THE CHALLENGES OF DEFINING AND CHARACTERIZING ASBESTOS

Existing asbestos analytical protocols were developed on the assumption that the mineral fibers being evaluated were commercially produced asbestos fibers either contained in bulk products or derived from such products. However, when evaluating raw material where amphibole or serpentine mineral may be a common gangue mineral, the presumption that these particles are asbestos fibers is not valid. There is a perception that asbestos analytical procedures, written 10 or more years ago, are the final authoritative statement on asbestos analyses. There have been developments in all aspects of asbestos analyses including optical and electron microscopy. These include the enumeration of the number of asbestos characteristics observed on particles as a basis for classifying the particle as an asbestos fiber, examining the cross section of the fiber, 3-D imaging using electron microscopy, increased use of the field emission scanning electron microscope, and increased emphasis on using particle width (in addition to aspect ratio) in determining if a particle is asbestos or non-asbestos. This presentation will discuss these advances as they apply to the evaluation of raw materials.