Twelve chemicals used in hydraulic fracturing or “fracking” operations to extract natural gas all showed endocrine-disrupting chemical (EDC) activity in laboratory cell studies, researchers report.
Moreover, surface and ground water samples from sites near spills at controversial drilling operations contained higher levels of the 12 EDCs than samples from control sites.
“While these chemicals were selected because of their suspected or known EDC activity, very few had been shown to have direct receptor activity,” the researchers write."Thus, this is the first demonstration of antiestrogenic or antiandrogenic activity for most of these chemicals."
The surface and ground water samples from “sites that have experienced some kind of spill related to natural gas drilling had on average about two-times the endocrine-disrupting activity than [samples from] sites that had not experienced a spill,” senior author Susan C. Nagel, PhD, University of Missouri School of Medicine, Columbia, told Medscape Medical News.
“The use of [hydraulic fracturing] has dramatically increased over the last 20 years,” and the number of natural gas wells in Colorado has increased almost 10-fold, Dr. Nagel said. Importantly, in 2005, hydraulic fracturing was exempted from multiple federal-regulatory acts including the Safe Drinking Water Act, Clean Water Act, and Clean Air Act.
Hormonal activity was measured using a gene assay in human cell lines.
Of the 12 chemicals analyzed, 1 (bisphenol A) exhibited estrogenic activity, 11 had antiestrogenic activity, 10 had antiandrogenic activity, and none had androgenic activity. To the researchers’ knowledge, this is the first report of antiestrogenic activity of 10 chemicals, including 3 types of ethylene glycol, as well as novel antiandrogenic activity in 6 chemicals, including naphthalene.
In the second part of the analysis, of 39 unique water samples, 89% exhibited estrogenic activity, 41% exhibited antiestrogenic activity, 12% exhibited androgenic activity, and 46% exhibited antiandrogenic activity.
Moderate-to-high estrogen- or androgen-receptor activities were measured in water samples from the Garfield County spill sites. Moderate-activity levels were also measured in samples collected from the Colorado River, the drainage basin for the region. In contrast, very little receptor activity was measured in water samples where there was no or sparse drilling.
“We identified EDC activity of several individual chemical components used in natural gas operations that may contribute to the activity that we measured in water,” the researchers summarize. They call for more impact studies: “There is evidence that hydraulic fracturing fluids are associated with negative health outcomes, and there is a critical need to quickly and thoroughly evaluate the overall human and environmental health impact of this process.”