(NaturalNews) For years, scientists and residents of areas where fracking is performed have raised concerns that the controversial mining practice could be causing cancer. Now a direct link has been demonstrated for the first time, in a collaborative study by numerous respected U.S. and Chinese institutions, and published in the journal Toxicology and Applied Pharmacology.

Fracking, formally known as "hydraulic fracturing," is a technique for extracting petrochemicals from tough shale deposits that are inaccessible to conventional drilling techniques. A combination of new technologies and diminishing supplies of easier-to-mine oil and gas has led to a boom in the formerly unprofitable technique, particularly in North America.
 

Billions of gallons of water contaminated per day

Fracking consists of injecting water, sand and a secret, proprietary cocktail of chemicals at very high pressure to depths of between 6,000 and 10,000 feet. The pressure causes a series of tiny fractures in the bedrock, radiating out as far as 1,000 feet from the well. The fractures then decrease the pressure, causing the injected water to flow back to the surface. Once the ground has been fractured in this fashion, oil and gas drilling can proceed.

But what about all that water that has flowed back up from the depths of the earth? It turns out that in addition to the toxic chemicals injected as part of the fracking process, the water also brings up heavy metals, volatile organics and radioactive isotopes that naturally occur thousands of feet underground.

The amount of toxic water being produced by this industry is astronomical. Fracking a single well takes an average of 5.5 million gallons of water, 30 to 70 percent of which comes back to the surface. In Pennsylvania alone, there are more than 7,700 active fracking wells, producing billions of gallons worth of wastewater.

So where does the wastewater go? Although it could technically be taken to a water treatment plant, it is instead typically injected back into the ground, either onsite or at a designated wastewater injection site. According to the Environmental Protection Agency (EPA), there are 144,000 such injection sites in the United States, collectively receiving about 2 billion gallons of fracking wastewater each day.
 

Wastewater turns cells cancerous

In the new study, researchers injected wastewater collected from fracking wells into mice genetically predisposed to developing tumors. Mice injected with wastewater developed tumors starting as early as three months after injection, compared with none of the mice from the control group developing tumors after six months. The wastewater also caused malignant changes in human bronchial epithelial cells in the laboratory. These findings establish fracking wastewater as a carcinogen for animals and for human cells.