Study: Potential for Fracking Chemicals to Disrupt Hormones

“Chemicals used in fracking could cause infertility, cancer and birth defects,” the Daily Mail has reported.

Cartoon picture of well on house propertyThe story comes from a study that examined whether 12 of the chemicals used in “fracking” (a method of gas and oil extraction) can disrupt the action of human sex hormones.

The study also looked at hormone-disrupting properties in water samples taken from fracking-dense sites in the US and compared them with samples of water taken from sites where fracking is sparse or non-existent.

Researchers found that the 12 chemicals tested all disrupted the activity of both female and male sex hormones. It also found that water taken from “fracking regions” had higher levels of hormone-disrupting activity than water taken from non-fracking areas.

What is ‘fracking’?

Fracking is the process of drilling and injecting water and chemicals into the ground at high pressure to fracture shale rocks and release natural gas and oil.

This fracking process can contaminate the water supply, as the BBC reported on US research earlier this year. This contaminated water could have an effect on the plant and animal life in the environment, as well as a potential effect on human health.

Some experts say the risk to public health is very small if fracking is carried out properly. These endocrine-disrupting chemicals are already found in the environment, but at certain levels they can interfere with human hormones.

The study’s findings are of concern, but inconclusive. We can’t currently say that if these endocrine-disrupting chemicals leach into water supplies they will end up being consumed by people in quantities that will cause damage. Further research is needed on this important issue.

Where did the story come from?

The study was carried out by researchers from the University of Missouri and the US Geological Survey Columbia Environmental Research Center, and was funded by the Passport Foundation Science Innovation Fund, the University of Missouri and the US Environmental Protection Agency.

It was published in the peer-reviewed journal, Endocrinology.

It was covered fairly by the Mail, although its headline linking chemicals to health problems such as infertility was potentially alarmist. The paper should be commended, however, for including comments on the potential health risks of fracking from Public Health England, a government agency with a remit to improve public health.

What kind of research was this?

This was laboratory research that tested some of the chemicals used in fracking for hormone-disrupting activity and also looked at hormone-disrupting activity in water taken from fracking sites and non-drilling areas. It did not examine the presence of these chemicals in humans or look directly at the potential health risks posed by fracking to humans.

The researchers say that hundreds of synthetic and naturally occurring chemicals have the ability to disrupt normal hormone action. They are called endocrine-disrupting chemicals (EDCs) – a group that includes Bisphenol A (BPA), which regularly features in news reports.

They say that laboratory experiments have shown a wide range of effects from such chemicals at low concentrations of the level found in the environment. They have been linked to a number of health problems in humans, including cancer and reproductive problems.

The researchers say a potentially new source of EDCs in the environment is from hydraulic fracturing operations for natural gas or oil extraction. This involves the high pressure underground injection of a combination of millions of gallons of water and chemicals into each well. They say that more than 750 chemicals are reportedly used throughout this process, of which more than 100 are known or suspected endocrine disrupters, while others are toxins or carcinogens.

The rapid expansion in fracking increases the potential for contamination of the water supply with the hundreds of hazardous chemicals, they argue.

The endocrine system can be disrupted by EDCs in a number of ways:

  • Anti-oestrogenic (estrogenic*) activity, which suppresses the activity of the female sex hormone oestrogen (estrogen*)
  • Anti-androgenic activity, which suppresses the activity of male sex hormones, including testosterone
  • Oestrogenic activity, which promotes or mimics the activity of oestrogen
  • Androgenic activity, which promotes or mimics the activity of male sex hormones

What did the research involve?

The authors first examined 12 suspected or known endocrine-disrupting chemicals among the many used in fracking operations. In the laboratory, they measured the chemicals’ ability to mimic or block the effects of the body’s male and female sex hormones.

They also collected a total of 39 ground and surface samples of water from different regions in the US:

  • “Drilling-dense” sites in Garfield County, Colorado, which have experienced spills or accidents – this is an area with more than 10,000 natural gas wells
  • Sites in the same county where drilling was limited, and sites in Boone County, Missouri, which have no natural gas drilling
  • Several sites along the Colorado River, which is the drainage basin for the natural gas drilling sites

The samples were tested for the activity of endocrine-disrupting chemicals, although it is unclear how this was performed.

What were the basic results?

The researchers found that the 12 natural gas drilling chemicals tested had a variety anti-oestrogenic (estrogenic*), anti-androgenic and limited oestrogenic activity, including:

  • Of the 39 unique water samples taken, overall they found that 89% exhibited oestrogenic (estrogenic*) activity, 41% exhibited anti-oestrogenic activity, 12% exhibited androgenic activity, and 46% exhibited anti-androgenic activity
  • The water samples taken from drilling dense sites exhibited more oestrogenic, anti-oestrogenic and anti-androgenic activity than sites with limited or no drilling operations
  • Samples from the Colorado River exhibited moderate levels of oestrogenic, anti-oestrogenic and anti-androgenic activity

How did the researchers interpret the results?

The researchers say their data suggests that natural gas drilling operations may result in increased activity of endocrine-disrupting chemicals in surface and ground water.

Exposure to EDCs, they say, has been linked to several health problems in laboratory animals, wildlife and humans.


This study found that 12 chemicals used in fracking in the US exhibited endocrine-disrupting activity. It also found that surface and ground water taken from sites where fracking occurred had higher levels of endocrine-disrupting activity than other samples from non-fracking areas.

The results of this study are of concern, but are inconclusive. In particular, the researchers did not directly measure the presence of EDCs in the water samples taken, and it was not certain whether the levels of activity found would be hazardous to public health. And areas where there had been spills and accidents might be expected to have contaminated water supplies.

In the US, reportedly, waste water from fracking is stored in open pits and fracking is exempt from regulations on water quality. Some health experts in the UK say that the risk to public health is low if fracking is properly regulated. Further research is needed on this issue.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.


“Chemicals used in fracking could cause infertility, cancer and birth defects,” the Daily Mail has reported. The story comes from a study that examined whether 12 of the chemicals used in “fracking”…

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* Editor’s Note: clarification provided by Pediatric Safety for U.S. readers

About the Author

NHS Choices ( is the UK’s biggest health website. It provides a comprehensive health information service to help put you in control of your healthcare.


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