NATURALLY-OCCURRING ASBESTOS AND PUBLIC HEALTH: THE IMPORTANCE OF INTERDISCIPLINARY RESEARCH (Invited Presentation)

Integrated earth science and medical research is critical to the identification and assessment of non-occupational exposure to hazardous geologic materials. To illustrate the importance and arc of such interdisciplinary studies, we review two case studies of naturally-occurring asbestos (NOA), one a literature review of Biancavilla, Italy (Grosse et al 2014 Lancet and references) and one based on our work in southern Nevada with our medical collaborators (Buck et al 2013 SSSA; Baumann et al 2015 J. Thorac Oncol).

Mesothelioma is a clear indicator of asbestos exposure; meso patients are dominantly male (M:F 2-9) and the disease appears late in life (~65+ years) with occupational exposure due to the disease’s long latency after exposures starting in adulthood. At Biancavilla, epidemiology studies revealed meso patients with M:F ratio of 1:1, including numerous young adults (<50 years) suggesting non-occupational exposure as early as birth. This finding led to the search for NOA and discovery of a previously unknown fibrous amphibole, fluoro-edenite. Fluoro-edenite was found in altered volcanic rocks that was quarried and used as road and building materials. Additional work collected patient histories to rule out occupational exposure, identified fluoro-edenite in diseased tissue, demonstrated fluoro-edenite carcinogenesis in vivo, recognized asbestos-related diseases beyond mesothelioma, and documented pathways to human exposure.

A county-level epidemiological study of mesothelioma data from southern Nevada revealed unusually young meso cases and M:F ratio of 1:1 for patients under 55 years consistent with non-occupational NOA exposure. Geologic studies led to the discovery of previously unreported actinolite asbestos in rocks and soils in and around Boulder City, including in the path of a planned highway project. Additional environmental testing for the project confirmed actinolite asbestos; the project proceeded with additional funding for asbestos mitigation during construction. The arid and dusty conditions of southern Nevada, and the distribution of NOA in urban areas and nearby outdoor recreation areas presents both occupational and non-occupation pathways for human exposure to NOA. Additional medical studies are needed to assess the impacts, if any, to human health in southern Nevada.