University of Missouri researchers have found greater hormone-disrupting properties in water located near hydraulic fracturing drilling sites than in areas without drilling. The researchers also found that 11 chemicals commonly used in the controversial “fracking” method of drilling for oil and natural gas are endocrine disruptors.

Endocrine disruptors interfere with the body’s endocrine system, which controls numerous body functions with hormones such as the female hormone estrogen and the male hormone androgen. Exposure to endocrine-disrupting chemicals, such as those studied in the MU research, has been linked by other research to cancer, birth defects and infertility.

“More than 700 chemicals are used in the fracking process, and many of them disturb hormone function,” said Susan Nagel, PhD, associate professor of obstetrics, gynecology and women’s health at the MU School of Medicine. “With fracking on the rise, populations may face greater health risks from increased endocrine-disrupting chemical exposure.”

The study involved two parts. The research team performed laboratory tests of 12 suspected or known endocrine-disrupting chemicals used in hydraulic fracturing, and measured the chemicals’ ability to mimic or block the effects of the reproductive sex hormones estrogen and androgen. They found that 11 chemicals blocked estrogen hormones, 10 blocked androgen hormones and one mimicked estrogen.

The researchers also collected samples of ground and surface water from several sites, including:

• Accident sites in Garfield County, Colo., where hydraulic fracturing fluids had been spilled
• Nearby portions of the Colorado River, the major drainage source for the region
• Other parts of Garfield County, Colo., where there had been little drilling
• Parts of Boone County, Mo., which had experienced no natural gas drilling

The water samples from drilling sites demonstrated higher endocrine-disrupting activity that could interfere with the body’s response to androgen and estrogen hormones. Drilling site water samples had moderate-to-high levels of endocrine-disrupting activity, and samples from the Colorado River showed moderate levels. In comparison, the researchers measured low levels of endocrine-disrupting activity in the Garfield County, Colo., sites that experienced little drilling and the Boone County, Mo., sites with no drilling.

“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. “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 endocrine-disrupting chemicals.”

The study, “Estrogen and Androgen Receptor Activities of Hydraulic Fracturing Chemicals and Surface and Ground Water in a Drilling-Dense Region,” was published in the journal Endocrinology.