Key-note on NOA at XIII IAEG Congress 2018

Engineering Geology for a Sustainable World

Naturally Occurring Asbestos, a Global Concern?  State of Art and Open Issues
Prof. Alessandro Gualtieri, University of Modena, Modena, Italy
ABSTRACT: Naturally Occurring Asbestos (NOA) has raised concern worldwide since the appearance of evidences in the scientific literature of increased risk of malignant mesothelioma (MM) in the population exposed to airborne asbestos released from natural occurrences. A striking example is represented by the California case, where residential proximity to naturally occurring asbestos was significantly associated with increased risk of mesothelioma (Pan et al., 2005). The risk of mesothelioma decreased approximately 6.3% for every 10 km increase in residential distance from the nearest asbestos source (LaDou et al., 2010). Because NOA is widespread on the Earth’s crust, it represents today a global public health issue. The presence of NOA in the environment affects all the human activities aimed at its modification (e.g. mining activity, tunnels/bridges/dams construction, roads/highways pavement …). Specifically, all engineering/geological activities in the natural environment should take into account if NOA is present. If so, dedicated procedures for sampling, evaluation of environmental risk, and monitoring must be applied in order to minimize the risk of exposure for the workers and population. Unfortunately, shared clear operational procedures are missing to date because basic issue have not been solved yet: first of all, there are overlapping and contradictory definitions for asbestos, elongated mineral particles and asbestiform particles, and their discrimination and counting in NOA is often troublesome or impossible. It is important to show the limits of the existing definitions and make it clear that not even a unique definition of asbestos exists to date. There are open issues that the engineering/geological community must be aware of. For example: (i) when a mineral fiber can be actually classified as asbestos?  (ii) how to properly measure a mineral fiber and classify it as asbestos? (iii) how to determine the concentration of asbestos and mineral fibers in general in massive (e.g. soils)?; (iv) do elongated mineral particles represent an hazard? If we are not aware of these basic issues and attempt to solve them, there will always be controversial positions that make legal issues and outcome of lawsuits very subjective. Recent examples of how these issues impact mining activity in areas possibly “contaminated” with asbestos will be described (Gualtieri et al., 2018). Examples of natural occurrence of unclassified mineral fibers which may represent a potential hazard in Europe and United States will also be discussed.
References: Gualtieri et al. (2018) Journal of hazardous materials, 350, 76-87;  LaDou et al. (2010) Environmental Health Perspectives, 118(7), 897-901; Pan et al. (2005) American Journal of Respiratory and Critical Care Medicine, 172(8), 1019–1025.
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Key-note at XIII IAEG Congress 2018 – Engineering Geology for a Sustainable World – Naturally Occurring Asbestos, a Global Concern? State of Art and Open Issues – Alessandro Gualtieri