What is asbestos?

Posted: 19th Mar 15 11:37 AM

Asbestos is a naturally occurring fibrous material which has been regularly used from the end of the 19th century until the late 1990s in both manufacturing and construction.

Thanks to its versatile properties, such as its fire-resistance and the fact that it is the only known mineral that can be woven into a thread, it had been known as the ‘magic-mineral’.

Asbestos has been found to be a hazardous substance and needs to be handled with care. When asbestos is disturbed it releases fibres as well as a visible dust which can present serious health risks when breathed in. It can be fatal.

Types of asbestos

There are 6 mineral types that are defined by the Environmental Protection Agency as ‘asbestos’, and these are split into 2 main classes of asbestos.

Serpentine – Serpentine class fibres are curly in appearance. There is only one member in this class of asbestos, called Chrysotile.

Chrysotile asbestos is obtained from serpentinite rocks, which are found commonly throughout the world. Chrysotile appears under the microscope as a white fibre. This type of asbestos has been used more than any other, as it is more flexible than any of the Amphibole class asbestos and can be spun and woven into a fabric. Its most common use has been in corrugated asbestos cement roof sheets typically used for outbuildings, warehouses and garages. It may also be found in sheets or panels used for ceilings and sometimes for walls and floors. Chrysotile has been a component in joint compounds and some wall plaster. Numerous other items have been made containing chrysotile, including brake linings, fire barriers in fuse boxes, pipe insulation, floor tiles, and gaskets for high temperature equipment.

Amphibole – Amphibole class fibres are needle-like in form. The remaining 5 types of asbestos fall into this category, including Crocidolite, Amosite, Tremosite, Anthophyllite and Actinolite.

Crocidolite asbestos is the fibrous form of the amphibole riebeckite. Crocidolite is seen under the microscope as a blue fibre. Often referred to as blue asbestos, it is considered the most hazardous. In 1964, Dr Christopher Wagner discovered an association between blue asbestos and the asbestos related cancer mesothelioma. Unbelievably, Bolivian-mined crocidolite was used in Kent Micronite cigarette filters in the 1950s. Blue asbestos was also formerly used in early gas masks.

Amosite asbestos, often referred to as brown asbestos, is seen under a microscope as a grey-white fibre. It is found most frequently in materials used as fire retardants in thermal insulation products, asbestos insulation and ceiling tiles.

Tremolite, Anthophyllite and Actinolite asbestos are used less commonly industrially, but can still be found in a variety of construction and insulation materials, and have even been reported to be found in a number of consumer products in the past.

Early use

Asbestos use in human culture dates back to at least 4,500 years ago, as evidence shows that inhabitants of a region in East Finland used asbestos to strengthen earthenware pots and utensils with the asbestos mineral Anthophyllite.

The word ‘asbestos’ itself originates from the ancient Greek ἄσβεστος, which means ‘unquenchable’ or ‘inextinguishable’.

Marco Polo recounts having been shown, in a place he called ‘Ghinghin talas’, “a good vein from which the cloth we call of salamander, which cannot be burnt if it is thrown into the fire, is made…”

The early Romans used napkins and tablecloths made from asbestos, and tossed them into fires to be cleaned. They marvelled that they came out whiter than before.

Industrial use

The large scale asbestos industry began in the mid-19th century. Attempts at creating an asbestos-based paper and cloth began in Italy in the 1850s, but these were unsuccessful in creating a market for those products.

The use of asbestos increased at the end of the 19th century, when its diverse applications included fire-proof coatings, concrete, bricks, pipe insulation and various other uses, both industrial and commercial.

Unusual uses

Because of its varied properties, including its dust and fibre like appearance, asbestos has also been used in some quite unusual items.

Fake snow: back in the 1930s to 1950s, asbestos was used to make a fake snow product that was used as a Christmas decoration. Its heat-resistant properties meant it was a much lower fire risk than alternatives – and it was even used on the film set of ‘The Wizard of Oz’.

Filters: in the 1950s asbestos also appeared in the filters of some cigarettes and even early gas masks.

Toothpaste: perhaps most surprisingly, asbestos was an added ingredient in a brand of toothpaste – apparently due to the abrasive quality of its fibres.

Asbestos in construction

Asbestos was widely used throughout the construction industry in thousands of materials. Some are judged to be more dangerous than others because of the amount of asbestos within them and the material’s friable nature. Sprayed coatings, pipe insulation and asbestos insulating board (AIB) are thought to be the most dangerous due to their high content of asbestos and crumbly nature.

Widely known for its fireproofing abilities, asbestos was a common ingredient in insulating products. Manufacturers typically added asbestos to these products to make them stronger and fire-resistant. Spray-on insulation was one of the most widely used asbestos products in the construction industry.

Workers sprayed products such as Cafco D and Therm-O-Flake, which contained up to 35 percent chrysotile asbestos, on steel columns, aluminium sheets and other metal structures that needed to withstand high temperatures.

In buildings built before the 1999 banning of white asbestos in the UK, asbestos may still be present in some areas such as old bath panels, concrete water tanks and many other places. In 2011, it was reported that over 50% of all UK homes still contained asbestos.

Exposure to asbestos

People may be exposed to asbestos in their workplace, their communities, or even their homes. If products containing asbestos are disturbed, tiny asbestos fibres are released into the air. When asbestos fibres are breathed in, they may get trapped in the lungs and remain there for a long time. Over time, these fibres can accumulate and cause scarring and inflammation, which can affect breathing and lead to serious health problems.

Everyone is exposed to asbestos at some time during their life. Low levels of asbestos are present in the air, water, and soil. However, most people do not become ill from their exposure. People who become ill from asbestos are usually those who are exposed to it on a regular basis, most often in a job where they worked directly with the material or through substantial environmental contact.

Trades which were most at risk from coming into contact with asbestos include:

  • Labourers
  • Pipefitters
  • Plasterers
  • Carpenters
  • Demolition and wrecking crews
  • Insulation workers
  • Roofers
  • Tile setters
  • Ship builders

Because workers from various trades can share a single jobsite, it could only take one negligent worker to place many people at risk. Asbestos dust can spread around jobsites easily and expose people who never even handled asbestos directly. Even worse, workers could bring the dust home on their clothes, hair or tools, which could place their families at risk of secondary exposures, which can be just as deadly.

Asbestos related health effects

Individuals who have been exposed, or suspect they have been exposed, to asbestos fibres in their workplace, through the environment, or at home via a family contact should inform their doctor about their exposure history and whether or not they experience any symptoms. The symptoms of asbestos-related diseases may not become apparent for many decades after the exposure. It usually takes between 10 and 50 years for an individual to develop any symptoms of an asbestos related disease. It is particularly important to check with a doctor if any of the following symptoms develop:

  • Shortness of breath, wheezing, or hoarseness
  • A persistent cough that gets worse over time
  • Blood in the sputum (fluid) coughed up from the lungs
  • Pain or tightening in the chest
  • Difficulty swallowing
  • Swelling of the neck or face
  • Loss of appetite
  • Weight loss
  • Fatigue or anaemia

Known asbestos-related diseases

Diseases commonly associated with asbestos include:

Pleural plaques: a discrete fibrous or partially calcified thickened area on the lungs which can be seen on X-rays of individuals exposed to asbestos. Although pleural plaques themselves show no symptoms, in some patients this develops into pleural thickening.

Pleural thickening (or diffuse pleural thickening): similar to the above and can coexist with pleural plaques, pleural thickening covers a much larger section of the lungs. Usually there are no symptoms shown other than coughing and shortness of breath, but if left undiagnosed and untreated it can cause extensive lung impairment. You can read more about pleural thickening on our blog.

Asbestosis: a progressive fibrosis of the lungs of varying severity, progressing to bilateral fibrosis, is a honeycombing of the lungs on radiological view with symptoms including wheezing. You can read more about asbestosis on our blog.

Mesothelioma: mesothelioma is a type of lung cancer that most often starts in the lining of the lungs, but can also start in the abdomen. In its early stages, mesothelioma does not have many symptoms, whether it is in the chest or the abdomen. When symptoms do develop, they are often caused by the cancer growing and pressing on a nerve or another organ.

Symptoms of mesothelioma can include:

  • Pain in the lower back or the side of the chest
  • Shortness of breath
  • Sweating and high temperatures
  • A persistent cough
  • Losing more than 10% of your weight when not dieting
  • Difficulty swallowing
  • A hoarse or husky voice

Lung cancer: lung cancer is a malignant lung tumour characterised by uncontrolled cell growth in tissues of the lung. Tobacco smoking and asbestos have a synergistic effect on the formation of lung cancer. In smokers who worked with asbestos, the risk of lung cancer is increased considerably compared to the general population.

Modern regulations

Through the 1970s, asbestos was used to fireproof roofing and flooring, for heat insulation, and for a variety of other purposes. The material was used in fire-check partitioning and doors on North Sea oil production platforms and rigs.

During the mid-to-late 1980s, public health concern focused on potential asbestos fibre exposures of building occupants and workers in buildings with asbestos containing building materials and their risks of developing lung cancer or mesothelioma. As a consequence, the Health Effects Institute of Cambridge, America, formed a panel to evaluate the lifetime cancer risk of general building occupants as well as service workers.

In the United Kingdom, blue and brown asbestos materials were banned completely in 1985, while the import, sale and second hand use of white asbestos was outlawed in 1999. The 2012 Control of Asbestos Regulations states that owners of non-domestic buildings (e.g. factories and offices) have a ‘duty to manage’ asbestos on the premises by making themselves aware of its presence and ensuring the material does not deteriorate, removing it if necessary. Employers whose operatives may come into contact with asbestos must also provide annual asbestos training to their workers.

Further reading

For more information on asbestos and asbestos related conditions, please have a read through some of our previous articles:

What is asbestosis?

What is pleural thickening?

How to deal with the stress of being diagnosed with asbestosis

Asbestos in the workplace

Can five days of asbestos dust exposure make a contribution to the development of asbestosis?