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HOW ARE THE PHYSICAL AND CHEMICAL PROPERTIES OF CHRYSOTILE ASBESTOS ALTERED BY A 10-YEAR RESIDENCE IN WATER AND UP TO 5 DAYS IN SIMULATED STOMACH ACID
Citation:
Seshan, K. HOW ARE THE PHYSICAL AND CHEMICAL PROPERTIES OF CHRYSOTILE ASBESTOS ALTERED BY A 10-YEAR RESIDENCE IN WATER AND UP TO 5 DAYS IN SIMULATED STOMACH ACID. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-83/263.
Description:
While there are many studies concerning the ingestion of chrysotile asbestos, there are a few studies concerning how the chrysotile asbestos itself is altered by the exposure to the acid stomach environment. It is shown that the charge on the surface, the Zeta potential, is changed from positive to negative; that the surface becomes silica-like, i.e., depleted of Mg++ ions; that Mg++ is lost from the fibers of asbestos upon exposure to water and acid; that the loss of Mg++ is more rapid, the smaller the fiber diameter. Notable among the physical properties, the loss of Mg++ causes the refractive index to change. This means that asbestos exposed to acids or water may not be detectable using the now popular dispersion staining techniques which identify asbestos based on refractive index. The physical property changes include the destruction of the 'gross' crystallinity of the fibers. The x-ray diffraction signal from acid treated fibers disappears. This means that x-ray diffraction cannot be used to identify chrysotile which has been exposed to acid.