ASBESTOS INFORMATION

There has been a lot of debate, discussion and lobbying on the issue of asbestos, its mining and use. Local media has carried reports on the issue, a number of them just downloaded from Reuters and other cable news networks and pasted in their publications. What has become apparent is that there is a lot of ignorance and misinformation on the subject of asbestos, the hazards and risks associated with its mining and use. Unfortunately those in the know have taken long to de-mystify the mineral and lay the facts on the ground for all to see and participate in interactive discussion and debate on the issue from an informed position.

Asbestos and Health
Turnall as a responsible corporate citizen has taken the initiative to educate its stakeholders on the asbestos issues. Our main aim is to establish a mutual understanding with the different stakeholders, with the correct information having been disseminated. It is also a reaction to the anti-asbestos lobby being spread throughout the world. Turnall promotes the dissemination of information and education of all concerned with regard to health hazards due to exposure to asbestos and to methods of prevention and control.

What is asbestos?

All durable fibres that are respirable can be dangerous. Respirable fibres (too small for the eye to see) are able to escape the body's defence mechanisms and enter the small passages in the lungs where the oxygen exchange takes place. Because asbestos is very durable, the fibres resist the body's efforts to dissolve them. Over many years a build of millions of respirable asbestos fibres can cause scarring of the lung tissue (asbestosis), lung cancer or, in very rare cases, mesothelioma, and a cancer of the lining of the stomach or lungs.All asbestos-related diseases have latency periods of between 10 and 45 years. Most current cases are as a result of heavy exposure in mining areas or factories more than 20 years ago.
The objective therefore is to highlight the other side of the story that the majority of people have not heard concerning the asbestos issue – all that has been coming through is the negative side of the asbestos fibre. The anti-asbestos lobbyists have taken a deliberate position to generalize information on the mineral and have done that successfully by referring to the asbestos family of minerals so as to give foundation to their assertion that asbestos fibre is carcinogenic. By so doing they have been able to create a negative, yet false perception towards asbestos and asbestos-cement products.
So, how much do you know about asbestos, what is your perception towards asbestos-cement products? How much do you know about the risks and hazards associated with the mining, handling, storage and working with asbestos fibre? This manuscript will give you the latest scientific research findings and factual information on this wonder mineral.

Types of asbestos

Chrysotile, or white asbestos is obtained from Canadian and Zimbabwean serpentine rocks. Serpentine rocks are those with curled fibres. Amphiboles have straight, needle-like fibres. It is less friable (and therefore less likely to be inhaled) than the other types and is the type most often used industrially. Chrysotile should not be confused with chrysolite, a synonym of olivine. There is some evidence that this form of asbestos is not actually harmful when inhaled.One formula given for Chrysotile is Na2Fe2+3Fe3+2Si8O22(OH)2.
Amosite, CAS No. 12172-73-5, also known as Grunerite or brown asbestos, is an amphibole from South Africa, named as an acronym from Asbestos Mines of South Africa. One formula given for Amosite is Fe7Si8O22(OH)2.
Crocidolite, or blue asbestos, CAS No. 12001-28-4, is an amphibole from Africa and Australia. It is the fibrous form of riebeckite. Blue asbestos is commonly thought of as the most dangerous type of asbestos (see above and below). One formula given for Crocidolite is Na2Fe2+3Fe3+2Si8O22(OH)2.
The amphiboles, in their fibrous form, are friable and therefore the most carcinogenic, although they also exist in safer non-fibrous forms. Asbestos with particularly fine fibers is also referred to as "amianthus".
Other asbestos minerals, such as tremolite, CAS No. 77536-68-6, Ca2Mg5Si8O22(OH)2; actinolite (or smaragdite), CAS No. 77536-66-4, Ca2(Mg, Fe)5Si8O22(OH)2; and anthophyllite, CAS No. 77536-67-5, (Mg, Fe)7Si8O22(OH)2; are less-used industrially but can still be found in a variety of construction materials and insulations and occur in a few consumer products, such as talcum powders and vermiculite.

Amphibole group

Amosite and crocidolite were used in many products until the early 1980s. The use of all types of asbestos in the amphibole group was banned in the mid-1980s. These products were mainly:

• asbestos cement sheets and pipes for construction, casing for water and electrical/telecommunication services
• thermal and chemical insulation (i.e., fire rated doors, limpet spray, lagging and gaskets)

What sort of exposure is necessary to cause disease?

Individual susceptibility varies considerably but it is generally agreed that it would take 25 years of exposure of 1 fibre per millilitre (the legal exposure limit in Zimbabwe) to cause asbestosis - and about four times more to cause lung cancer.
Heavy exposure is only likely to occur in an occupational environment. In the very unlikely event a worker was exposed to the Exposure Limit for 12 hours a day, it would take up to 50 years to have sufficient fibre loading to cause disease. Asbestos fibre levels at Turnall workplaces are well below half the S.A. Exposure Limit and do not exceed 0.2f/ml.
We are not sure what exposure is required to cause mesothelioma but we are reasonably certain that this disease is caused by blue and brown asbestos only. Turnall has used only white asbestos.

What about exposure in the general environment or in buildings?
Asbestos is the most common mineral in the crust of the earth and therefore generally presents in the air while we breathe. All of us have some fibres in our lungs but it requires heavy exposure over many years, probably in an occupational environment, to cause disease.
Asbestos fibre levels in buildings (with or without asbestos-cement building materials) are similar to those found outdoors.
There has been a great deal of confusion arising from publicity given to asbestos removal programs overseas. These refer to the removal of loose and friable asbestos insulation materials which were commonly used for temperature control and fire protection, and not to asbestos cement. There is now concern that the removal programmes are resulting in the unnecessary release of respirable fibres and encapsulation of insulation materials is preferred. No government has called for the removal of asbestos cement materials from buildings.
What about asbestos released into water from asbestos-cement pipes?
All natural water has some asbestos in it. In some countries this can be millions of fibres per litre of water. Medical science is agreed that fibres ingested into the stomach do not cause disease. The World Health Organisation has recommended the use of AC pipes to convey drinking water.

Is there a risk to building contractors who cut AC materials?
Although there are very few cases of asbestos-related disease recorded among construction workers in South Africa, it must be recognised that the risk of disease increases with exposure to respirable asbestos fibres. It therefore makes sense for specifiers to avoid on-site cutting by ordering material to size. If some cutting must be done on site, construction workers should use manual tools (which do not produce respirable dust) or dust-free power tools supplied by the industry. They should take basic precautions such as working outdoors and wetting the cutting surface. Ideally, an industrial vaacum cleaner with a high efficiency filter should be used to collect asbestos-cement dust, which must be safely disposed of.

Uses

Serpentine group
Chrysotile is the form of asbestos from the serpentine group that is used commercially.
In Zimbabwe, China, Brazil, India, Canada, Russia and the United States, chrysotile is the most commonly used type of asbestos. Chrysotile is often present in a wide variety of materials, including but not limited to:

• sheetrock taping
• mud and texture coats
• vinyl floor tiles, sheeting, adhesives and ceiling tiles
• plasters and stuccos
• roofing tars, felts, and shingles
• "transite" panels, siding, countertops, and pipes
• accoustical ceilings
• fireproofing
• putty
• caulk
• gaskets
• brake pads and shoes
• clutch plates

What do I do if I meet someone who will not accept or challenges what I say?
Refer all difficult questions to the National Chrysotile Task Force Secretariat on 263-4-755474/9 or Turnall WCP Manager T Jena on 0712 439 902.
In fact it would be useful to report the nature of all such enquiries so as to provide a useful measure of public opinion and concerns.