Sunday, October 5, 2014

THE RISK OF CRYSTALLINE SILICA EXPOSURE: THE FRAC SAND IS MORE TOXIC THAN AGED QUARTZ SAND

THE RISK OF CRYSTALLINE SILICA EXPOSURE:  THE FRAC SAND IS MORE TOXIC THAN AGED QUARTZ SAND
Dust created during fracking operations.  This dust contains mostly toxic crystalline dust.

We wrote two weeks ago about the potential exposure to harmful radioactive chemicals, hydrogen sulfide, harmful petroleum vapors, and crystalline silica sand during oil & gas exploration and production activities.  This blog addresses some of the latest findings of NIOSH investigators on the harmful effects of the silica sand.  Specifically, in a recent (2014) study NIOSH found that there is a special hazard associated with crystalline silica sand that is freshly fractured.  The following conclusions were reached:


  • Silica dust aerosols generated during sand delivery operations are highly respirable; 
  • The highly respirable silica dust is also freshly fractured;  it is much more toxic than aged quartz;

Photo above shows 40/70 mesh sand before sand transfer (left)  The very fine sand pile at the right was collected at the emission point from the sand handler.

  • There is a large fraction of sub-micron and nano-size particles, and this may suggest even higher toxicity to workers;
  • Engineering controls are currently not sufficient to limit and contain the exposures;
  • The toxic silica sand suppliers and the trucking companies need to become involved in discussions of controls;
  • Wisconsin quarries now ship about 75 percent of the toxic silica sand across the United States by rail.  A number of freight trail derailments have been reported todate.  Our concern is that the cleanup crews are not aware that they are handling a toxic product and that they need to wear respiratory protection.

Photo above shows a recent train derailment where frac sand (the toxic crystalline silica) was spilled.

In 2012, the National Institute for Occupational Safety and Health (NIOSH) released field study findings concerning worker overexposure to airborne silica during hydraulic fracturing operations.  Air samples were collected at 11 North American hydraulic fracturing sites with the following results of 116 samples collected:
  • 47% showed silica exposures greater than the calculated OSHA PEL;
  • 79% showed silica exposures greater than the NIOSH REL of 0.05 milligrams per cubic meter (mg/m3); 
  • 9% of all samples showed silica exposures 10 or more times the PEL, with one sample more than 25 times the PEL; 
  • 31% of all samples showed silica exposures 10 or more times the REL, with one sample more than 100 times the REL. 

Frac sand QUARRY in Wisconsin


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