Kay Fitch

compounds used in fracking, there's very little known about the potential health risks of about one-third of them. This research was presented this week at the 248th National Meeting of the American Chemical Society

William Stringfellow of the Lawrence Berkeley National Laboratory and his team searched through public databases for the most common compounds used in fracking around the U.S. since 2011. The researchers looked at the toxicity of chemicals in the fluid that companies inject into wells to extract natural gas and oil. Eventually their goal is to assess whether any of these chemicals pose a risk to the environment.

Fracking Fluid

The hydraulic fracturing process, or fracking, involves adding a mixture of water and chemicals deep underground to create fissures in shale and release the gas trapped within. The industry has expanded rapidly in the past decade—in the U.S., nine out of 10 new wells use fracking.

Depending on the geology of a well, companies use between five and 30 different chemicals in the approximately seven million gallons of fracking fluid needed for each well. Water makes up most of the fracking fluid, around 85 percent by mass. Other additives include sand, which keeps the fractures open, biocides, which kill bacteria and prevent the well from clogging up, and acids, which clean up mineral debris.

Companies have different formulas for their fluid that they can disclose on websites like FracFocus.org. Some states such as Texas and Wyoming mandate that fracking companies publicly disclose chemicals in their fracking fluid. Depending on the state, though, companies can skirt the mandate by claiming their recipe is a trade secret. For example, in a report that discloses the ingredients in a well in the Eagle Ford shale play of South Texas, one biocide is listed as a "third party biocide" with no other details. However, the industry is facing more and more pressure to stop using trade secrets, Stringfellow says.

The Study

How dangerous are all these chemicals? "The industrial side was saying, 'We're just using food additives, basically making ice cream here,'" Stringfellow says. "On the other side, there's talk about the injection of thousands of toxic chemicals. As scientists, we looked at the debate and asked, 'What's the real story?'"

To decide which chemicals to research, Stringfellow's team looked at government databases including FracFocus.org and focused on 81 fracking chemicals commonly used in the U.S. Because companies frack for oil instead of natural gas in the state of California, the team also found a separate list of compounds used in the Golden State. Once they had their list, they used publicly available data to research each chemical's toxicity.

Of the 190 total compounds the team studied, most were non-toxic or of low toxicity. However, one-third of them have hardly any public information about their toxicity or their physical and chemical properties, and eight are downright toxic to mammals. More information may be available in industry groups, Stringfellow says.

What We Know About Fracking Waste

Though the EPA hasn't found evidence that fracking contaminates groundwater, it's still unknown how it affects wildlife in the long term. Because of the geology of fracking wells, it's unlikely that fracking fluids would be able to migrate far away from the fracking site. "In general, these chemicals are much more dangerous when they're being transported above the ground than after they're injected," says Ian Duncan, who researches the environmental consequences of fracking at the University of Texas in Austin and was not involved in the research. Duncan and Stringfellow say the chemicals of biggest concern are the biocides, which are meant to kill bacteria.

Handling Wastewater

When the fracking's finished, there's a lot of contaminated wastewater that companies need to dispose of. Most commonly, companies inject wastewater into wells that have already been tapped. It's been the cheapest and safest method especially throughout West Texas where there were already plenty of wells to use, but it can cause earthquakes. Energy companies can choose to treat the wastewater; however, they may not be able to completely decontaminate it.

Recycling water may reduce spills and be a better solution to deep well injection and wastewater treatment since it doesn't require road transportation or long pipelines, says Duncan. Recycling involves removing chemicals and rock fragments from fracking wastewater and reusing it to frack more wells. Now 70 percent of the fracking water from the Marcellus Shale gas region in Pennsylvania gets recycled.

Future Research

For the next step, Stringfellow says he plans to study the risk and concentration of the chemicals when mixed into fracturing fluid. Most of the chemicals are diluted. For example, the "third party biocide" in the South Texas well has a concentration of 0.025 percent by mass. But it's also important to look at whether the chemical breaks down once it's injected. "If something just dissipates immediately it's not really a risk. We need to understand the whole chemical," Stringfellow says.

Stringfellow and Duncan say these compounds are not just used in fracking. Biocides are used in everything from hand soap to cooling treatment plants, for instance. "The lack of knowledge about some chemicals is not specific to frack fluids. We only have toxicity information for a fraction of the chemical in use by society," says Duncan. "Fracking is an industrial activity, so safety should always be a concern."

"There's a national need to get a complete picture of the chemicals that are used everyday," Stringfellow says. "It should be a priority to try to close that data gap."

Full Disclosure: Fracking wells operate on land owned by the author's parents.

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