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Welcome to PSR's Environmental Health Policy Institute, where we ask questions -- then we ask the experts to answer them. Join us as physicians, health professionals, and environmental health experts share their ideas, inspiration, and analysis about toxic chemicals and environmental health policy.


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Animals as Sentinels of Human Health in Hydraulic Fracking

By Michelle Bamberger, MS, DVM and Robert Oswald, PhD

Although hydraulic fracturing of wells for extraction of hydrocarbons has been used for more than sixty years, newer methods involving high volumes of fluids and horizontal drilling have been introduced recently and represent a massive increase in the environmental footprint. First introduced into less populated areas of Colorado, Wyoming, Texas, and Alberta, Canada, these newer techniques raised poorly publicized environmental and health concerns. With expansion of high volume hydraulic fracturing into populated areas of the Northeast, the process has come under intense scrutiny. We are studying the effects of hydraulic fracturing on human and animal health, as well as impacts on food safety.1 Animals can be used as sentinels of human health because of more frequent exposure to air, soil, and groundwater and more frequent reproductive cycles.

Consider the effect of a water contamination event on reproductive health. The number of pregnant women exposed to contamination from one gas well would be small even in the most populated areas. However, a herd of cows in a contaminated pasture provides many pregnant females for study. The question is how to determine if a link exists between drilling with high-volume hydraulic fracturing and public health. Considering the normal progression of studies on a particular disease (e.g., the AIDS epidemic), research often begins with case reports (reports of gay men with Karposi’s sarcoma for the AIDS epidemic2), followed by epidemiology, studies of cause-and-effect, and development of treatment options. Case studies provide a view of potential exposure pathways and can guide further epidemiological work, and thus, we have begun with case studies.

We have conducted in-depth interviews with over 30 animal owners concerning their health as well as the health of their animals from five years prior to drilling to the time of the interview. We reviewed medical records, environmental sampling results, and spoke to veterinarians and other medical professionals where possible. The most common health impact in animals was reproductive failure (abortions, stillbirths, irregular cycles and failure to breed). This was particularly evident in three cases of cattle, in which the herd was split into two or more pastures. Those cows exposed to drilling wastewater or contaminated well water experienced reproductive impacts, while those not exposed showed no unusual health problems. Despite the fact that these studies had de facto control and experimental groups, making a firm correlation between exposure to specific chemicals and a particular health outcome was difficult due to lack of appropriate testing before and after exposure. Among humans in our study, the most commonly reported health problems were burning of the eyes, nose and throat; headaches; nosebleeds; rashes; vomiting and diarrhea.

Further studies are needed to determine the prevalence of these problems; nevertheless, we have identified several issues that are of concern:

(1) Nondisclosure agreements: Cases of health impacts have been shielded from further study by legal agreements that tied victim compensation to agreement not to disclose information about the case. These agreements prevent study of the cases and also make studies of prevalence more difficult. A second type of nondisclosure agreement (now mandated in Pennsylvania and soon to be mandated in Ohio) requires a physician to sign a nondisclosure agreement in order to obtain the identity of drilling chemicals that may have harmed a patient. This hampers free exchange of information among physicians and between physicians and patients, and hinders further research. Nondisclosure agreements in issues of public health should be banned.

(2) Food safety: Animals exposed to drilling wastewater or contaminated water are not required to be tested before slaughter. In one case that we studied, exposed cattle were quarantined for a period of time before slaughter, but the holding times were, at best, educated guesses. Also, cattle that die before going to slaughter, are debilitated, diseased, or cannot walk into the slaughterhouse are sacrificed and the flesh is sent to rendering plants. The product of these plants is made into animal feed (e.g., for chickens, swine and pets) and any contamination can find its way into our food supply. We need to have better regulation of food animals exposed to drilling fluids and waste, contaminated water, air or soil, and hydraulic fracturing fluids.

(3) Routes of exposure: We identified many sources of exposure to drilling by-products. By far, the most common exposure was to contaminated well or spring water, but animals were also exposed to wastewater (leaking impoundments, spreading on roads, and dumping into surface waters) and air contamination (pipeline rupture, well flaring, compressor station malfunction). To understand health effects associated with drilling, it is important to consider the entire lifecycle of a well from the initial drilling to the final capping and retirement of the well.

(4) Testing: While taking the step of predrilling testing is easy to suggest, deciding on the chemicals to be tested3 and interpretation of the results are not simple tasks. Clearly, predrilling testing of water, air and soil should be done for all components of the drilling mud and hydraulic fracturing fluids. Chemicals used (excluding those considered trade secrets) are disclosed by the industry to the public only after completion and on a voluntary basis ( This precludes using this information for predrilling testing. Secondly, the wastewater contains chemicals from the shale (heavy metals, radioactive material, organics) that can be as toxic or more toxic than the hydraulic fracturing fluid. Predicting exactly what will be in the wastewater can be problematic.

Interpreting the testing results is an equally difficult issue. Typically, maximum contaminant levels (MCLs) are used to determine if a chemical poses a risk in water. Particularly in the case of endocrine disruptors, the concentration profile of toxic effects may not be monotonic, with lower doses having potentially more toxic effects than higher doses.4 MCLs do not take into account low-dose effects, nor do they reflect the challenge of understanding the cumulative effects of exposure to multiple toxic chemicals. Without a better understanding of low-dose effects and mixtures, the interpretation of testing results may not take into consideration important risk factors.

The shale gas revolution is sweeping the world, with little or no assessment of the impacts on public health. Without better scientific studies that will help us understand the risks and balance of the risks with the benefits, our federal and state governments are exposing citizens to an uncontrolled health experiment on a grand scale.

1.  M. Bamberger and R. E. Oswald, "Impacts of Gas Drilling on Human and Animal Health" New Solutions 22: 51-77 (2012).

2.  "A Cluster of Kaposi's Sarcoma and Pneumocystis Carinii Pneumonia among Homosexual Male Residents of Los Angeles and Orange Counties, California." MMWR Morb Mortal Wkly Rep 31: 305-7 (1982).

3.  T. Colborn, et al., "Natural Gas Operations from a Public Health Perspective" International Journal of Human and Ecological Risk Assessment 17:1039-1056 (2011).

4.  L. N. Vandenberg, et al., "Hormones and Endocrine-Disrupting Chemicals: Low-Dose Effects and Nonmonotonic Dose Responses" Endocr Rev. doi:10.1210/er.2011-1050.


Judy Gibson said ..

It seems as though governments all around the world have already been tied up and muzzled by big business. The only way that members of the public can change this is to speak out constantly against such close association of 'business' interests with any agency or institution of government. Our Canadian government is pursuing ever-closer relationships beneficial to no one, but designed to keep it in power. There will inevitably be a backlash, one can only hope that it will come with the next election. The Prime Minister just last week appointed eight new members of cabinet and has given them (and all of cabinet) a list of 'foes' meanwhile proclaiming that these people prevent the government from reaching the citizens with their skewed messages. In fact, as they well know, the very opposite is true. It's difficult to believe the stupidity and cupidity of these politicians, but I suppose the same situation exists in the US and in any country where money commands greater respect than democratic ideals and ethical standards.

July 20, 2013
Yuri Gorby said ..

Sally and others, I am a scientist/professor of environmental microbiology at Rensselaer Polytechnic Institute in Troy, NY, and I share your concerns/frustration with the lack of commitment from the medical community. I am currently engaged in communication with Occupational Medical Professionals to convince them that their knowledge, experience and credibility with industrial health are needed to help residents living in the gas fields. I clearly explain to them that the time to identify the causative agents in the complex emissions coming from these facilities has passed. Too many people, including children, the elderly and pregnant women, are already sick for this to be ignored any longer. Please contact me anytime you wish at

June 20, 2013
Sally Hansen said ..

Please understand I have absolute respect for the medical profession. But why in the world won't the physicians get behind us and help us. Some of us are very ill and the CAUSES of our diseases are not being addressed.

May 11, 2013
Sally Hansen said ..

We continue to hear the same things, same stories, same complaints; ours among them. We will accomplish nothing individually. We need to group ourselves into a National effort. We have chemicals verified in our water, yet we continue to fight for our rights - and we have a surface use agreement w/ the local driller.

May 11, 2013
judith rock said ..

I think that the huge mix of chems at all stages of the activity point to the reuse of extremely toxic mats that would otherwise be very very expensive to dispose of. In addition, the authors point to the fact that the speed of the onslaught across states and regions, coupled with the great number of chems in these mixes make it more difficult, by old school methods, to identify one bad actor chem. If however, we rely on families of bad actor chems and their past track record, it makes the determination more accessible - yes?

June 25, 2012
Knute Rondum said ..

Many, not all, of our legislators are bought and paid for by special interests.

June 23, 2012
Bill Leist said ..

What if fracking results in the pollution of our drinking water from wells? So instead of paying $4.00 a gallon for gasoline we could end up paying $4.00 a gallon for drinking water. Would that be a fair exhange?

June 21, 2012
Phyllis42 said ..

Where did the fracking laws originate. How can there be so much secrecy when it comes to the health of everyone? Why do greedy gas companies have more rights than people, animals, and most importantly our environment to begin with. How many legislatures have received contributions or purchased stock in this industry? Are they involved in insider trading? This is why it is so hard to believe in politics as a noble profession. Follow the money$$$

June 21, 2012
Dorothy REichardt said ..

I find the non-disclosure agreements very disturbing. Obviously, the drilling companies know they have something harmful to hide. I agree that such nondisclosure agreements shoulc be banned. They are against truth and science.

June 20, 2012
Marjorie Wright said ..

People do not realize how damaging and toxic this practice is, when they are sold terms like 'clean natural gas'. On site, the damage is far worse than coal and much more insidious.

June 20, 2012
Amanda Porter said ..

The lives, finances and other resources devoted to this source of energy would be MUCH better used for safe, renewable ones. The documentary, "Gasland," showed the arid wasteland left after fracking, also deformed wildlife giving a hint as to its effect on humans. My poster says, "Sun & wind employ; war & nuclear destroy."

June 20, 2012
Carlene Petty said ..

Personally, if our government actually cared about our health, it would absolutely BAN fracking as a technique for gas extraction.

June 20, 2012

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