Hyraulic fracturing is a process that's used in nine out of 10 natural gas wells in the United States in which millions of gallons of water, sand and chemicals are pumped underground to break apart rock and release gas. Over the years, fracking has become a particularly controversial issue due to environmental concerns. However, a recent study also shows that several of the chemicals used in hydraulic fracturing could pose a danger to the body's hormones and potentially cause infertility.

"More than 700 chemicals are used in the fracking process, and many of them disturb hormone function," said lead study author Susan C. Nagel, Ph.D. of the University of Missouri School of Medicine, via a press release. "With fracking on the rise, populations may face greater health risks from increased endocrine-disrupting chemical exposure."

For the study, researchers analyzed 12 chemicals that were either known or suspected to be used in fracking. The chemicals are often grouped as endocrine-disrupting chemicals (EDCs) that can disrupt the normal function of the endocrine system. Exposure to the EDCs has also been linked to such health problems as cancer, birth defects and even infertility.

Thus, study researchers looked at how ECDs affect male and female hormones. To do this, researchers gathered data from surface and ground water samples via drilling spills or accidents in Garfield County, Co. and from drilling-sparse areas without spills in the same county and Boone, County, Mo.

Researchers note that the samples gathered from the drilling spill sites contained more EDC activity than samples from the control sites without drilling spills. They found that the high levels of EDC appear to affect how the human body reacts to androgens.

"Fracking is exempt from federal regulations to protect water quality, but spills associated with natural gas drilling can contaminate surface, ground and drinking water," Nagel said, via the release. "We found more endocrine-disrupting activity in the water close to drilling locations that had experienced spills than at control sites. This could raise the risk of reproductive, metabolic, neurological and other diseases, especially in children who are exposed to EDCs."

More information regarding the study can be found via the journal Endocrinology.