EVALUATING THE DISTRIBUTION OF MINERALS LISTED AS GROUP ONE HUMAN CARCINOGENS IN SOILS ACROSS THE CONTERMINOUS UNITED STATES

The International Agency for Cancer (IARC) has deemed 113 “agents and groups of agents” as group 1 human carcinogens (i.e., known to cause cancer in humans). Of those there are three entries for minerals: 1) asbestos (i.e., chrysotile, crocidolite, amosite, asbestiform anthophyllite, asbestiform tremolite, and asbestiform actinolite), 2) erionite (a rare zeolite), and 3) crystalline silica (quartz or cristobalite) dust. Our past work (Thompson et al., 2011) used the USDA database to evaluate the distribution of amphiboles in the USA, while our older publications discussed the concentration of quartz in PM10 in Idaho (Norton and Gunter, 1999) and the fact quartz was listed as a group 1 human carcinogen (Gunter, 1999).

Our current project uses recently-published USGS data (Smith et al., 2013) where multiple samples were collected at 4,857 locations. We focus on the distribution of regulated and potentially regulated minerals such as amphiboles, serpentine, and quartz in soils. Concentrations of these minerals in the A and C soil horizons were determined by the Rietveld refinement method using powder X-ray diffraction data. As would be expected quartz was ubiquitous occurring in all 48 states, 35 states contained amphibole, and 5 states contained serpentine-group minerals. In general the amphiboles occurred in association with soils associated with the locations of igneous and metamorphic rocks, and sediments derived at some distance from them. Of course, just because an amphibole or serpentine group mineral occurs in the soil, it is not de facto asbestos, but as explained in Thompson et al. (2011), the definitions used for asbestos become important.

Gunter, M.E. (1999) Quartz - the most abundant mineral species in the earth's crust and a human carcinogen? Journal of Geoscience Education, 47, 341-349.

Norton, M.R. and Gunter, M.E. (1999) Relationships between respiratory diseases and quartz-rich dust in Idaho. American Mineralogist, 84, 1009-1019.

Smith et al. (2013) Geochemical and Mineralogical Data for Soils of the Conterminous United States: http://pubs.usgs.gov/ds/801/

Thompson et al. (2011) Amphibole asbestos soil contamination in the USA: A matter of definition. American Mineralogist, 690-693: http://ammin.geoscienceworld.org/content/96/4/690.full.pdf