The debate on banning asbestos

I proposed that the toxicity of chrysotile asbestos is much lower than that of other types of asbestos and that it may be close to that of substitutes.¹ Additionally, before a decision is made on whether or not to ban asbestos the technical efficiency of substitutes compared with chrysotile must be weighed for products that have intrinsic safety characteristics. Overall, like Richard Wilson and colleagues, I favour a comparative risk assessment approach. Although substitutes may prove to be better products with respect to human health, this has not yet been shown. Substitutes are associated with some risks, however small, and must therefore be considered critically. In fact, even a substitute 10 times less toxic than chrysotile should be regulated and controlled as tightly as chrysotile if we want to reduce risks. If we tolerate higher exposures to a substitute than to chrysotile, we could well offset the benefits of the lower toxicity of that substitute. Any ban or substitution policy should stipulate standards for substitutes likely to reduce risks.

The letters to CMAJ on banning chrysotile exhibit various viewpoints. I cannot address all of the important issues here, but I caution against putting moral judgements before fact-finding. No doubt all of the letter writers would agree that chrysotile is a carcinogen, but some of them seem to dismiss exposure–response relationships and the lower, possibly “acceptable” risks associated with lower exposures today. Any chrysotile-related risk may seem immoral to them, yet they are not critical about risks associated with chrysotile substitutes. How is it more moral to apply the precautionary principle only to chrysotile rather than to both chrysotile and its substitutes? Oversimplification and avoidance of evidence make it easier to make decisions but they result in hazardous policies.

David Muir and Laurie Kazan-Allen raise the issue of exporting hazardous materials and products. It seems desirable to caution the countries to which we export such materials and products against incorrect uses and careless exposures. Such cautions would apply to both asbestos and substitute products. However, it is not obvious how to do this without being paternalistic. This problem may be addressed by better labelling, cooperative education, training programs and improvements in the “traceability” of products. International laws might be enacted to hold producers and exporters responsible for the detrimental health effects of their products. I am not sure. Generally, more care should be taken to protect the most vulnerable sectors of any society against overexposure to toxic substances such as chrysotile and its substitutes.

Signature

Michel Camus
Science Affairs and Statistics Division Health Canada Montreal, Que.