Interactions of Asbestiform Minerals in the Lungs: How a Geochemist and a Mineralogist Got Funding from the National Institutes of Health
MRIC 2007/08
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"Interactions of Asbestiform Minerals in the Lungs: How a Geochemist and a Mineralogist Got Funding from the National Institutes of Health"
September 25th
Scott Wood - Geological Sciences
Abstract: How asbestiform minerals evolve by reaction in the lung remains poorly understood. It is well known that the proportion of amphibole to chrysotile asbestos found in the lungs of miners and millers is generally much higher than in the material to which they were exposed. This phenomenon is normally explained by either more effective clearance mechanisms or lower biodurability (faster dissolution) of chrysotile in the lungs, both explanations being reasonable.
The goals of our study are twofold; 1) determine the rate of dissolution of tremolite asbestos in simulated lung fluid (Gamble's solution) as a function of pH and organic ligand concentration in order to compare with previous measurements of the dissolution rate of chrysotile; and 2) use geochemical modeling techniques to determine whether transformations of chrystotile or tremolite to other minerals are thermodynamically possible in the lungs. Our dissolution rate measurements confirm that the dissolution rate of tremolite is several orders of magnitude lower than that of chrysotile under lung conditions at similar pH. They also show that some carboxylic acids in Gamble's solution can increase the rate of dissolution of tremolite substantially. Our thermodynamic and kinetic modeling suggests that, especially under closed or nearly closed conditions, phases such as amorphous silica, talc, carbonates and hydroxylapatite could form from either tremolite or chrysotile. To our knowledge, this is the first time that transformation of asbestiform minerals to another mineral form has been suggested and could have important implications for treatment and prognosis of asbestos-related diseases.
Scott Wood - Geological Sciences
Abstract: How asbestiform minerals evolve by reaction in the lung remains poorly understood. It is well known that the proportion of amphibole to chrysotile asbestos found in the lungs of miners and millers is generally much higher than in the material to which they were exposed. This phenomenon is normally explained by either more effective clearance mechanisms or lower biodurability (faster dissolution) of chrysotile in the lungs, both explanations being reasonable.
The goals of our study are twofold; 1) determine the rate of dissolution of tremolite asbestos in simulated lung fluid (Gamble's solution) as a function of pH and organic ligand concentration in order to compare with previous measurements of the dissolution rate of chrysotile; and 2) use geochemical modeling techniques to determine whether transformations of chrystotile or tremolite to other minerals are thermodynamically possible in the lungs. Our dissolution rate measurements confirm that the dissolution rate of tremolite is several orders of magnitude lower than that of chrysotile under lung conditions at similar pH. They also show that some carboxylic acids in Gamble's solution can increase the rate of dissolution of tremolite substantially. Our thermodynamic and kinetic modeling suggests that, especially under closed or nearly closed conditions, phases such as amorphous silica, talc, carbonates and hydroxylapatite could form from either tremolite or chrysotile. To our knowledge, this is the first time that transformation of asbestiform minerals to another mineral form has been suggested and could have important implications for treatment and prognosis of asbestos-related diseases.
Original url: http://www.uidaho.edu/class/mric/archives/pre-2010/fall2007/wood