Find out how to manage and dispose of asbestos-containing waste without causing harm to the environment and human health.
What is Asbestos?
Asbestos is a generic term used to describe a family of naturally occurring compounds called hydrated silicates that have a fibrous nature. Asbestos fiber is chemically inert, heat resistant, and mechanically strong. Because of its fibrous nature, it can be used as reinforcement for cement and plastics and even woven into fabrics.
Asbestos was used widely until the 1960s, when it became established beyond any doubt that the fibers represented a danger to health. Since then, most countries have introduced regulations to control or prohibit the use of asbestos, and it has been used in fewer and fewer applications. (See Asbestos regulations in different countries) This means that asbestos waste will normally be generated from refurbishment or demolition projects.
Types of Asbestos
Several types of asbestos exist, including actinolite, tremolite, and anthophyllite. However, only three have been widely used and are considered below:
White Asbestos (Chrysotile)
White asbestos was the most commonly used type of asbestos. It is resistant to alkaline attack and especially common as reinforcing material in asbestos-cement, roof panels, fire curtains, blankets, and friction products. Chrysotile is white to greenish-grey depending on the impurities present with flexible wavy fibers of 12 to 40 mm in length.
Blue Asbestos (Crocidolite)
This type of asbestos is highly resistant to mineral acid attack and was used extensively in chemical and gas works. It was also the favored material for sprayed thermal and acoustic insulation on boilers and pipe work. Blue asbestos is no longer produced. Crocidolite is lavender-grey to bluish-green in color with fibers that are thin, straight, and sharp.
Brown Asbestos (Amosite)
Brown asbestos has superior heat resistance and is used in fire-resistant insulation boards. Amosite is grey-brown in color and has long fibers that are harsh and too brittle for weaving.
Hazardous Properties and Health Effects of Asbestos
Asbestos is potentially toxic and carcinogenic. Although long-term exposure to all types of asbestos is hazardous, blue asbestos is the most harmful. The key exposure routes are listed below.
Inhalation
The inhalation of asbestos results in fibers or dust being deposited in the lungs. This can cause:
- Asbestosis (scarring of lung tissue);
- Mesothelioma (malignant tumor in chest wall or abdominal cavity);
- Bronchial carcinoma (lung cancer).
Ingestion
The ingestion of asbestos fibers via drinking water (contaminated from asbestos-cement pipes, asbestos industry effluent, or natural sources) is thought to be harmful.
Dermal (Skin) Contact
Corns or warts may develop if asbestos is allowed to come into direct contact with the skin. They have never been known to become malignant.
If you are worried about asbestos exposure, please read 'How to Stop Worrying About Asbestos'.
How to Manage Asbestos Waste?
Most asbestos waste will be generated from refurbishment or demolition projects. An experienced contractor should be appointed who will ensure that the asbestos is removed without risk to human health and the release of fibers into the environment. As a minimum, a documented risk assessment and a safe system of work should be developed.
 |
| Asbestos Containing Material Waste |
Whenever possible, the release of asbestos dust should be minimized by keeping materials intact. If it is necessary to employ drilling and cutting operations, hand tools should be used as they create less dust than power tools.
Asbestos waste should be segregated from other types of waste to prevent cross-contamination. Fibrous asbestos waste or dust should be segregated at the point of arising from any other waste, including asbestos cement or other bonded asbestos waste, as this represents the greatest hazard. However, all asbestos waste should be classified and treated as hazardous (carcinogenic), irrespective of its capacity to release fibers.
If it is necessary to manage the disposal of materials that may be asbestos but whose precise composition is unknown, they should be treated as asbestos waste.
Materials that may have been exposed to asbestos fibers, such as personal protective equipment and cleaning equipment, including clothing, face masks, vacuum bags, and cloths, should also be treated as asbestos waste.
Asbestos waste should be placed in suitable containers. Normally strong (500 gauge) color-coded polythene bags (double bagged) or polythene sheeting for larger items is used. The containers should be sealed securely.
Air should be excluded from the bags as far as possible before sealing. Whenever there is the potential for sharp or heavy items to pierce the plastic, a more rigid container should be used. Each container should be clearly labeled according to local requirements and, at minimum, labeled as “asbestos waste.”
If it is necessary to sample the asbestos waste after it has been collected, it should be kept damp to prevent the release of fibers, and appropriate Personal Protective Equipment (PPE) should be worn. A water hose and nozzle that produces a fine low-pressure spray or mist to wet the waste can be used to dampen asbestos waste, but care should be taken to collect contaminated run-off water.
Collection and Transport of Asbestos Waste
Asbestos waste should be transported in a hard-sided bin or vehicle to prevent the release of fibers and dust during transport. Whenever possible, the vehicle should proceed directly to the point of final disposal. Following the disposal, the vehicle should be safely cleaned of any extraneous fibers and dust before undertaking other duties or leaving the point of final disposal.
A form that documents the transfer of waste from the waste producer to the point of final disposal should accompany the waste.
Treatment and Disposal of Asbestos Waste
Whenever possible, all asbestos waste should be disposed of either in landfills equipped with liners and leachate treatment systems or in the landfills used for hazardous waste.
If a suitable landfill cannot be found, it may be necessary for waste to be stored securely on site until a suitable facility becomes available. In such circumstances, the waste should be placed in appropriate containers. The containers should be sealed securely, and each container should be labeled as “asbestos waste.” The storage area should be made secure to prevent accidental mechanical damage, and personal access to the storage area should be controlled.
The landfilling of asbestos requires particular care to ensure that fibers are not released into the atmosphere or surrounding watercourses.
Unbonded and slurried asbestos wastes (the latter is usually generated from washings and damping down) should be deposited in a contained bay by forming a compacted bund of other, preferably incombustible waste. Asbestos slurry should then be covered with dry absorbent wastes that will encapsulate it after disposal.
Unbonded asbestos should be moistened during loading and unloading, still packaged, and immediately covered with either a 20 to 25 cm layer of consolidated earth or a 1.5 to a 2-meter layer of non-asbestos waste that does not contain sharper heavy waste that could rupture the bags.
Where necessary, a water bowser may be placed above the disposal area to suppress any release of fibers during disposal. Bonded asbestos should be covered as soon as practicable and certainly by the end of the working day. The location and depth of burial should be recorded, and procedures put in place to ensure that it is not re-excavated (e.g., when drilling gas wells). Operatives should wear appropriate PPE. Asbestos inputs to each site or cell should be limited to times when appropriate cover material and staff are available.
Because of the importance of recording the location of fibrous asbestos deposits, asbestos waste should be placed at the foot of the working face and its location recorded.
Care should be taken to ensure that asbestos waste is adequately covered with other wastes before it is compacted and its sealed containment compromised. It is recommended that asbestos should not be landfilled within 2 m of the perimeter or final cap to reduce the possibility of the general public being exposed to landfill fibers.
Hard or bonded asbestos should not be used for the construction or repair of site access roads or vehicle parks as it may release asbestos fibers.
It is recognized that some disposal methods rely on encapsulating fibrous asbestos into a cement mix. Such processes prevent the subsequent release of fibers but involve additional handling, transportation, and processing and are therefore not recommended. Acid and thermal treatment systems have also been developed, but these are unlikely to be commercially or technically viable in the near future.