Question 7
Asbestos substitutes: Non-asbestos fibrous materials are used extensively, and are often proposed as substitutes for asbestos. In which areas of application are these materials used? Is there evidence available indicating biological activity of non-asbestos fibrous materials?
Answer:
Non-Asbestos fibrous materials, both man-made and extracted from natural deposits, are used and/or proposed as substitutes for asbestos. In industrialized countries, they can be found in practically all the major areas of applications of asbestos.
There are wide variations in competitiveness according to price, availability, technical performance, ease of handling and mixing, compatibility with other materials in composites, durability, etc.
There is no single fibrous alternative that could replace asbestos in all of its many varied applications. On the other hand, some fibrous materials are really not alternatives for asbestos, as they are used in areas where asbestos cannot be used (example: very high temperature refractory materials).
Compared to asbestos, evidence of biological activity of non-asbestos fibrous materials has been reported only recently. Except for a very limited number of materials (example: mineral wools), epidemiological scrutiny has yet to be undertaken in order to substantiate possible human health hazards.
On the other hand, recently published results from cell, tissue and animal experimentation indicate that all the materials reviewed in this section display some degree of biological activity.
These results suggest that their widespread production and use should be governed by appropriate monitoring and control of dust exposure, especially so for materials which are long and thin and which display long "in vivo" durability.
<< Back to index
Question 8 >>
References for Question 7:
U.S. Dept. Of Labor (OSHA) Synthetic Mineral Fibers: Hazard Description:
The American Occupational Safety and Health Administration (OSHA) has declared that glass fibres are "reasonably anticipated to be a carcinogen". The OSHA report states that "Several epidemiological studies have demonstrated statistically significant elevations in the risk of lung cancer and other respiratory system cancers among workers employed in fibrous glass and mineral wool manufacturing facilities".
International Agency for Research on Cancer (IARC) 1988. Man-Made Mineral Fibers: In IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man, 43:39-171, Lyon, France, WHO.
The WHO's IARC has classified glasswool, rockwool, slagwool and refractory ceramic fibres as "possibly carcinogenic to humans."
INSERM (French medical research council) Expert Council, Health effects of Substitute Fibres, Paris, June 1998: Quote from the Executive Summary:
Given the present uncertainties concerning the effects of asbestos substitute fibres in humans, it is important to ensure that exposure levels in users of products containing asbestos substitute fibres are as low as possible.
Looking at the conclusions of the various chapters in the report, questions recur about the possibility of risk involving rock wool and ceramic fibres in particular.
Once again, there is little or no sound toxicological data for materials such as cellulose (whose proinflammatory nature is known) and polyvinyl alcohol fibres which are in widespread use today.
