NATURALLY OCCURRING ASBESTOS - A RECURRING PUBLIC POLICY CHALLENGE

The potential public health issues related to exposure to respirable dusts from the vicinity of naturally occurring asbestos (NOA) deposits have gained the regulatory and media spotlight in many areas around the United States, such as Libby, MT and El Dorado Hills, CA, among others. Airborne asbestos may be released from NOA deposits, absent appropriate engineering controls, and may pose a potential health hazard if these rocks are crushed or exposed to natural weathering and erosion or to human activities that create dust. A major issue that needs to be addressed at a policy level is the method of assessing exposures to elongated rock fragments ubiquitous in dust clouds in these same environments and the associated risk. Cleavage fragments present in NOA have been construed by some as having attributes, including the health effects, of asbestos fibers. As in many environmental fields of study, the evidence is often disputed. Regulatory policy is not uniform on the subject of rock fragments, even within single agencies. The core of the issue is whether the risk parameters associated with exposures to commercial asbestos can or should be applied to rock fragments meeting an arbitrary set of particle dimensions used for counting asbestos fibers. Inappropriate inclusion of particles or fragments results in dilution of risk and needless expenditure of resources. Inappropriate exclusion of particles or fragments may result in increased and unnecessary risk.

This ongoing national dilemma has raised public and business concerns. There has been continuing political and scientific debate and widespread miscommunication over perceived versus actual health risks, the validity of various analytical sampling and testing methods, the questionable necessity and escalating costs of remediation procedures, and the combined negative impact on numerous commercial and public interests. The risk assessment methodology and the analytical technology needed to support inferences drawn from existing research are available, but have not been organized and implemented in the manner needed to resolve the NOA controversy. This presentation will review some of the key issues involved with the current NOA debate and propose improved analytical methodologies for dealing with NOA.