. Another method for removing asbestos flooring is to use a putty knife to pry the flooring up while continually wetting the material. The water should keep any fibers that are released from becoming airborne. Dry ice can also be used to freeze the adhesive holding the flooring to the subfloor. When the adhesive freezes, the floor covering should be released from the subfloor.
Asbestos Roofing - Asbestos roofing shingles can be removed as a non-friable material provided it is not severely damaged during removal. Asbestos-containing asphalt shingles can be removed by prying the shingles away from the nails and lowering them to the ground. As in all asbestos removals, the material should be wet during the project. However, on steep pitched roofs, too much wetting may result in a slick surface increasing the chance of a fall. If it is not safe to wet the material during removal, extra precautions should be taken to remove the material with as little breakage as possible. Once the material is lowered to the ground, it should be misted and wrapped in plastic.
Although the removal of friable asbestos-containing material in private residences is not generally regulated, DHEC does not recommend that any person engage in such activity unless trained to do so. Contractors specializing in asbestos abatement can be found at this website under List of Contractors or in your local yellow pages. A list of licensed contractors is also available through the Department free of charge.
Generally, asbestos-containing material does not have to be removed from residential property. In fact, asbestos-containing material does not have to be removed from any structures unless it will be disturbed during renovation or demolition acitivities. As long as asbestos-containing material is in good condition and will not be disturbed, it does not pose a significant health risk.
Homeowners with Damaged Asbestos Roofing or Siding
Homeowners who choose to repair or replace damaged asbestos roofing or siding have three options. They can do the work themselves, hire a general contractor who is not licensed to perform asbestos abatement, or hire a licensed asbestos abatement contractor. DHEC regulations do not apply to work done at private residences unless the homeowner selects a licensed asbestos abatement contractor, in which case the contractor must comply with asbestos regulations.
All contractors should comply with Occupational Safety and Health Administration (OSHA) rules for worker protection.
If the homeowner wishes to do the work himself or if he hires a general contractor not licensed by DHEC to perform asbestos abatement, DHEC recommends the following work practices and procedures to minimize airborne asbestos fiber releases and personal exposure:
- Keep the material wet at all times. A low pressure garden sprayer adjusted to "mist" can be used. Water helps keep asbestos fibers from becoming airborne.
- Avoid tearing, ripping, chipping, cutting, or grinding asbestos-containing materials. These actions create new surfaces where there is the greatest potential for release of asbestos fibers.
- Do not throw or drop asbestos-containing roofing or siding materials to the ground. Instead lower them carefully to prevent breakage and dispersal.
- Place asbestos waste in polyethylene bags at least 6 millimeters (6-mil) in thickness, or wrap it in two layers of 6-mil polyethylene sheeting sealed with tape. Additional water may be added to ensure thorough wetting, but do not add so much that the bag bursts when lifted.
- Debris already on the ground should be wet and either collected manually or shoveled up and bagged for disposal. These residual materials can be pulverized and further dispersed by repeated mechanical action and are potential sources for generating airborne asbestos fibers.
- Containers (bag, drums, wrapped components) should be labeled with the following warning: DANGER - CONTAINS ASBESTOS FIBERS - AVOID CREATING DUST - CANCER AND LUNG DISEASE HAZARD.
- Store material in a secure area until it can be taken to a landfill. Materials should be transported in a way that keeps them from leaking, spilling or blowing off thetransporting vehicle.
- You may obtain written approval for disposal by writing to the Asbestos Section, Bureau of Air Quality, S.C. DHEC, 2600 Bull Street, Columbia, SC 29201. State the address of the residence from which the material was removed, a brief description (for example, cement-like tiles, asphaltic shingles, etc.), the volume of waste in cubic yards or the area in square feet of the material removed, and the name and location of the landfill to be used. Contact the landfill directly to ensure it will accept the material. If you do not know of a landfill, contact our office at (803) 898-4123 for assistance.
- DO NOT BURN any asbestos-containing or asbestos-contaminated debris.
For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.