A group of researchers whose previous flawed work claimed exposure to fracking fluid causes low sperm counts and ovarian follicle problems in mice has released yet another study claiming to find a link to endocrine disrupting chemicals (EDCs) in fracking fluid and potential health problems.

This latest study has a new and much more foreboding topline conclusion than the team’s other recent efforts — claiming “exposure to chemicals used during fracking may cause pre-cancerous lesions in mice” — but it is based on the same old flawed methodology and assumptions the researchers have repeatedly employed (read more about the three most prominent examples here, here and here).

It bears repeating that one of the lead researchers of this study and the aforementioned reports — University of Missouri obstetrics, gynecology and women’s health associate professor Susan Nagel — has not been shy about concealing her anti-fracking bias.

Nagel has previously appealed to anti-fracking activists Josh FoxMark Ruffalo and Yoko Ono to help fund her research. She has also publicly endorsed Gasland at an event entitled “What the Frack?”, calling Josh Fox’s thoroughly debunked films “educational” because they contain “a lot of good information.”

Perhaps prompted by growing awareness of Nagel’s anti-fracking activism, she is not listed as the lead author of the study. But the University of Missouri’s press release states that the study was conducted by “Susan Nagel and her team,” leaving no doubt as to who was in charge.

With that backdrop of activism from this research team’s quarterback established, it’s no surprise this latest effort offers more of the same.

Here are four things to know about this study and the research team responsible for it.

#1. Researchers use own debunked study to support claim of widespread exposure to fracking fluid

For this study, the researchers exposed female mice to a mixture of 23 known chemicals used in fracking fluid at four different concentration levels from “gestational day 11 to birth.”

Study co-author Laura Vandenberg claims in the study’s University of Massachusetts’ press release that, “These results are particularly interesting because they suggest harm from chemicals that have been poorly studied, but with likely widespread human exposures.” The press release goes on to claim “the two lower doses they used are equivalent to the concentrations measured in drinking water in regions experiencing drilling…”

But there is a huge problem these claims of widespread exposure via drinking water — they are based entirely on the Nagel team’s thoroughly debunked first hormone study, in which they claimed to have located EDCs from fracking in the water at a number of sites (check out EID’s debunk of that study here).

Since that study’s release, the researchers have been forced to admit that they had no scientific evidence to make any link between fracking and contamination at those sites. As Nagel stated last year in an NPR interview,

“We did not prove that those spills were the cause of the increased endocrine disrupting activity in the water.”

The Colorado Department of Public Health and Environment (CDPHE) agreed, sharing a series of criticisms against the paper with the media that included the following:

“There are numerous septic systems in Garfield County. We don’t know how this may influence endocrine-disrupting chemicals (EDCs) concentrations in groundwater.”

CDPHE also noted that the researchers’ geological assumptions were “not factually or scientifically valid” and “there is no indication in the study that any of the sample sites are currently used for drinking water.” The medical publication Clinical Advisor further noted “a lack of direct identification of fracking chemicals in the tested water.”

In other words, using this study to support the claim of widespread exposure to fracking fluids is weak at best.

And of course, the scientific community agrees that upward migration of fracking fluids from depth into water tables is extremely unlikely. Most notably, EPA’s five year study of fracking and groundwater — the most thorough study on fracking to date — concluded, “[H]ydraulic fracturing operations are unlikely to generate sufficient pressure to drive fluids into shallow drinking water zones.”

A 2013 Gradient study states clearly that “Overall, there is no scientific basis for significant upward migration of HF fluid or brine from formations in sedimentary basins…”

The EPA study also found “no documented impacts to groundwater” from spills related to the chemical mixing process. These are just two of the more than two dozen studies that have concluded fracking and related activities are not a serious threat to groundwater. Bottom line — there is no evidence to support these researchers’ that people are being exposed to fracking chemicals.

#2. Mice were exposed to high and disproportionate concentrations of fracking chemicals

This study uses the exact same dosage levels used in this team’s aforementioned studies that found low sperm counts and ovarian follicle problems in mice. As the study states:

“Female C57Bl/6 mice were exposed to approximately 3, 30, 300 or 3000 μg/kg/day UOG-MIX from gestational day 11 to birth.”

According to the press release on this new study, the researchers claim the exposure levels are “environmentally relevant” and that the “two lower doses they used are equivalent to the concentrations measured in drinking water in regions experiencing drilling.”

That’s an interesting claim, considering study co-author Christopher Kassotis admitted back in 2015 that it is “unlikely people would ever be exposed to doses quite as high” as the concentrations used in each of this team’s studies.

This latest Nagel/Kassotis study even acknowledges:

“It should be noted that concentrations for several of the 23 chemicals in the UOG-MIX used here have not yet been determined in either drinking water or wastewater.”

This admission echoes something else Kassotis said a few years back:

“Kassotis cautioned that they have not measured these chemicals in local water samples, and it is likely that the high chemical concentrations tested would not show up in drinking water near drilling.”

It is also worth noting that the researchers administered the 23 chemicals in an equimolar fashion — assuming all chemicals are used in equal proportions in the typical fracking fluid composition — which is by no means representative of reality.

More importantly, it can’t be emphasized enough that fracking fluid is typically 99.5 percent water and sand, while the remaining 0.5 percent is made up of additives.  According to that same EPA report, the maximum concentration of all additives was less than one percent and the median maximum fracking fluid concentration was 0.43 percent by mass.

Paracelsus said back in the 16th century that the “dose makes the poison” and that just about anything in high enough doses can be poisonous. And even then, an exposure pathway is necessary for a chemical to pose a danger. At this point, it is clear that the Nagel team is manipulating both dose and exposure data in an attempt to bolster its weak case that EDCs found in fracking fluid are an inherent harm to public health with this series of studies. There is simply no credible evidence to support their claims.

#3. Authors admit study does not provide evidence of link between fracking and breast cancer

Though the study has generated little mainstream media coverage, a handful of fringe anti-fracking media outlets have honed in on the following excerpt from the study’s press rollout as “evidence” the report links fracking to breast cancer.

“The authors believe theirs is the first study to show that mouse mammary gland tissues are sensitive to a mixture of 23 commonly used UOG chemicals, with dose-specific effects on tissue morphology, cell proliferation and induction of intraductal hyperplasias, an overgrowth of cells considered a marker for future breast cancer risk.”

But the researchers make it crystal clear that the study finds no such definitive link:

“The evidence for an association between UOG operations and breast cancer, or other diseases of the breast, remains inadequate. The results from our study suggest that longitudinal studies, evaluating women exposed to UOG chemical mixtures during early life, are needed to address this data gap.”

Though we continue to see this “more studies needed” language used when researchers with a clear anti-fracking bias don’t get the definitive smoking gun results they covet, it is at least a bit refreshing to see the authors clearly communicate their study does not represent a link between fracking and cancer.

#4. Chemicals identified as EDCs are in common products and nature

Even though it’s starting to sound like a broken record (EID has debunked six of this team’s EDC studies so far) it also bears repeating that this team’s own data show that many of the EDCs they analyzed are located in dyes, perfumes, plastics, personal care products, detergents, cleaning agents, and the list goes on.

Ten of the EDCs studied are naturally occurring, and six of these chemicals are also surfactants – chemicals what were recently found to be “no more toxic than common household substances” by a University of Colorado-Boulder report.

As stated earlier, the presence of EDCs is far less relevant than the essential context on dose and exposure that is manipulated by this study. It is far more likely that the average individual is exposed to these EDCs in their kitchen or garage than any oil and gas activity.


As we have stated before, this isn’t the first effort by these researchers to link fracking to hormonal issues, and unfortunately, it certainly won’t be the last. But as long as the researchers continue to churn out misleading studies based on inaccurate assumptions regarding exposure and chemical concentrations of fracking fluid, EID will continue to point out the researchers’ alarmist conclusions have no basis in reality.