The U.S. Department of Labor has issued a health alert for oil and gas employees working with fine sands commonly used during the controversial practice of hydraulic fracturing.

Recent studies by the U.S. National Institute for the Occupational Safety and Health (NIOSH) found that workers downwind of fracking equipment used to mix, move and blend different sands "had the highest silica exposures."


Workers who breathe fine silica dust are at greater risk for developing silicosis, an incurable but preventable disease that causes inflammation of the lungs and reduces oxygen intake.

The department warns that "silica also can cause lung cancer and has been linked to other diseases, such as tuberculosis, chronic obstructive pulmonary disease, and kidney and autoimmune disease."

Different sized particles of sand (ranging from 0.106 millimeters to 0.85 mm) are a key ingredient in fracturing operations for shale gas and oil shale. In 2010, for example, Apache Corporation used 259 million gallons of water along with 50,000 tonnes of sand to fracture deep shale formations in 16 well sites in B.C.'s Horn River shale gas play.   

Hydraulic fracturing is a brute force technology that propels millions of gallons of water and a concoction of different sized particles of sand, viscous gels and other chemicals at extreme pressures down a well bore in order to crack open dense rock formations a mile or two below the earth's surface.

Sand lodged in the fracture allows small amounts of methane to pass to the surface. If the grains of sand aren't the right size or strong enough, the fracturing operation won't be successful.

The health alert follows comprehensive studies showing high worker exposures to lung-congesting sands at fracking operations. Field studies in five states at 11 fracking sites found that workers were routinely exposed to fine sands sometimes at 10 times above "defined occupational exposure limits."  

Industry demands for "frac sand" are immense. The Horn River play consumed 200,000 tonnes of sand in 2011 while the Montney play pumped underground another 800,000 tonnes.

By 2014 the industry could be pumping nearly $1-billion worth of sand ($325 a tonne) imported from Saskatchewan, Alberta, Wisconsin and even Texas into shale rock formations in northeastern B.C.

Hydraulic fracturing operations in the region, some of the largest in the world, have also been associated with scores of earthquakes in the area.

Award-winning journalist Andrew Nikiforuk writes about energy for The Tyee and others.