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Silica

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the concern

This writeup is derived from L. J. Bhagia's Non-occupational exposure to silica dust, Indian Journal of Occupational & Environmental Medicine 2012 Sep-Dec; 16(3): 95–100, available through the NIH

Silica is a ubiquitous mineral-- most sand is silica-- found in abundance almost everywhere. It has long been known to cause respiratory problems when people are exposed to large quantities, and industrial sources of silica pollution are particularly problematic, and yet not well understood outside of the study of occupational health.

Most industrial silica is in the form of the crystal quartz. Freshly crushed quartz particles are sharper and more dangerous than aged quartz [1,2,3]. The most dangerous particles are those smaller than 5μm in diameter, and while quartz is tough and hard to break into sizes smaller than 10μm, industrial processes can produce an abundance of sub 5μm particles [4,5].

For these reasons, we're interested in monitoring particles of silica, especially around sand mining operations, which have increased to support the fracking industry, a program supported by the 11th Hour Project.

Monitoring Frac Sand

Wisconsin is the source of most frac sand, and new mines are opening rapidly. Political pressure has increased the Wisconsin Department of Natural Resources to step up efforts at monitoring particulate matter. Monitoring stations have increased from zero monitors in 2011 [6] to 13 industrial monitors in 2014, many provided by the industry in question [7]. Currently only this DNR program and Dr. Crispin Pierce’s team at the University of Wisconsin Eau Claire are monitoring silica PM [8]. Dr. Pierce’s team uses both real-time monitoring equipment that costs several thousand dollars and laboratory tests by the Wisconsin State Lab of Hygiene. While laudable, the scale and range of PM sources make it unlikely that these efforts will produce representative PM data for either the complex exposure dynamics around individual mining sites, let alone over the more than 100 frac sand mining sites in Wisconsin.

Citations

      1. Environmental Protection Agency. Ambient levels and noncancer health effects of inhaled crystalline and Amorphous silica: Health issue assessment. Triangle Park: US EPA; 1996. EPA/600/R-95/115: Chapter 1.
  1. Vallyathan V. Generation of oxygen radicals by minerals and its correlation to cytotoxicity. Environ Health Perspect. 1994;102(Suppl 10):111–5. [PMC free article] [PubMed]

  2. Vallyathan V, Shi XL, Dalal NS, Irr W, Castrinova V. Generation of free radicals from freshly fractured silica dust. Potential role in acute silica-induced lung injury. Am Rev Respir Dis. 1988;138:1213–9. [PubMed]

  3. Bhagia LJ, Parikh DJ, Saiyed HN. Ambient silica monitoring in vicinity of agate industry, Khambhat, India. Indian J Occup Hyg Safety. 2007;1:6–10.

  4. Bhagia LJ, Sadhu HG, Parikh DJ, Karnik AB, Saiyed HN. Prevention, Control and Treatment of Silicosis and Silico-Tuberculosis in Agate Industry Report submitted by National Institute of Occupational Health, Ahmedabad to Indian Council of Medical Research and the Ministry of Health and Family welfare, Government of India. 2004

  5. Page 2, “Report to the Natural Resources Board: Silica Study”. 2011: Wisconsin DNR, AM-40.

  6. “Frac sand health fears rise as mining booms in Wisconsin.” October 06, 2013: Wisconsin Center for Investigative Journalism. http://www.wisconsinwatch.org/2013/10/06/frac-sand-health-fears-rise-as-mining-booms-in-wisconsin/

  7. “Silica Research” UW Eau Claire. http://www.uwec.edu/Watershed/enph/silica & http://people.uwec.edu/piercech/InitialPM.pdf