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Are they really safe?

Chrysotile-free but not risk-free!

A simple equation has been circulating for a long time: asbestos-free = risk-free. Conventional wisdom was that all one had to do was replace asbestos fibers with other fibers, and the job was done. Industries and governments therefore avoided using asbestos in many products in favor of untested substitute fibers.

Toxicity and regulation of substitute fibers

Replacing chrysotile is a very complex operation. Evaluations of the risks and hazards of a good many other fibers are now clear enough that legislators are beginning to impose regulations to control these substitutes.

In 1993, a group of experts brought together by the World Health Organization (WHO) issued Environmental Health Criteria 151, stating that all respirable and biopersistentfibers must be tested to check their toxicity and carcinogenicity. In fact, recent studies have shown that many fibers used to replace asbestos in numerous products may be as hazardous or even more hazardous than chrysotile asbestos: this is notably the case for fiberglass, rock wools, refractory ceramic fibers and aramid fibers. In 1993, the International Program on Chemical Safety (IPCS) explicitly recommended that exposure to any respirable and durable fiber be controlled to the same extent as that required for asbestos until the data prove that lesser controls would be sufficient.

Germany classifies glass wools, rock wools and mineral wools as probable carcinogens. Several other countries are also moving in this direction and have introduced exposure standards and work methods for several fibers. However, to protect workers’ health effectively, any such regulation should encompass all fibers. In 1994, the European Commission announced a complete fiber review program, which should make it possible to establish a new classification based on carcinogenicity. Please see the chart of substitutes for a summary of scientific findings on the health effects of the main categories of substitute fibers.

Reliability and performance of substitute fibers in brakes

In addition to the health problems linked to their handling, many non-asbestos friction materials may have inferior physical and technical characteristics. Despite higher manufacturing costs than chrysotile-containing products, and despite years of technological research and development, substitute fiber-based friction products still pose performance problems for certain types of vehicles.

In the United States, every year exploding brake drums on heavy trucks cause numerous highway fatalities. Diagnoses of truck brake drums in the past few years show that the rupture is often linked to a defective non-asbestos brake shoe. In addition, a study by the EPA and the American Society for Mechanical Engineers shows that it is dangerous to install non-asbestos brake linings on cars initially designed with linings containing asbestos.

To alleviate the problems of unbalanced non-asbestos brakes, manufacturers have developed anti-locking systems. It is still too soon to evaluate the advantages and risks of these products, but one thing is clear, the price of cars has been increased... without necessarily adding to the safety of consumers.

Replacement of chrysotile in gaskets

It takes 50 to 60 different substances to replace the various grades of chrysotile fiber used in the gasket industry. Development of these substances and their industrial applications involves very costly research for the industry, and hence, increased costs to consumers. Such a composition may result in sudden rupture and shattering of the gasket, particularly in high temperature, high pressure applications. In addition, it requires more frequent inspections than those usually foreseen for chrysotile-based gaskets which were much more resistant.