Comparative hazards of chrysotile asbestos and its substitutes: a Europeanperspective

Although the use of amphibole asbestos (crocidolite and amosite) has been b anned in most European countries because of its known effects on the lung a nd pleura, chrysotile asbestos remains in use in a number of widely used pr oducts, notably asbestos cement and friction linings in vehicle brakes and clutches. A ban on chrysotile throughout the European Union for these remai ning applications is currently under consideration, but this requires confi dence in the safety of substitute materials. The main substitutes for the r esidual uses of chrysotile are p-aramid, polyvinyl alcohol (PVA), and cellu lose fibers, and it is these materials that are evaluated here. Because it critically affects both exposure concentrations and deposition in the lung, diameter is a key determinant of the intrinsic hazard of a fiber; the prop ensity of a material to release fibers into the air is also important. It i s generally accepted that to be pathogenic to the lung or pleura, fibers mu st be long, thin, and durable; fiber chemistry may also be significant. The se basic principles are used in a pragmatic way to form a judgement on the relative safety of the substitute materials, racing into account what is kn own about their hazardous properties and also the potential for uncontrolle d exposures during a lifetime of use (including disposal). We conclude that chrysotile asbestos is intrinsically more hazardous than p-aramid, PVA, or cellulose fibers and that its continued use in asbestos-cement products an d friction materials is not justifiable in the face of available technicall y adequate substitutes.