Methodologies for determining the sources, characteristics, distribution, and abundance of asbestiform and nonasbestiform amphibole and serpentine in ambient air and water.

摘要: Anthropogenic and nonanthropogenic (erosion) processes contribute to the continuing presence of asbestos nonasbestos elongated mineral particles (EMP) amphibole serpentine in air water urban, rural, remote environments. The anthropogenic include disturbance deterioration asbestos-containing materials, mining amphibole- serpentine-bearing rock, soils containing serpentine. Atmospheric dispersal can transport EMP on a global scale. There are many methods establishing abundance water. cleavage fragments, fibers, asbestos, other asbestiform minerals, employed do not critically distinguish among them. results most protocols expressed common unit fibers per square centimeter; however, seven different definitions for term "fiber" comparable. phase-contrast optical method used occupational monitoring cannot identify being measured, none from amphibole. Measured ambient concentrations airborne low, variance may be high, even similar environments, yielding data questionable value risk assessment. Calculations based amphibole-bearing rock estimates conterminous United States suggest that found 6-10% land area; erosional might produce order 400,000 tons or more year, approximately 50 g asbestos/km(2)/yr; magnitude likelihood encountering bearing any type is 0.0001.