FAQs

Is chrysotile dangerous to workers and how?

Dusts or airborne fibres including glass fibre, synthetic fibre, chrysotile fibre, stone dust, gasoline fume, exhaust fume, all are dangerous, if workers inhale and are exposed to them for a long period of time. However, the processing of chrysotile fibre as a raw material in manufacturing factories is properly controlled and thus, poses no risks to workers. Once the fibres are covered by cementous slurry, they are locked-in permanently and cannot escape.

Are workmen installing or fixing asbestos cement roof at risk of exposure to chrysotile?

Typical test results of air sampling show that fibre concentration is around 0.07 fibre/cc during cutting and installation of chrysotile cement roofing sheets. This is far below the level of 0.5 fibre/cc envisaged. There will be no risk for workmen or carpenters if they follow properly recommended work practices while installing or fixing roofing sheets.

Is there any evidence of workers who suffer from asbestos related diseases in Thai factories?

Thai manufacturers follow recommendations from the Ministry of Industry and Ministry of Public Health. They provide health check-up and lung x-ray for all employees annually. There is no evidence regarding the disease up to date.

Is there any new production or technology that is friendly to the environment?

Most manufacturers have invested in large and efficient dust control equipment in the factories for the safety of operators and workers.

Asbestos in friction materials: What is the contribution to the general environment resulting from the use of asbestos in friction materials?

Asbestos has been an essential component of automotive friction materials for more than 70 years; and only chrysotile asbestos is used for industrial purpose. Its typical proportion ranges from 25% to 65% by weight. Chrysotile enforces strength, flexibility, heat resistance to brake linings, in addition to friction and wear properties.

Comprehensive investigations conducted with the support of the U.S. Environmental Protection Agency (EPA) have shown that on an average, more than 99.7% of the asbestos emitted as a result of wear and abrasion has been converted into other products such as forsterite, a material which has been found non-carcinogenic in animals. Furthermore, it has been determined that such asbestos (less than1%) as may be present in wear debris consists predominantly of very short (0.3 u) fibres. 

Thus, the emission of free fibres resulting from brake lining wear is a negligible health factor in urban air pollution. Indeed, recent estimates of air concentration of asbestos resulting from vehicular brakes in large U.S. cities ranges from 0.051 ng/m3(Rochester, NY) to 0.258 ng/m3 (Los Angeles, CA). If a conversion factor of 30 fibres measured optically per nanogram of asbestos is used, the measured values in Los Angeles would be 7.74f/M3 or 0.000007 f/cc.

Is it dangerous to live or work under chrysotile cement roof?

There is no risk, whatsoever, for people who live or work under chrysotile cement roof. Chrysotile fibres are locked-in and bound with cement. It is not possible for the fibres to escape from the products into the ambient air.

What is the risk associated with the presence of asbestos at concentration levels found in the general environmental air?

Asbestos fibres have been present in the general environmental air long before human’s exploitation of the mineral. This is due to the natural erosion from geological formations which are quite common across the world. The total amount of asbestos emitted from natural sources is much greater than that emitted from industrial sources.

Is the public at risk due to the weathering of chrysotile cement products?

Because of inherent properties of chrysotile fibre and cement, chrysotile cement sheets do not decay or rot. They do not crumble despite continued exposure to environmental elements or age. There is no evidence that people living under chrysotile cement roof, or the general public living around asbestos cement-roofed buildings or factories producing asbestos cement products have been specifically affected in any manner.

In fact, studies have concluded that the increase in chrysotile dust concentration in near vicinity of chrysotile cement rooftop is so insignificant that it cannot be detected by an electron microscope.

Does exposure to one single asbestos fibre lead to death?

Conducting an experiment to test this proposition is not feasible. It is virtually impossible to challenge cells, tissues or whole animals to one single fibre due to the ubiquity of asbestos fibres. One milligram of asbestos alone may contain several hundred million respirable fibres. Furthermore, experimental protocols call for a minimum dose of several hundred thousands of fibres in order to induce observable effects. 

On the other hand, he following facts may help to reach a sensible judgment:

  • In every 60 seconds, the lungs of a normal person handle some 10 liters of air.
  • Around the world, in a given environment, e.g. the air in cities and rural areas, fibre concentration is approximately 1 fibre per liter (possibly a little more or a little less, depending on circumstances of location, weather conditions, etc.).
  • From the above observations, it can be concluded that 14,400 liters of air (10 liters x 60 min. x 24 hrs), each one containing 1fibre, transit thorough the lungs of a "normal" non-occupationally exposed person daily.
Asbestos in water: Does the use of asbestos-cement pipes contribute significantly to the presence of asbestos in water? Is there a risk associated with the presence of asbestos in drinking water?

The use of asbestos-cement (A/C) pipes is dated back to the early 1920s. It is estimated that by the end of the 1980s, nearly 3 million kilometres of pipes would have been laid worldwide to transfer potable water.

Highly aggressive waters may attack the cement matrix, and consequently lead to the release of fibres into the water circulation through the pipes. A/C pipes are not recommended for use under such highly corrosive conditions, unless protected with specially designed internal protective lining.

The results of most studies published so far indicate that the source waters already contain asbestos fibres (mostly shorter than 1 u in length) before passing through the A/C pipe systems, often in numbers reaching several millions per liter. It is generally agreed that A/C pipes do not appreciably raise the asbestos fibre content of water, and that the quantities found are within those which occur naturally.

As to the risk of health resulting from the presence of asbestos in potable water, results of several years of laboratory investigation in animals fed for their entire lifespan with very large (several billions of fibres every day) quantities of asbestos incorporated into their diet have consistently failed to indicated any raised incidence of gastrointestinal tumours, or of any other pathological changes in the gastrointestinal tract. Moreover, epidemiological studies on human health effects related to asbestos levels in drinking water have failed to indicate any increased risk of alimentary tract tumours following the direct ingestion of asbestos fibres. 

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