Susan Nagel explores links between fracking and endocrine disruption

By Caleb O’Brien

COLUMBIA, Mo. — It was a warm, crystalline day in Garfield County, Colo., in September 2010. Susan Nagel stood in a stream with an amber glass bottle clutched in her hand. She bent and plunged the empty vessel below the water’s surface. Twice she filled the bottle, and twice she turned and emptied it again into the stream. After filling the bottle a third time, she screwed a cap onto its narrow mouth and tucked it into a cooler full of ice.

Susan Nagel studies reproductive biology and hormones. Photo by Caleb O'Brien

Susan Nagel studies reproductive biology and hormones. Photo by Caleb O’Brien

Upstream, a beaver dam spread the stream’s waters into a pool; in the distance rose a natural gas well. As Nagel walked away, the stream chucked and sighed behind her, bearing its freight of water and chemicals down towards the Colorado River.

Nagel brought that water sample and others back to her laboratory in Columbia, Mo. It was the beginning of a multi-year endeavor spurred by the explosion of hydraulic fracking for natural gas and unresolved questions about the technique’s impact on health and the environment.

Nagel’s lab is on the sixth floor of the University of Missouri’s Medical Sciences Building, an aging beige structure nestled among the school’s health sciences buildings. Nagel, an associate professor of Obstetrics, Gynecology and Women’s Health, studies hormones and endocrine-disrupting chemicals. Her research on sex hormones and reproductive biology takes place at the confluence of ongoing debates about regulatory policy in the United States and underscores the gulf between endocrinology’s emphasis on the functions and disorders of the endocrine system and toxicology’s focus on poisons and their effects.

A delicate balance

The endocrine system is the body’s tool for talking with itself. It is composed of a handful of glands that release hormones — chemical messengers that travel throughout the body — and orchestrate processes such as growth, metabolism, mood and sexual maturation. When the endocrine system becomes unbalanced or disturbed, the body loses its ability to effectively regulate itself and a whole host of problems and diseases may ensue.

In the past several decades, scientists have discovered that some chemicals from outside the body can interfere with the function of the endocrine system. Called endocrine-disrupting chemicals, or EDCs, these substances can mimic the hormones released by the body’s glands or prevent the body’s receptors from reading the messages carried by its own hormones. These chemicals may upset the delicate balance of the endocrine system even at extremely low doses. They can be synthetically produced by humans or — like phytoestrogens in soy plants — found naturally in the environment.

One such endocrine-disrupting chemical is Bisphenol-A, or BPA. It is an industrial chemical widely used in the production of plastics and resins and can be found in everything from water bottles to the lining of food cans.

As a graduate student at MU, Nagel helped conduct research linking BPA to enlarged prostates and decreased sperm counts in mice exposed as fetuses to the chemical. Nagel’s advisor at the time, Frederick vom Saal, is a prominent endocrine disruption researcher. He has often told a story about chemical industry representatives asking him to seek industry approval before publishing the initial study on BPA in exchange for a nebulous “mutually beneficial outcome.”

Nagel’s experience studying BPA  with vom Saal would radically change the trajectory of her career.

The making of a scientist

Susan Nagel hadn’t always wanted to be a biologist. She was a sophomore majoring in business at Hendrix College in Conway, Ark., when she took a course in biology for non-majors. The class, coupled with the experience of rearing a tadpole in her dorm room, kindled her interest in biology.

She graduated from Hendrix with a degree in biology in 1991 and two years later began graduate work at the University of Missouri. Although she was initially interested in animal behavior, Nagel quickly became caught up in the controversial world of endocrine disruption when vom Saal asked her to help develop an assay to study the way BPA is carried in the blood. He told Nagel the project would only take a couple months, she says. It took years.

When their paper linking BPA to endocrine disruption was published, it was a bombshell and elicited a great deal of attention and scrutiny. The experience of wading into such controversial waters so early in her career was overwhelming, Nagel says.

“It kind of took a while for me to recover from all that,” she says. “But it is a deep interest of mine, so I am now more willing to at least ask those questions.”

During her postdoc at Duke, Nagel continued to study the endocrine system. Working with Donald McDonnell, a professor in the Department of Pharmacology and Cancer Biology, she developed a mouse model capable of detecting estrogen disruption.

McDonnell says Nagel is a scrupulous, passionate scientist and a dedicated mentor to young researchers.

“Before she came to my lab, she was already recognized as a leader in molecular toxicology,” he says. Her time spent working with McDonnell equipped Nagel with a higher-resolution arsenal of techniques to investigate problems, he says.

Theo Colborn, whose 1996 book, “Our Stolen Future,” brought endocrine disruption to the attention of the nation, says Nagel’s experience and expertise allow her to effectively translate laboratory discoveries to what is happening in the environment and in society. Colborn conducted groundbreaking research into endocrine disruption in wildlife around the Great Lakes and founded the Endocrine Disruption Exchange, a Colorado-based environmental organization.

“She has an open mind and can work beautifully across disciplines,” Colborn says.

Nagel herself is pragmatic about her motives. She sees a tremendous gap in our knowledge of endocrine-disrupting chemicals and feels compelled to continue her research despite the challenges.

“No one else is going to do that,” Nagel says. “It’s never going to be popular or financially a good choice… It’s something that I see that needs to be done.”

Hydraulic fracking

The cover of Enocrinology showing well sites and the locations where Nagel and her team collected water samples.

The cover of Enocrinology showing well sites and the locations where Nagel and her team collected water samples. Image courtesy of Susan Nagel

Hydraulic fracturing is a technique wherein water and other fluids are injected underground. When combined with horizontal drilling, fracking has expanded access to previously inaccessible natural gas reserves. As a result, in recent years natural gas production has reached levels not seen in the US for decades. Concern about the environmental impact of fracking has grown as the process has become ubiquitous.

A 2011 report from the House of Representatives Committee on Energy and Commerce found that fracking utilizes up to 750 different types of chemicals during the process. A 2010 paper by Theo Colborn found that more than 100 of those chemicals are known or suspected endocrine disruptors. Of the remaining chemicals, some are toxic, some pollutants and some entirely innocuous. They serve a broad array of functions, from reducing friction during drilling to acting as antibiotics or thickening agents.

The link between endocrine-disrupting chemicals and fracking piqued Nagel’s interest, and she began developing a preliminary, two-pronged experiment to examine some of those chemicals. Her team of scientists tested the endocrine-disrupting effects of 12 of the chemicals identified in the 2011 report. The scientists did so by measuring the chemicals’ effect on estrogen and androgen receptors spliced into human cancer cells and grown in their lab.

“Androgen and estrogen are the two sex hormones,” says Christopher Kassotis, a graduate student in Nagel’s lab. “They’re responsible for a lot of things, but importantly, normal development, normal sexual maturation.” Kassotis, who holds first authorship on their study, joined Nagel’s lab around the time Nagel began looking into fracking chemicals. Much of Nagel’s research has focused on those two hormones and the chemicals that can mimic them or disrupt their function, so her lab was well equipped for the study.

In September of 2010, Nagel and a former graduate student named Annette Hormann travelled to Garfield County, Colo., to collect samples of ground and surface water. The five sample sites were within the Colorado River Drainage Basin and the Piceance Shale Basin, and were selected by Nagel with assistance from Colborn and the Endocrine Disruption Exchange. Garfield County boasts a tremendous number of natural gas wells: one site where they collected water was within one mile of 136 wells.

Nagel and Hormann also met with the landowners whose water they tested.

“These people, four of the five, had experienced something really dramatic,” Nagel says. Each knew the “real frustration of getting cleanup and responsibility,” and had experienced the economic repercussions of the incidents.

One of the sites had been a small ranch before a fracking water spill occurred. Afterwards, the rancher quit because his animals stopped bearing live offspring, Nagel says. Another landowner, who ran a business taking hunters out to bag big game on his land, quit after a fracking-related incident because of concern that the animals’ meat would be contaminated.

Back in Nagel’s lab in Columbia, the scientists tested the water for its ability either to mimic or block estrogens and androgens using the same procedure they’d used for the 12 fracking chemicals. The five samples all came from areas that had recently experienced spills or incidents and were within close proximity to numerous wells. For comparison, Nagel also tested water samples from the Colorado River, from areas in Garfield County with far fewer wells and from central Missouri.

After conducting the experiment and passing the results off to MU biostatistician Wade Davis, the team found that the 12 fracking chemicals they tested exhibited endocrine disrupting effects. The chemicals mostly blocked estrogen and androgen, although one had some estrogen-mimicking effects as well. The most potent estrogen blocking chemicals were 2-ehtyl-1-hexanol and ethylene glycol, whereas cumene, n,n-dimethylformamide and ethylene glycol most strongly blocked androgen. The scientists found estrogenic activity activity for bisphenol A.

Similarly, they found that many water samples from the five sites that had experienced a drilling-related incident had more estrogen- and androgen-blocking as well as estrogen-mimicking effects than samples collected elsewhere.

Nagel’s research did not identify the individual chemicals that were contained in the water samples or attempt to track how the chemicals got there. But she believes the study results, when considered with other scientists’ research, suggests a correlation between natural gas drilling and endocrine-disrupting chemicals in nearby water.

A complicated subject

Nagel’s research on endocrine disruption tackles complex biological processes that have challenged scientists and regulators alike.

Jane McElroy is an environmental epidemiologist who works a few floors below Nagel’s lab. She and Nagel will be collaborating on a new phase of research into EDCs and fracking.

“What’s been a problem for quite some time in environmental research is that no one lives in a world where there’s just one chemical exposure,” she says. “It’s always this hodgepodge of stuff that you’re exposed to.” Scientists have uncovered many of the smoking guns, she says: chemicals like benzene, lead and mercury that are demonstrably dangerous. But it’s far more complicated and expensive to parse the effects of the many minute exposures people experience in the real world.

Endocrine-disrupting chemicals escaped the attention of government regulators for many years, Nagel says. She views the current system of staffing federal advisory committees with stakeholders as favoring the status quo and inclined to conclude that chemicals are not harmful. She contrasts this system with the precautionary principle, a regulatory philosophy under which chemicals must be proven safe before they can be used.

Hydraulic fracking, for example, was exempted from parts of the Safe Drinking Water Act, according to the 2011report.

“Our legal system requires the burden of proof to be on the individual affected by the environmental exposure,” McElroy says.

The differences between the fields of toxicologists and endocrinologists also figure into competing beliefs about endocrine disruption. Endocrinologists study chemicals and hormones that may actually have a greater hormonal effect at extremely minute concentrations than at significantly higher doses. Toxicologists, in contrast, have traditionally held the view that “the dose makes the poison,” or that chemicals harmful at high doses can be benign at lower ones.

Kassotis says BPA is one of the chemicals that highlights the disconnect between toxicology and endocrinology. “The FDA has been relying on these toxicological studies that say ‘we give BPA at high doses and nothing bad happens’ and endocrinologists are like ‘but you’re not looking at doses that actually do something,’” he says.

However, the distance between the two fields may gradually be lessening. Nagel cites a recent meeting between officials from the EPA and the Endocrine Society — an organization dedicated to hormone research and clinical endocrinology — as a tremendous step towards reconciling the two fields. Mcdonnell also thinks the fields have begun to converge as they have increasingly turned to the same molecular techniques of discovery and analysis.

They have not yet reconciled all their differences, however. An FDA study recently published in the journal Toxicological Sciences found no low-dose effects of BPA on rodents. Nagel and other scientists have questioned the study’s validity. The FDA team was unable to keep the control group from being contaminated with BPA and the level of assessment for endocrine-disrupting effects employed in the study may have been too crude to pick up differences between the groups, Nagel says.

But Nagel’s goal in this complicated environment is straightforward: do the research. She continues to find the complexity of the natural world deeply fascinating and takes great pleasure in charting the blank spaces on the map of human knowledge. Her lab is repeating the experiment with twice the chemicals and three additional hormones. They’re looking for endocrine disruption in mice that consume fracking chemicals in their drinking water and they’re beginning to delve into identifying the endocrine-disrupting chemicals they found in the Garfield County water samples. With McElroy, they’ll begin preliminary research focused on the people of Garfield County and the ways hydraulic fracking has impacted their lives. Nagel recently launched a crowdfunding campaign to raise funds to continue her team’s efforts.

“We can be passive, and just say, ‘Well the world is polluted and there are exposures and oh well,’ or we can try to have a better understanding of what pollutants may be important,” McElroy says.

Colborn likens Nagel’s work with endocrine disruption and fracking to the research on endocrine disruption in wildlife Colborn conducted years ago.

“She’s in the predicament I was in where she’s found something and just can’t stop,” Colborn says. “She’s made a breakthrough and she’s going to be a pioneer in this field.”

Updated 5/14/2014


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