A new study exploring the scope of use and the safety of hydraulic fracturing chemicals used for enhanced oil and natural gas production has concluded that few of the roughly 90 commonly used compounds are toxic to people.
But there’s still insufficient information from the oil and gas industry to fully evaluate the safety of the chemical additives, according to the study’s lead author, environmental engineer William T. Stringfellow of the University of the Pacific and Lawrence Berkeley National Laboratory.
Ultimately, the industry needs to be more transparent in revealing toxicity data on the formulations used in fracking, Stringfellow told C&EN.
Stringfellow presented the study results this week during a symposium on the environmental impacts of hydraulic fracturing sponsored by the Division of Environmental Chemistry at the American Chemical Society meeting in San Francisco.
The motivation for the review, Stringfellow said, was to resolve debate about which chemicals are really being used. Some environmental advocates claim that thousands of toxic chemicals are being injected into wells. But the fracking industry has claimed it is only using a few food additives that are also used for making ice cream. “As scientists, we looked at the debate and asked, ‘What’s the real story?’ ”
To find out, Stringfellow and his colleagues sifted through data on the voluntary industry self-reporting website FracFocus and data compiled by the environmental monitoring organization SkyTruth. The team cross-checked the data against Environmental Protection Agency reports and other industry data, but Stringfellow acknowledges some of the information is inaccurate and remains incomplete.
The assessment initially turned up 81 chemicals (J. Hazard. Mater. 2014, DOI: 10.1016/j.jhazmat.2014.04.040). Stringfellow’s list, which has now grown to 90 compounds, includes gelling agents to thicken the fluids, corrosion inhibitors to protect pipes, and biocides to keep microbes from fouling wells. These are used in many different fracking-fluid formulations.
Stringfellow and his colleagues are using a different set of criteria to compile a list of fracking chemicals used in the state of California. That list, which is being generated as part of a scientific assessment for the state, includes 192 compounds, he said. It’s longer because it includes compounds found in trace amounts as impurities in the industrial-grade chemicals used in fracking fluids. It also focuses more on oil production than natural gas.
Fracking fluids do contain many nontoxic and food-grade materials, as the industry asserts, Stringfellow said. “But you can’t take a truckload of ice cream and just dump it down the storm drain,” he observed. On the other hand, little is known about the health risks of more than one-third of the compounds, and eight raised red flags for being toxic to mammals. Biocides, for example, are typically the most toxic chemicals in the formulations.
“By using a systematic approach, we were able to select the commonly used compounds and those of most concern from a baffling list of chemicals,” Stringfellow told C&EN. “The most important public message from our research, in my mind, is that there is an urgent need to measure basic physical, chemical, and biological parameters on all industrial chemicals, not just fracking chemicals, so that informed decisions about the fate and effects of chemicals can be made in an open and transparent manner.” Although the hazards of using chemicals can be managed, he added, green alternatives are needed for the worst actors.
Reviewing the new list, Hong Sun of Houston-based oil- and gas-field services company Baker Hughes and Darren Maley of Canadian firm Trican Well Service both noted that it is a good start. But they found discrepancies in classifying some of the compounds by function, and that some chemicals are missing whereas others listed are rarely or no longer used. Maley suggests the Stringfellow study would benefit from a collaborative review with industry partners to refine the list.
“The oil and gas industry relies too much on others to evaluate the environmental impact of the chemical additives it uses and has been doing a poor job in communicating information with the public,” Sun said. He points out that chemical additives typically make up only about 0.5% of the fracking fluid, which is mostly water and sand. “But if all companies would commit to systematically evaluating and disclosing all the chemical additives in all fracturing treatments, the current study will be more accurate and even more meaningful.”