After testing 100 water wells atop one of the largest natural gas reserves in the U.S., scientists at the University of Texas have found that nearly 30 percent of them contain levels of arsenic above the limit considered safe by the U.S. Environmental Protection Agency, according to a study published in the journal Environmental Science and Technology.
Twenty-nine groundwater sites within 1.8 miles of active natural gas drilling had unusually high levels of heavy metals, including arsenic, the study found. And while it’s not conclusive that the contamination is because of fracking, the team of 11 biochemists say their findings provide further evidence that could link the controversial natural gas drilling technique to groundwater pollution.
“I can’t say we have a smoking gun. We don’t want the public to take away from this that we have pegged fracking as the cause of these issues,” Brian Fontenot, the paper’s lead author, told ProPublica. “But we have shown that these issues do occur in close relation, geographically, to natural gas extraction.”
The EPA classifies arsenic as a carcinogen, and warns that long-term exposure to it can cause cancer, cardiovascular disease, immunological disorders, diabetes and other medical issues.
Hydraulic fracturing, otherwise known as fracking, is a controversial yet popular technique used to stimulate natural gas wells underground. To do this, companies inject a mixture of water, sand, and chemicals miles-deep into subsurface rock. The high-pressure brine effectively cracks or “fractures” the rock, making gas easier to extract.
The technique is especially popular on the Barnett Shale, a rich source of natural gas located in the Fort Worth Basin. The Barnett Shale is one of two huge active shale plays in Texas, along with the Eagle Ford shale, and together they hold more than 90 trillion cubic feet of unproven, technically recoverable gas. The two shale deposits also represent one of the biggest energy booms in America.
That boom started about 10 years ago, and the University of Texas researchers compared their results with previous water tests conducted before that boom. What they found was what researcher Zacariah Hildenbrand called an “alarming” increase in the amount of arsenic and other heavy metals in 30 percent of the groundwater wells within 1.8 miles of gas drilling sites.
“This is indirect evidence that drilling does affect the water,” Hildenbrand said.
The researchers’ theory about how fracking may have caused the arsenic pollution is that the technique caused increased vibration underground, shaking rusty pipes in the nearby water wells. That rust could contain arsenic, the researchers said. “We’re not saying that [fracking companies have] injected arsenic into these wells,” Fontenot said.
Industry leaders have doubted this theory, telling The Denton Record-Chronicle that vibrations from drilling could never reach shallow water wells because of how deep gas wells are drilled. “If they’re talking about drills shaking [rust] free, that’s a little farfetched,” said Alex Mills, president of Texas Alliance of Energy Producers. “I’ve never heard or even came close to hearing that hydraulic fracturing is so vicious, so earth-shattering to shake loose rust from water wells.”
While it seems that little research has been done on whether drilling itself can cause earth-shattering vibrations, emerging research has shown that fracking can cause the earth to shake. Scientists increasingly believe that the fracking-related process of injecting water underground is causing man-made earthquakes — not only in Texas, but across the country. The large amount of water injected into the ground can change the state of stress on existing fault lines to the point of failure, scientists believe.
The natural gas drilling industry maintains that fracking is safe and doesn’t impact human health. But there has been a lack of conclusive scientific research to support or deny that claim. Preliminary, albeit inconclusive research has shown that fracking could cause health problems in expectant mothers or birth defects in unborn babies living near wells, but scientists largely agree that more research needs to be done as oil and gas production booms across the country.
The University of Texas researchers agree. “We think that the strongest argument we can say is that this needs more research,” Fontenot said.