POLARIZED LIGHT MICROSCOPY (PLM) IN ACADEMIA AND THE ASBESTOS INDUSTRY

PLM has served for decades in geoscience departments as a wonderfully efficient tool for undergraduate students to gain a real hands-on experience in the scientific method. It has also been the primary method in the “for profit” sector for the analytical characterization of “asbestos”.

The downsizing of optical mineralogy in many geosciences departments to either a small part of a mineralogy-petrology course or even the complete elimination of training in this methodology has ramifications for BOTH the training of undergraduate geologists, as well as the regulatory world of “asbestos”. Should we maintain the formal teaching of a full course of Optical Microscopy because “we” learned it and aren’t we great?” or just let it go the way of blowpipe analysis? If we maintain optical mineralogy in the standard curriculum, how can we improve it in light of today’s needs and analytical abilities? In the commercial sector, given the scarcity of trained microscopists for entry level positions, many for profit laboratories often “teach” analysts in a “shake and bake” course which can dilute the quality of PLM analytical results. The requirement of turning a profit, as opposed to “doing science”, can lead to questionable data.

Since the early 1980’s, the focus on what is asbestos and how it is determined has changed from six “things” in three categories of building materials, where asbestos was knowingly and deliberately designed into the product formulation, to scores of materials where asbestos occurs in small to trace amounts. The identification of regulated materials has moved from an amount >1% (by weight or area??) to just about any amount that might pose a biohazard, thereby leading to more costly engineering controls and more complex legal system adjudication.

Illustrative examples include vermiculite; elongate mineral particles (EMPs); talcboles; white and green talcs; “asbestos” in some medicines; and building components.

At the end of this day, it seems to me that we have moved beyond an admirable goal of controlling asbestos hazards in the workplace and non-occupational environments to making stricter and stricter analytical standards, and hence ever more stringent environmental engineering regulations, to deal with “mere presence” rather than reasonable dangers. Form appears to have overcome function!