AND WE THOUGHT ALL MINERALS WERE NATURALLY OCCURRING: THE NEED FOR A RATIONAL PUBLIC POLICY DEALING WITH SO-CALLED NATURAL OCCURRING ASBESTOS

Naturally occurring asbestos is the latest hot environmental topic in California. When we first saw the term “naturally occurring asbestos,” we shuddered, because asbestos is a mineral and all minerals, by definition, are naturally occurring. Regardless of our views on this term, it is now widely used by the regulatory community. The current issues plaguing the regulatory agencies in the USA, is how to treat asbestos that is not associated with an occupational work environment and how to define when an amphibole particle is asbestos.

Amphiboles are ubiquitous comprising approximately 5% of the Earth's crust. They occur more commonly in igneous and metamorphic rocks, and somewhat correlate to the mountainous areas of the USA. Fortunately, the asbestiform habit (i.e., particles that are lengthwise separable into fibers) is less common than the nonasbestiform habit. The distinction of particles of amphibole from amphibole asbestos is important because OSHA deregulated nonasbestiform amphiboles in 1992 in the occupational environment. OSHA concluded that: “substantial evidence is lacking to conclude that [nonasbestos amphiboles] present the same type or magnitude of health effects as asbestos.”

Asbestos analysis methods were developed to determine worker exposures to commercial asbestos fibers. Aspect ratio and length were used in order to achieve reproducible counts. Today analysts using light microscopes often use these counting criteria as a definition of asbestos. For instance, an analyst would count any amphibole particle with an aspect ratio greater than 3:1 and longer than 5 microns as asbestos. This makes most amphiboles “asbestos,” which, of course, is incorrect. This erroneous methodology has significant public policy implications.

It must be the goal of the mineralogical, geological, industrial, and regulatory communities to collaborate in finding a common-sense policy when dealing with naturally-occurring materials. Unfortunately, in the case of amphiboles occurring in a geological setting, the opposite appears to be occurring, with the end result being confusion among those faced with making decisions on dealing with this issue and fear and frustration in the general public. As we develop regions of the USA where amphiboles occur in the soils and rocks, this will become even more of an issue.