Hazards of Asbestos Cement
Preliminary research in Brazil on the hazards posed by fibercement tiles concludes that they "are potential sources for asbestos contamination," because of the progressive degradation of the material;1 "chemical weathering caused by acid attack of fibercement is stronger in industrial urban areas such as Sao Paulo, where rain water has a higher acidity than elsewhere." This problem is particularly severe in Brazil where around 70% of the buildings are covered with fibercement which contains approximately 12.5% chrysotile asbestos by weight.
"Degradation of fibercement tiles due to weathering is relatively underestimated. As any concrete body, fibercement tiles are prone to undergo degradation when exposed to chemical, physical and biological weathering. Degradation of the cement matrix enhances porosity and may lead to detachment of the mineral fibers."
The authors call for a ban on the new use of this material and the replacement of old fibercement roofs by safer materials.
May 17, 2003
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1 Asbestos release through degradation of fibercement, by F.R.D. Andrade, R.B. Santini and Y. Kihara, Institute of Geosciences, University of Sao Pauilo and Portland Cement Brazilian Association.
