Asbestos

Mg3Si2O5(OH)4

 

• Asbestos is a set of six naturally occurring silicate minerals: chrysotile, amosite, crocidolite, tremolite, anthophyllite and actinolite. They are more commonly known by their colours such as 'blue asbestos', 'white asbestos', 'brown asbestos' etc.

• All the asbestos minerals are characterized by their long, thin fibrous crystals.

• Chrysotile, a polymorph of the mineral serpentine, is the best-known type and makes up about about 95 percent of all asbestos in commercial use. It is extracted from the serpentine rock through crushing and blowing. Only fibres of 10mm+ are used for spinning into yarn ('white' asbestos'); shorter fibres are included in the manufacture of fibre cement products.

 

Properties

Asbestos is cheap, durable, flexible and acts naturally as an insulating and fireproofing agent.

 

History of use

The material's use was first made popular as a construction ingredient during the industrial revolution. From 1868, Italy, Canada, and nations around the world began operating massive mines to meet a burgeoning demand for the mineral. Manufacturers used the majority of the output from these mines to produce construction materials.

Following the highlighting of health concerns, the production of asbestos started to decline in the late 20th century until the new developing economies such as India, China and Brazil took off. From a leveling-out in 1999 at 1.8M tonnes, production has increased to more than 2M tonnes per year.

Most non-Western developing countries continue to use asbestos. The largest markets include China and India. It has been reported that Indian government officials support the asbestos industry because many of them state publicly that the mineral is not toxic, or at least not toxic under certain levels of exposure. The construction industry in India continues to use asbestos products in housing, and in industrial and commercial buildings – guaranteeing a health crisis in years to come.

 

Asbestos factory, Ahmedabad, India

Asbestos mining and products in the 1950s

 

Building components commonly containing asbestos

The list includes: Asbestos cement piping; asbestos cement roof slates; corrugated roofing; low density insulating board; plaster; vinyl floor tiles; adhesives; fire proofing and prevention materials; ceiling tiles; textured paint; door gaskets to older boilers and stoves; etc.

 

 

Current producers of asbestos

The Russian Federation produces around half of the world's output followed by China, Brazil and Kazakhstan. Mining in the 'West' has gradually ceased.

 

Discovering the threat to health

The identification of health risks can be traced back to at least Roman times. More recently, suspected asbestos-related conditions have a history of reporting from the late 19th century onwards.

Verified reports of the harmful effects of asbestos accelerated concern during the 1970s. Research found that prolonged inhalation of some forms of the tiny fibres can result in a life-threatening lung conditions. Once these health risks were confirmed, regulatory bodies in most developed countries began placing tight restrictions on, or terminating workers' exposure to asbestos in industry.

 

 

Exposure and related health conditions

In general, exposure only occurs when the asbestos-containing material is disturbed or damaged in some way to release particles and fibres into the air. In the UK where the use of asbestos in new work is banned, the usual route to exposure is through building demolition.

There is no 'safe' level of asbestos exposure for any type of asbestos. Asbestos exposures as short in duration as a few days have caused mesothelioma in humans. Every occupational exposure to asbestos can cause injury or disease; every occupational exposure to asbestos contributes to the risk of getting an asbestos related disease.1

The four major health effects associated with asbestos exposure are:     

• lung cancer    

• mesothelioma, a rare form of cancer that is found in the thin lining of the lung, chest and the abdomen and heart    

• asbestosis, a serious progressive, long-term, non-cancer disease of the lungs (currently increasing annually in the UK)     

• Non-malignant pleural disease, a diffuse pleural thickening and pleural plaques) 

 

Continuing prevalence

• In 2011 it was reported that over 50% of UK houses still contained asbestos, despite the 1985 ban on asbestos products. (see the Guardian, 1/5/2011, http://bit.ly/ZZAY8i )

• Exposure to asbestos is the biggest single cause of work-related deaths in the UK. Around 4,000 people a year die from asbestos-related disease.2

 

Regulation in the UK

Blue and brown asbestos materials were banned outright in 1985 while the import, sale and second hand reuse of white asbestos was outlawed in 1999. The 2012 Control of Asbestos Regulations state 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, e.g. construction companies, whose operatives may come into contact with asbestos must also provide annual asbestos training to their workers.3

 

References

1  US Department of Labor

2  NHS Choices

3  Wikipedia

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