Potential Public Health Risks of Silica
Sand Mining and Processing
Wayne L Feyereisn MD FACP
Disclaimer
• No financial disclosures
• Research performed on personal time
• References are based on peer reviewed
journal articles except where noted
• “What is needed “ section is authors
conclusions based on the information
presented.
The Main Message
What is Silica Sand?
Why is “our” sand important?
• It’s Round – therefore it works better to pipe it
down wells and Prop open fractured layers of
shale
• Its Hard- 8000 PSI of compression strength
• Its Plentiful
Why our sand is plentiful
Why is it risky?
• Our lungs have a great clearing mechanism in
the bronchi- Anything larger than 10 microns
is effectively cleared. Deposited in the mucus
layer, goes to our gut and gets cleared.
• Anything smaller than 10 microns, especially
those particles smaller than 4 microns easily
go all the way to the alveoli (air sacs )
Size Matters
Why is it risky?
What does it look like?
What else?
• Silicosis is a Class 1 Carcinogen- that is it is
known to cause cancer.
• Implicated in cases of COPD Chronic
Obstructive Pulmonary Disease
• Implicated in autoimmune diseases including
Scleroderma
– Scleroderma
Rheumatoid Arthritis
–
Rheumatoid Arthritis Wegener’s Granulomatosis
Lupus
– Lupus
IgA Nephropathy
– Wegener’s Granulomatosis
What is special about Silica?
What is special about Silica?
What is special about Silica?
• We have special cells (macrophages) to clear
anything that makes it to the level of the
alveoli (the air sacs).
• The macrophages have a limit about how
much they can clear
• If the limit is exceeded, the cell dies, scar
tissue happens. Scar tissue limits lung
expansion and oxygen exchange= SILICOSIS
What is “the Limit”?
•
•
•
•
•
This is the million dollar question.
Studies based on gold and hardrock mining.
Kreiss &Zehn 41.6 years
Exposure of .05 mg/m3 30 cases/100 workers
Exposure of 0.10 mg/m3 90 cases/100
workers.
• Other studies Hnizdo & Suis-Cremer 1993,
Muir et al 1991, somewhat similar findings
What is the limit?
• Only 5 states have standards
• The State of California has done several
research studies around sand and gravel
mines and its OEHHS has set a standard of 3
ug/m3 as a maximal exposure risk (Myers
2010)
• It requires monitoring of air around all sand
mines and processing plants
What is the big deal about
standards?
Death rates by state 1996 to 2005 – MN 40 deaths in that period of time.
Niosh has a different standard of 50ug/m3
• How much respirable crystalline silica is the NIOSH REL
(Reasonable exposure limits)?
• 500 micrograms (μg’s)
• Photo: Geoff Plumlee, USGS
• NIOSH REL = 0.05 mg/m3 TWA
• 0.05 mg/m3 = 50 micrograms (μg)
• mg/m3
• 1 m3 of air = 1,000 liters
• Normal breathing rate (moderate work, 1 work day) = 10 m3
(10,000 liters of air)
• 50 micrograms x 10 m3 = 500 μg’s
Really-How much is this?
500 ug
Why is it difficult to figure out what
the silica will do if you have daily
exposure?
Data from new cases 1993 to 2006 in Michigan and New Jersey –CDC eWorld
Its just the construction workers
right?
Primary Cases of silicosis 2000-2002 in California by Occupation.
Facts and Fallacies
• Statements made by proponents of sand
mining
• Facts about the issues they comment on
Proponent statement
“Industrial Silica Sand is Safe”
• Depending on use for natural gas or for oil.
Sand used for fracking is generally in the 20-70
sieve size range.
• Pure round sand, with no contaminants, after
processing- “Should be safe”
– BUT
We just take off the top layers which are
the Industrial Sand that carries no health
risk-we leave the rest alone
Silica Sand is a mix
• 25-50% of sand they mine they refer to as
“fines”
– Simply put this is sand below their usable size limit
of .2mm or 70 sieve
– All sands are mixtures in their natural state though
there may be more fine sand at the bottom of a
vein of sand than near the top.
What about the washed sand
when its ready for transport its
safe correct?
• Worker Exposure to Crystalline Silica During
Hydraulic Fracturing – Eric Esswein MSPH et al.
Silica exceeded exposure limits
• 92 of 116 (79%) air samples collected at
hydraulic fracturing sites exceeded the NIOSH
REL for PM2.5
• 36 of the 116 (31%) samples exceeded the
NIOSH REL by a factor of 10 or more.
• The significance of these findings is that even
if workers are properly using half-mask airpurifying respirators, they would not be
sufficiently protected .
Silica sand is no different than Sandbox
Sand
Fallacy
How Industrial Silica Sand is different
• MAGNITUDE:1 cubic yard vs 1000’s of cubic
yards at a sand mine
• DURATION:Sandbox’s operate for an hour
Sand Mines operate for 16 hours day
• AGGITATION AND MANIPULATION: Front end
loaders, crushers, blasting, trucking vs hand
shovel and plastic bucket.
Silica Particulate Monitoring
This is a Sharp Thermoscientific Model 5030 It can detect PM2.5 down to
0.5 ug/ m3
EOG Chippewa Falls
• Monitoring by Crispin Pierce PhD and students
• Ongoing studies with perimeter monitoring.
• Studying PM 10 PM2.5 Preliminary finding of
some readings above New York standards and
at or near current California standards.
Ambient Silica is At or Near Standards from
Other States
0.005
0.0045
SiO2 Concentration (mg/m3)
0.004
0.0035
CA RfC 0.003
mg/m3
0.003
0.0025
0.002
0.0015
0.001
0.0005
TX RfC 0.00027 mg/m3
0
WOHL
FALK
EOG
Preliminary PM 4 silica data from an industry-sponsored study (John Richards, PhD)
has measured the presence of silica at EOG (and the Towns of Howard and Cooks
Valley mines) at around 0.0005—0.001 mg/m3).
Silica Standards
• Standards in 5 states for Silica in Ambient Air
• California 3 mcg/m3- based on non-cancer (silicosis
risk)
• Texas 0.27 mcg/m3- based on cancer risk exceeding
1/100,000
• New York 0.6 mcg/m3
• Minnesota NO STANDARD
• Wisconsin NO STANDARD
• Are you seeing a problem here?
PM2.5 Study EOG Plant Operating
http://people.uwec.edu/piercech/InitialPM.pd
f
By Crispin Pierce et al U of W Eau Claire
PM 2.5 Under Varying conditions
Crispin Pierce et al http://people.uwec.edu/piercech/InitialPM.pdf
We use polyacrylamide as a
flocculent and it is perfectly safe
• Fact or Fallacy?
• Polyacrylamide IS safe.
• It breaks down to Acrylamide- not safe at all
– Heat breaks it down
– Shear forces break it down
• Acrylamide is a neurotoxin, that is, it damages
peripheral nerves and the brain. It also is
considered a class 2b carcinogen
Acrylamide
• Its concentration can increase in a holding
pond due to UV irradiation. It also after a
period of time will start to decrease in
concentration.
• It can be spread in a thin layer over dirt and be
rendered inert.
• If it washes quickly through sand into the
aquifer it is toxic
• .5 parts per billion makes water undrinkable
– World Health Organization standard 2011
Spills don’t happen do they?
Preferred Sands Blair Wisconsin
Sand Spills don’t happen do they?
When the pond spills so does the
acrylamide
Soderbeck mine near Grantsburg WI
b
Polluted water flows to beaver
dam, then to St. Croix River
Sediment-filled water
overflows holding
pond and flows
downhill to creek
Additional Medical Risks
• Diesel Particulates
– Known carcinogen in concentration
– It shortens the lives of 22,000 people/year
– http://www.4cleanair.org/comments/cancerriskre
port.pdf
– Known risk for cardiovascular events -50%
increased risk of heart attacks with acute
exposure. Greater risk walking or riding a bike
than in a car.
Additional Medical Risks
• Diesel Particulates
• http://www.catf.us/diesel/dieselhealth/count
y.php?c=27169&site=0
• Winona
• The lifetime cancer risk from diesel soot in your community
exceeds the risk of all other air toxins tracked by EPA
combined. 80th Percentile of all US Counties
• The average lifetime diesel soot cancer risk for a resident of
Winona County is 1 in 22,418
• This risk is 45 times greater than EPA's acceptable cancer level
of 1 in a million.
• How the Risk from Diesel Soot in Winona
County Compares to Other Minnesota
Counties:Rank Within State: 13 of 87 counties
Winona counties cancer risk is 45 times greater than EPA's acceptable cancer level of 1 in a million
Diesel use by mines
• EAW’s for Dobelstein and Yoder (example)
each would use 500,000 gallons of diesel /year
• All of Minnesota’s diesel use per day of #2
diesel at the retail level is 250,000 gallons
Additional Medical Risks
• Traffic Safety
– 1 in 5 collisions with trucks this size= death
• Water Quality
– During Mining
• Diesel and hydraulic leakage
• Chemicals in sand hauled back to mine
Additional Medical Risks
• Water Quality Risks after mining complete
– Alteration in pH due to sulfites exposed during
mining
– Contaminants entering ground water through
Karst Topography- continued enhanced risk of
chemicals and bacteria after finished with reduced
filtration bed.
What is needed
• Silica air standards , review of current
standards and determine which one, but
choose one
• Require that all sand mining and processing
operations install air monitors every 1000 feet
on the perimeter and meet three standards:
– The 3 or .27 or 0.6 ug/m3 standard for silica
– The EPA PM 10 NAAQS standard
– The EPA PM 2.5 standards
What is needed
• Acrylamide monitoring of pond water
• Acrylamide monitoring of drying facilities at
sand processing site for air
• Acrylamide monitoring of sand returned to
the sand mine
• Minimize diesel use (no roadway transport of
sand)
What is needed.
• Sand mines and processing are coming AHEAD
of the regulation-That is a problem
• The safest way to mine and process sand is:
– Start by having the plant and processing facility in
the least densely populated area’s
– -The further from the epicenter of this activity the
lower the risk
• Rail spurs directly into the facility-No trucks to
transport
The Main Message
Questions?
Wayne L Feyereisn M.D. FACP
References
Silica Sand Mining Information. Winona County. http://www.co.winona.mn.us/page/3038
Occupational silica exposure and risk of various diseases: an analysis using death certificates
from 27 states of the United States. Calvert, G M 1; Rice, F L 2; Boiano, J M 1; Sheehy, J W 3;
Sanderson, W T 1 Occupational & Environmental Medicine. 60(2):122-129, February 2003.
Silica, crystalline (as respirable dust). Nov 2010. Centers for Disease Control and Prevention.
http://www.cdc.gov/niosh/npg/npgd0684.html
Exposure to silica and silicosis among tin miners in China: exposure–response analyses and risk
assessment. Occup. Environ. Med. 58, 31–37. 2001. Chen, W., Zhuang, Z., AttWeld, M.D., Chen,
B.T., Gao, P., Harrison, J.C., Fu, C., Chen, J.Q., Wallace, W.E.,
References
Silicosis: State-Based Surveillance. Dec 2012. Nation Institute for Occupational Safety and
Health. Centers for Disease Control and Prevention.
http://www2a.cdc.gov/drds/worldreportdata/FigureTableDetails.asp?FigureTableID=2599&Gr
oupRefNumber=F03-05
Worker Exposure to Crystalline Silica During Hydraulic Fracturing. May 2012. Esswein E, MSPH,
Kiefer M, MS, Snawder J. PhD, Breitenstein M, BS. http://blogs.cdc.gov/niosh-scienceblog/2012/05/silica-fracking/
Regulatory Toxicology and Pharmacology 43 (2005) 292–300. doi:10.1016/j.yrtph.2005.08.003.
Development of a chronic inhalation reference level for respirable crystalline silica. Collins J,
Salmon A, Brown J, Marty M, Alexee G.
Silica Crystalline Forms. Oct 2009. Development Support Document. TCEQ.
http://www.tceq.com/assets/public/implementation/tox/dsd/final/october09/silica_crystallin
e_forms.pdf
Fracturing Sand Mining and Processing[Absract]. Epidemiology. 23(5s) (ISEE 2012 Conference
Abstracts). September 2012. University of Wisconsin-Eau Claire. Pierce C, Fay K, Nelson G.
References
Crispin Pierce. Personal Communication and Posted Results. UW Eau Claire.
http://www.uwec.edu/CONHS/programs/enph/silica/silicaresearch1.htm
Environmental Degradation of Polyacrylamides II. Effects of Environmental (Outdoor) Exposure
Ecotoxicology and Environmental Safety v.37, n.1, 1jun97Also see Monsanto, Roundup, and
Glyphosate. Eldon A. Smith,*,1 Susan L. Prues,* and Frederick W. Oehme
*GEO-CENTERS, Inc., at Naval Medical Research Institute Detachment (Toxicology), Building 433,
Area B, 2612 Fifth Street, Wright-Patterson AFB, Ohio
45433-7903; and †Comparative Toxicology Laboratories, College of Veterinary Medicine
"Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor)
exposure." Ecotoxicology and Environmental Safety 37 (1): 76–91. (June 1997). DOI:
10.1006/eesa.1997.1527. Smith EA, Prues SL, Oehme FW
http://www.mindfully.org/Plastic/Polymers/Polyacrylamides-Degradation1jun97.htm.
Degradation of Polyacrylamide by Shear Forces. Taeho Rho, Jonseong Park et al “degradation of
polyacrylamide in dilute solution” Polymer Degradation and Stability 51 (1996) 287-293
rnnfm.korea.ac.kr/publication/2008/1995_51_287.pdf
References
Basic Information about Acrylamide in Drinking Water. May 2012. United States Environmental
Protection Agency. http://water.epa.gov/drink/contaminants/basicinformation/acrylamide.cfm
Acrylamide in Drinking-water. WHO/SDE/WSH/03.04/71/Rev/1
http://www.who.int/water_sanitation_health/dwq/chemicals/acrylamide.pdf.
National Toxicology Program, Department of Health and Human Services. Diesel exhaust
particulates report on carcinogens. 12th Edition. 2011.
http://ntp.niehs.nih.gov/ntp/roc/twelfth/profiles/DieselExhaustParticulates.pdf.
International Agency for Research on Cancer. Monographs on the Evaluation of Carcinogenic
Risks to Humans. Diesel and gasoline engine exhausts and some nitroarenes. Lyon (France): vol.
105; 2012. p. 5–12. Available at: http://www.iarc.fr/en/mediacentre/
aircrews/2012/mono105-info.php.
References
McDonald JD, Campen MJ, Harrod KS, et al. Engine-operating load influences diesel exhaust
Composition and cardiopulmonary and immune responses. Environ Health Perspective 2011;
119(8):1136–41. Pronk A, Coble J, Stewart PA. Occupational exposure to diesel exhaust: a
literature review. J Expo Sci Environ Epidemiology 2009; 19:443–57.
Acute exposure to diesel exhausts induces immediate platelet activation. Wauters A., Dreyfuss
C., Hendrick P., Wijns W., Pradier O., Berkenboom G., Van De Borne P., Argacha J.-F. European
Heart Journal. ESC Congress 2012 Munchen Germany... Conference Publication: (var.pagings). 33
(pp 307-308), August 2012. [Journal: Conference Abstract] Oxford University Press
Diesel Soot Health Impacts. Clean air Task Force.
http://www.catf.us/diesel/dieselhealth/faq.php?site=0
A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes. CATF
Special Report 2007-1. Version 1.1 April 2010. L. Bruce Hill, Ph.D. James Gooch.
http://www.catf.us/resources/publications/files/Multi_City_Commuter_Exposure_Report.pdf