Hydraulic fracturing, also known as fracking, is the process of extracting natural gas from rock formations buried beneath the earth using water, sand, and chemicals at very high pressure. The mere mention of this controversial method is likely to set off a heated debate.

Hydrofracking's fans claim that permitting widespread fracking can help us become less dependent on foreign oil. Opponents say the fracking process is not only wasteful, but is also hazardous both to the environment and those who live around drilling sites.

Water samples from sites in Colorado and Missouri with little drilling had far less evidence of endocrine-disrupting compounds compared to samples collected in drilling-dense regions of Colorado.

Opponents of fracking have some more evidence for their argument, courtesy of a newly published study. The researchers report that the chemicals used in fracking often contain endocrine disrupting chemicals, or EDCs: they act on the hormone receptors of cells, and interfere with their proper function.

But the real cause for concern is that these potentially dangerous chemicals may be found in the ground water in areas where a lot of drilling is taking place.

“It was a little surprising that so many [more than 700] chemicals are used in hydraulic fracturing,” Susan Nagel, an author of the study, told The Doctor.

Because the specifics of the fracking process is proprietary — natural gas producers do not have to disclose what chemicals they are using — it is especially challenging for scientists to assess its effects.

But, Nagle, an associate professor of obstetrics and gynecology and women’s health at the University of Missouri, added, “Knowing what I know about endocrine disruption, I was not all that surprised that some fracking chemicals are endocrine disruptors.”

Endocrine disrupters have been linked to infertility and birth defects, among other health problems and are often found in pesticides.

Nagel's team took samples of surface and ground water around Garfield, Colorado, an area with a lot of fracking activity. Almost 90 percent of the 39 different water samples showed some form of endocrine disrupting activity.

To determine if fracking was the source of the problem, the investigators also tested a group of the chemicals used in hydraulic fracturing and found that they, too, exhibited the same endocrine-disrupting activity.

Water samples from sites in Colorado and Missouri with little drilling had far less evidence of endocrine-disrupting compounds compared to samples collected in drilling-dense regions of Colorado.

“People have enough to worry about as it is. But as a society and a country, I think [the risk of introducing endocrine disrupting chemicals through fracking] is something that we should absolutely look into further,” Nagel said.

She and her team plan to investigate whether the incidence of possible human health consequences, such as cancer and preterm birth, is higher in drilling-dense areas compared to drilling-absent areas. They also expect to search for the presence of individual chemicals responsible for the endocrine disrupting activity.

The study is published online in Endocrinology.