HealthDay News — The majority of surface and ground water samples collected from sites in a natural gas drilling-dense region of Colorado had higher levels of estrogenic, anti-estrogenic or anti-androgenic activities than control sites with limited nearby drilling operations, researchers found.

Susan C. Nagel, PhD, of the University of Missouri in Columbia, and colleagues collected water samples in the drilling-dense region of Garfield County, Colo. The samples then underwent solid-phase extraction and were measured for estrogen and androgen receptor activities using reporter gene assays in human cell lines.

The researchers sought to measure the estrogenic, anti-estrogenic, androgenic and anti-androgenic activities of 12 suspected or known endocrine-disrupting chemicals (EDCs) used in the controversial natural gas drilling process, known as fracking. They then compared these activities in surface and ground water from fracking and nonfracking sites. The results were published in Endocrinology.

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In the chemical analysis of the subset of natural gas drilling chemicals, novel anti-estrogenic, novel anti-androgenic and limited estrogenic activities were observed. No androgenic activity was observed.

Water samples were collected from ground, surface and artisan water sources in September of 2010 from five distinct sites with 43 to 136 natural gas wells within one mile and a spill or incident related to natural gas drilling occurring within the previous 6 years.

Surface water samples were also collected from the Colorado River, which is the drainage basin for this drilling-dense region. Control water samples were collected in areas without drilling from Boone County, Mo. and in areas with little drilling in Garfield County.

Water samples from drilling sites that experienced fracking spills or accidents showed moderate to high levels of EDC activity, while samples from sites with little drilling showed very little activity, the researchers found.

There were also moderate levels of estrogenic, anti-estrogenic and anti-androgenic activities in testing of the Colorado River, the drainage basin for this region, whereas Missouri reference sites exhibited low estrogenic, very low anti-estrogenic and no anti-androgenic activities:

  • Ground water samples collected from three of the drilling-dense sites exhibited higher estrogenic activities than both Garfield County and Missouri control samples (P<0.0001)
  • Anti-estrogenic activity was observed in surface water at four drilling-dense sites and in Colorado River samples, while little to no anti-estrogenic activity was observed in Garfield County or Missouri control sites
  • Surface water samples collected from three drilling sites displayed greater anti-androgenic activity than Missouri reference sites (P<0.05), and surface water samples collected from the Colorado River displayed intermediate anti-androgenic activity that did not differ from the drilling sites but were significantly greater than the Missouri reference sites (P<0.05)

The findings suggest that higher localized activity at sites with known natural gas-related spills surrounding the river might be contributing to the multiple receptor activities observed in the Colorado River drainage basin, according to the researchers.

“Our data suggest that natural gas drilling operations may result in elevated endocrine disrupting chemical activity in surface and ground water,” the researchers concluded.

Study limitations included a lack of direct identification of fracking chemicals in the tested water, the researchers acknowledged. They called for more comprehensive sampling of drilling sites in Garfield County to determine whether natural gas drilling is contributing to elevated EDC activity in ground and surface water.


  1. Nagel SC et al. Endocrin. 2013; doi:10.1210/en.2013-1697.