From Asbestos to Chrysotile
Current asbestos products are as different from the old ones as night and day. Today, only one type of asbestos is offered: 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: controlled use = safety
Chrysotile is a less dusty material and is more easily eliminated from the human body than amphiboles. The manufacture and use of modern products are safe as demonstrated by studies of workers exposed to much higher dust levels than in today's controlled factories which show no excess lung cancer or mesothelioma (cancer of the pleura).
There is more scientific evidence showing that asbestos-induced lung cancer, like fibrosis (asbestosis), is a threshold phenomenon. Moreover, studies 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. Mesotheliomas linked to exposure to asbestos are associated with amphibole fibres.
It is now known that in modern chrysotile manufacturing plants, at today's dust levels (0,5 to 1,0 fibres per mililitre) 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 (portland cement, water) 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 - Oxford, 1989), 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.
Why the controversy?
The real problem: old, poorly controlled products
Alarming reports of the rise in diseases linked to asbestos, combined with concern over the presence of asbestos insulation in buildings, have triggered intense controversy in Europe, especially in northern countries which were heavy users of friable asbestos insulation.
Because of the latency period between massive exposure and the appearance of diseases, it will take many more years before we see the health benefits of the prohibition of amphiboles and friable asbestos products which began in the 70's and of 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 air (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 when in good condition, these materials do not pose a health problem to the occupants.
However, management programmes, which 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 receive intensive 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 and workers. Hasty elimination of asbestos insulation considerably increases the probability that controls will not be adequately enforced, thus allowing excessive airborne asbestos dust and presenting a high 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 for chrysotile, few countries have introduced appropriate regulations for these substitute materials.
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 prohibiting the use of amphibole asbestos fibres and friable asbestos products. Conversely, chrysotile and its non-friable products, such as chrysotile-cement, can be used safely when 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.