Silica Video 1: Introduction to Crystalline Silica Health Risks

“Hello, I’m Dr. Crispin Pierce, Associate Professor and Director of the Environmental
Public Health Program at the University of Wisconsin-Eau Claire. I’d like to introduce
three students conducting research in my laboratory: James Fay, Greg Nelson, and Andy
“Oil, gas, and sand mining companies in Wisconsin and around the country are actively
mining and processing sand. This sand is mixed with water and chemicals and injected
into wells thousands of meters deep to fracture geologic formations such as shale, in
order to remove gas and oil as energy sources. This process is called ‘fracking’ or
hydraulic fracturing.
“Because there are many mines and processing plants proposed or being constructed in
Wisconsin, and because there is limited understanding of health risks from these
processes, we have created this informational video clip.
“The extraction and use of gas and oil through hydraulic fracturing may have benefits,
potentially reducing US dependence on foreign sources of petroleum. Also, one of the
gases collected in this process — methane — produces fewer greenhouse gas emissions
per unit of energy when used as an energy source compared to coal or oil. However, if
this methane is released into the atmosphere from drilling or leaking wells, it negatively
contributes to climate change, according to a study at Cornell University.
“Another major concern with hydraulic fracturing is the potential for groundwater
contamination. This occurs when the chemicals injected into the wells under high
pressure to fracture rocks for gas and oil collection leak out. Wells and surface waters
near hydraulic fracturing operations have been contaminated with chemicals including
methane, benzene and radioactive elements.
“Our research is focused on small particles of crystalline silica, also called quartz, which
gets into the air when sandstone is mined and when sand is processed for hydraulic
fracturing. Breathing this mineral in work settings is associated with silicosis, a disease
that harms the lungs, as well as lung cancer. We are interested in identifying a
crystalline silica exposure standard to protect the public and in monitoring sand mines
and processing plants to ensure public exposure is below this standard.”
“Crystalline silica is much more dangerous than just dust; like asbestos, its shape and
chemical properties cause significant damage to lung tissues. Also, “freshly-fractured”
silica generated from industrial processes is more damaging to the lungs than silica in
dust from crop fields.
“Based on exposures in the workplace, we know that exposure to crystalline silica
causes silicosis and lung cancer.
“Like all particles that we breathe in, size makes a big difference. Larger particles are
caught in the nose, throat, and upper lung. The more dangerous small particles,
sometimes called “fines” and “ultrafines,” get into the deep lung where they can’t be
easily removed. Crystalline silica also reacts with these tissues, causing inflammation,
scarring and lung cancer.
“To protect people, we use equipment that filters out the large particles and measures
the small particles, called “respirable” particles. There are three ways to measure these
particles: a particle counter, a mass counter, and a filter. In each case, air containing
silica is pulled through a device to count or collect the silica particles. Let’s see how this
“Here we have a particle counter, which I’ll start up.” (POINT TO DYLOS AND TURN ON).
With this instrument, we are measuring the number of particles in a cubic foot of air.
“And here is a mass counter, which I’ll turn on.” (POINT TO DUSTTRAK AND TURN ON)
With this instrument, we are measuring the mass of particles in a cubic meter of air.
“When we consider any exposure to silica from mining or processing activities, we must
include measurements of background exposure. This can be done by taking
measurements before mining or plant activity begins, or measurements in the same
general area that wouldn’t be affected, for example upwind of any activities.
“We can see that the background level of respirable particles on the mass counter is
1microgram per cubic meter. The background level of small particles, in this case called
“PM 2.5” on the particle counter is about 30,000 particles per cubic foot – we get this
value by subtracting the smaller number readout from the larger number and
multiplying by a factor of one hundred.
“Now, let’s generate some silica particles. We’ve put Wisconsin sandstone in the beaker
and are slowly breaking it up using the magnetic stirrer to simulate mining and
processing activities. Looking at the mass counter, we see that the respirable level is
now 70 micrograms per cubic meter, an increase of 69 micrograms per cubic meter.
Notice that although the level of silica particles has increased by 69 micrograms per
cubic meter, the air does not look dusty. This is why measurements of air
concentrations of crystalline silica are needed.
“Five states are now regulating crystalline silica exposure to the public. Two states have
done a thorough job of analyzing how many workers developed silicosis or lung cancer
from silica exposure. The State of California has established a risk level of 3 micrograms
per cubic meter for developing silicosis, and the State of Texas has established a risk
level of 0.27 micrograms per cubic meter for developing lung cancer. Note that the level
of silica we generated was 23 times greater than the California standard and 259 times
greater than the Texas standard.
“Unfortunately, the State of Wisconsin has not adopted a standard for crystalline silica
exposure to protect the public.
“Measurement of background and incremental respirable silica concentrations due to
sand mining and processing is important to protect public health. We urge the
Wisconsin Department of Natural Resources to adopt a standard to protect the public
and to mandate that all industrial processes that generate silica be monitored and
required to meet this standard.”
“For references to the information we have provided or to contact us, please see the
 De Berardis et al. (2007) Airborne silica levels in an urban area. Sci Total Environ.
2007 Sep 1;382(2-3):251-8. Epub 2007 Jun 5.
 EPA (1996) Ambient Levels andNoncancer Health Effects of Inhaled Crystalline
and Amorphous Silica: Health Issue Assessment. EPA/600/R-95/115 (1996).
 Myers (2010) Status Report to the Natural Resources Board: Silica Study:
 NIOSH (2008) Silicosis: Number of deaths, crude and age-adjusted mortality
rates, U.S. residents age 15 and over, 1968-1992:
 OEHHA (2005): State of California Office of Environmental Health Hazard
 WIKIPEDIA: Hydraulic Fracturing,
For further information, contact:
Crispin Pierce, PhD
University of Wisconsin-Eau Claire
(715) 836-5589
[email protected]