Development of this family of substitute products has run into many problems. The manufacturing cost is 20% to 30% higher, and many of the products have been demonstrated to be less resistant to heat, humidity and temperature contrasts (freeze-thaw) and thus not as durable as chrysotile-reinforced products. For example, Danish building product giant Dansk-Eternit is currently facing claims totalling in the hundreds of millions of dollars as a result of home owners being supplied defective corrugated roofing sheets using first-generation non-asbestos technology. Several Central American countries have also removed cement- and cellulose-based roofing materials from the market. Several complaints have also been filed in the United States and Great Britain against asbestos-free materials with poor technical performance or durability. Moreover, scientists have begun to raise concerns over the health effects of some of the fibres used to replace chrysotile. Many of these fibres, including cellulose are quite biopersistent, and thus require care during manufacture, handling and use.
Corrugated metal roofs
The production of corrugated galvanized iron sheets consumes 2 to 2-1/2 times more energy than chrysotile-cement. The figure rises even more when the energy content of coatings applied for aesthetic reasons and to prolong the durability of the products is factored in. When the longer service life of chrysotile-cement is factored in, coated galvanized iron sheet is estimated to consume about 5 times more energy than chrysotile-cement sheet production.
Studies have shown that, depending on the type of corrosion protection used, the useful life of corrugated iron roofing is significantly shorter (by one-quarter to one-third) than that of chrysotile-cement roofing. Not only is the maintenance of corrugated iron costly over time, it clearly has inferior acoustic and thermal insulation characteristics.
PVC (polyvinyl chloride)
The principal competing products for chrysotile-cement pressure pipe are PVC and ductile iron. PVC in particular has made great inroads in these markets. There is, however, growing attention from the medical and scientific communities on the potential health and safety risks of these materials. For example, vinyl chloride monomer (VCM) used in PVC is a well known human carcinogen that affects the brain and liver. VCM is also known to leach out of the pipe into drinking water. Furthermore, in developing countries, PVC pipe may contain lead as a stabilizing agent. Concerns have also been raised regarding the quantity of dioxins released into the environment during the production of PVC. In addition, several of the bonding agents used in the installation of PVC pipe are potential toxins.
Overall, the predicted durability of PVC is about 50 years. Chrysotile-cement pipe has an expected life of approximately 70 years. And for the same price, four times as much chrysotile-cement pipe can be installed. Moreover, it is known that PVC pipes do not stand up well to the climactic conditions of certain regions: a rise in water temperature or exposure to ultraviolet rays during storage and installation may damage them.
Ductile iron pipes
Ductile iron pipe is also not without risks. In its landmark ruling overturning the U.S. Environmental Protection Agency¹s asbestos ban, the U.S. Court of Appeals concluded that there is evidence that ductile iron is associated with cancer deaths. The EPA¹s own studies found that the population cancer risk for the production of ductile iron pipe may be comparable to the population cancer risk for the production of asbestos-cement pipe.
Like chrysotile-cement pipe, cast iron pipe with a protective coating has a useful life of about 70 years. The useful life of cast iron may be shorter in more aggressive soils or water, often because of the presence of corrosive agents.