Modern asbestos products are as different from the old ones as night and day. Today, only one type of asbestos is used: chrysotile. In addition, the industry now only markets dense and non-friable materials in which the chrysotile fibre is encapsulated in a matrix of either cement or resin. These modern products include chrysotile-cement building materials, friction materials, gaskets and certain plastics.
The old products, principally low-density insulation materials, were very dusty and crumbled under hand pressure. Unlike today's products, they often contained amphibole fibres (crocidolite and amosite).
Chrysotile: control = safety
Chrysotile is a less dusty material and is more easily eliminated from the human body than amphiboles. The claim that the manufacture and use of modern products are safe stems from the fact that studies of workers exposed to much higher dust levels than in today¹s controlled factories show no excess lung cancer or mesothelioma (cancer of the pleura).
This observation was in fact recently explained by the Health & Safety Executive (HSE) of Great Britain, which stated that asbestos-induced lung cancer, like fibrosis (asbestosis), is a threshold phenomenon. Moreover, the HSE confirms that very few cases of mesothelioma have been reliably attributed to chrysotile, despite the many thousands of workers who in the past, have had massive and prolonged exposures.
It is now known that in modern chrysotile manufacturing plants, at today's dust levels (500 to 1,000 fibres per litre) the risks, if any, are so low as to be undetectable. This is what is called a practical threshold.
Chrysotile-cement: a safe, high-quality product
90% of the world production of chrysotile is used in the manufacture of chrysotile-cement, in the form of pipes, sheets and shingles. These products are used in some sixty industrialized and developing countries.
Chrysotile-cement is valued principally for its excellent cost effectiveness and durability. Manufacture of this material requires the import of only small quantities of fibre, the other raw materials being easily available locally. Moreover, the manufacturing technology requires little investment and consumes less energy than production methods for competing products.
According to a group of experts convened by the World Health Organization (WHO), chrysotile-cement products do not present risks of any significance to public health or the environment. Moreover, workers in this industry, whether employed in the manufacture, installation or removal of materials, are not exposed to any detectable risk when effective prevention and control measures are applied.
All asbestos-related diseases have a long latency period, which means that it takes 20 to 40 years for the first symptoms to show up. Given the poor work conditions of the past, the widespread use of amphiboles up until the 70s, and this long latency period, it is not surprising that new cases of asbestos-related disease continue to be observed. Workers in the ship building and construction industries who installed friable asbestos insulation materials have been the most severely affected. Many of these workers were exposed to dust levels 100 to 200 times higher than those permitted by current standards.
It will take many more years before we see the health benefits of the banning of amphiboles and friable asbestos products which began in the 70s and the regulations which now impose strict factory controls.
Do in-place friable asbestos insulation materials
pose a threat to public health?
Numerous studies of buildings containing friable asbestos insulation materials demonstrate that air-borne dust levels within these buildings are not significantly different than in outside ambient (0.1 to 1 fibres/litre). As a result, the U.S. Environmental Protection Agency (EPA) and the government authorities of several countries have therefore concluded that if in good condition, these materials do not pose a health problem to the occupants.
However, management programmes, which would include inspections and corrective measures whenever necessary, are recommended for buildings containing asbestos insulation materials. Moreover, all maintenance workers must have access to adequate safety equipment and benefit from training and information programs to ensure correct work practices are followed when handling these materials. Removal of asbestos insulation should be considered a measure of last resort, and undertaken only when the material is beyond repair or at the time of major renovation work or building demolition.
Asbestos removal = danger
Banning chrysotile-cement will not resolve the problem of friable insulation in buildings. It may, however, contribute to unwarranted public paranoia and a rush to initiate unnecessary and potentially dangerous removal work.
Asbestos removal is a very costly operation which must be conducted by highly specialized contractors. Hasty elimination of asbestos insulation considerably increases the probability that controls will not be adequately enforced, thus presenting a source of risk not only for the workers, but for building occupants as well.
Moreover, removal can create a new danger. Replacement products contain natural or synthetic fibres that can be hazardous as well. However, unlike chrysotile, few countries have introduced appropriate regulations for these substitute materials.
Controlled use
While industrial development contributes to the well-being of society, it has also brought us numerous potentially hazardous products which we use daily and which are far more dangerous than chrysotile. In order to safely benefit from these products, we introduce standards and develop technologies and work methods which constitute what we call controlled use. The principle dictates that when the risks associated with a product cannot be controlled, its use should be discontinued; this was the rationale for banning amphibole asbestos fibres and friable asbestos products. Conversely, chrysotile and its non-friable products, such as chrysotile-cement, can be used in complete safety if properly controlled throughout the product life-cycle. This is the position taken by the governments of Canada and Québec, regarding not only chrysotile asbestos, but all minerals and metals.