Controlled use of chrysotile
Controlled use of chrysotile asbestos: 100, 10, 1 or 0.1 f/ml?
It is a government's duty to address health, education, public safety and other such important issues, and to formulate and enforce whatever regulatory measures are deemed necessary. But governments also have the responsibility to consider the costs associated with the actions to reach the desired benefits. In particular, the expected benefits must be significant and measurable. In short, governments must carry out a "cost/benefit analysis".
At the outset, in the formulation and enforcement of appropriate regulations regarding the safe use of chrysotile asbestos in the workplace, a basic principle is obvious: the lower the exposure, the lower the risk. This in turn translates into the question: to what level should the permissible exposure limit (PEL) be lowered in order to reach significant and measurable risk reduction for the workers?
The most recently published and comprehensive data, as well as retrospective reviews of exposure/effect relationships for chrysotile show that when workers exposure is down to approximately 20 f/ml (for 40 years), the excess risk for lung cancer is undetectably low. If one whishes to consider a "safety margin", by implementing a 10-times lower PEL, such as 2 or 1 f/ml, it is obvious that whatever excess risk, if it still exists, will be even more undetectably low. The question then is: what significant and measurable benefits could be expected by further lowering the PEL by a factor 10 (0.2 - 0,1 f/ml)? The answer is: none.
But at the same time, a lowering of the standard will entail significant and measurable costs, in addition to being futile. In applying such stringent standards, the costs are real for the industry and governments, but are in no way scientifically based. On the other hand, there is an alternative: resources could be directed toward other types of interventions that would be certainly more productive, significant and measurable in terms of occupational health and safety, such as information and training programs, more frequent hygienic controls, tighter medical surveillance, etc.
The chrysotile asbestos standard of 1 f/ml, combined with the prohibition of the use of the amphibole varieties, is quite adequate, and even includes a "safety margin". Lowering this standard even further is a waste of resources. Incidentally, this standard was the one recommended by a WHO "Group of Experts" in Oxford in 1989.