Hydraulic fracturing, or fracking, is touted as the key to unlocking America’s natural gas reserves. But questions linger about the potential environmental and health impacts of this rapidly booming practice. Now, a new study finds that water samples taken from near fracking sites with recent spills show traces of chemicals that could disrupt the normal functioning of hormones in the body.

Endocrine-disrupting chemicals (EDCs) are a class of substances that occur both naturally in the environment and in man-made sources. They can alter how a person’s body responds to hormones like testosterone or estrogen. This impaired functioning is implicated in a wide range of disorders, from developmental problems and learning disabilities to cancer and reproductive abnormalities.

“One of the real concerns about endocrine-disrupting chemicals is that we know they interact with human systems at very low levels,” says Miriam Rotkin-Ellman, a staff scientist at the Natural Resources Defense Council.

Fracking involves injecting a mixture of water, sand and chemicals deep below the earth to crack open rock formations. Many concerns over fracking center on the unknown effects of the chemical ingredients of the fluid used -- and whether any of those constituents could be EDCs.

University of Missouri researcher Susan Nagel and colleagues took samples from 29 “drilling-dense” areas in Colorado and three control sites in Missouri and Colorado with no or little drilling. The drilling sites all experienced some sort of spill in the last six years, ranging from leaks in pipes containing wastewater and chemical mixtures, water tank spills, improperly disposed wastewater and natural gas upwellings. The researchers ran the samples through a battery of tests using human cells, to see how chemicals in the water might interfere or interact with hormone signaling. They released their findings in a report published on Monday in the journal Endocrinology.

“The majority of water samples collected from sites in a drilling-dense region of Colorado exhibited more estrogenic, anti-estrogenic, or anti-androgenic activities than reference sites with limited nearby drilling operations,” Nagel and colleagues wrote.

Industry groups were quick to respond forcefully.

“Activists promote a lot of bad science and shoddy research, but this study -- if you can even call it that -- may be the worst yet,” Steve Everley of Energy In Depth, an arm of the Independent Petroleum Association of America, said in an emailed statement.

Pro-fracking groups say Nagel and her team stacked the deck by choosing sample sites that were either beset by recent spills, or free of drilling altogether. Missing from the equation is a portrait of what the water is like near drilling sites that are free of spills.

“We all know spills are bad and can cause problems, so what exactly did they expect to find?” Everley’s colleague Katie Brown wrote in a blog post for EID. “If this were about advancing the state of knowledge about the risks of development, the study would have focused on areas with oil and gas development where no known incidents had occurred. That might actually tell us something relevant about safety, since it would help determine if there are any unknown impacts that we should take care to safeguard against.”

But Nagel says spills are specifically what the research team was interested in assessing, since they are one of the pathways by which fracking fluids can contaminate surface and groundwaters.

“The sites were specifically chosen to assess whether fracking-related spills result in increased endocrine disrupting activity in surface and ground water,” Nagel wrote in an email. “As to whether we would have found different results at non-spill sites, impossible to say, but that was not the research question.”

Nagel’s coauthor, Christopher Kassotis, says that spills are a persistent problem in natural gas extraction.

“Spills related to fracking operations are widespread,” Kassotis wrote in an email. “Colorado has more than 500 reported oil/gas related spills in 2013 alone. Surface spills of chemicals are frequent occurrences in drilling-dense areas and may represent more of the 'norm' than the exception.”

Both the research team and industry groups say there’s a chance that some of the EDCs found in the samples could have come from sources besides fracking -- nearby farms, perhaps, or from trash leaching chemicals into the water. The study does not state that fracking has contaminated surface and groundwater in Colorado, but shows that EDC activity is greater in areas near spill sites.

Nagel’s team and pro-fracking groups also disagree on just how regulated fracking is.

The study from Nagel and colleagues “rehashes a favorite anti-fracking talking point that has been thoroughly discredited: the idea that oil and gas producers are somehow exempt from federal laws,” Brown at EID wrote.

While a recent study from the Government Accountability Office [PDF] notes that eight federal regulations apply to “unconventional oil and gas development” techniques like fracking, it also notes that “key exemptions or limitations in regulatory coverage affect the applicability of six of these environmental and public health laws.”

For example, an exemption added to the Safe Water Drinking Act, one of the key regulations underpinning the U.S. Environmental Protection Agency’s authority to regulate drinking water sources, specifically excludes hydraulic fracturing from its underground injection control program. While this and other exemptions do not limit the EPA’s ability to respond to contamination from fracking, they do limit the agency’s ability to enact certain preventative measures.

Another lingering issue in fracking is the question of just what chemicals are being used in the fracking fluid injected under the earth. Many companies voluntarily provide information on drilling operations, including the components of the fracking fluid used at specific wells on the FracFocus database. But not all states require companies to disclose the chemicals they use. FracFocus was also criticized in a report from Harvard Law School researchers earlier this year; the authors say the database lacks state-specific guidelines, gives too much allowance to trade secret guidelines that can mask specific ingredients, and allows drillers to enter incorrect information.

An individual drilling site may only use fracking fluid with less than a dozen ingredients (water and sand are usually the primary components). However, there are around 750 different chemicals employed in fracking across the industry as a whole, according to an April 2011 report from the Democrats on the U.S. House of Representatives Committee on Energy and Commerce [PDF].

“The job of protecting public health requires that we act to limit exposures to things in the environment that could harm human health,” the NRDC’s Rotkin-Ellman says.

SOURCE: Kassotis et al. “Estrogen and Androgen Receptor Activities of Hydraulic Fracturing chemicals and Surface and Ground Water in a Drilling-Dense Region.” Endocrinology published online 16 December 2013.