Arial view of a fracked landscape in Wyoming. Source: Simon Fraser University.

Hydraulic fracturing, commonly referred to as fracking, is a drilling technique that allows the extraction of previously inaccessible natural gas from shale formations. The United States has experienced a fracking boom in the last decade. In February of 2016, the United States was producing 92 billion cubic feet of natural gas per day, much of it from fracking wells.1 The new technology has the potential to allow the United States to become a net energy exporter within a few years.2 Although fracking shows economic potential, new evidence indicates people living near fracking wells may suffer long-term health effects.

Trying to balance the economic benefits of fracking with its health concerns raises important questions about how regulators should deal with the release of pollutants with unknown, but potentially serious, health consequences. Rather than creating an overarching policy, the federal government has left the regulation of fracking up to the states. Pennsylvania, Texas, Oklahoma and North and South Dakota have aggressively pursued the expansion of fracking, while New York has banned the practice due to concerns about the potential long-term impacts of exposure to pollutants that fracking releases into the water and air.

While fracking produces large volumes of natural gas, it also requires huge inputs of fracking fluids. In the span of one week, 11 to 19 million liters of fracking fluid, consisting of water, sand, and chemical additives, are pumped into a well to open and widen cracks in the rock deep underground.3 After being released from beneath the rock, natural gas flows back up the pipe, along with some of the fracking fluid. Flowback fluid—a mixture of naturally occurring compounds and water—also flows to the surface. This fluid is then pumped deep underground for storage, recycled, or taken to a wastewater treatment plant.

Even though chemicals usually only make up two percent of fracking fluid, every well still uses between 150,000–600,000 liters of chemicals.4 Due to a loophole in the Clean Water Act, companies are not required to release any information about the chemicals in their fracking fluids because it is considered proprietary information.5 Therefore, it is impossible to know exactly which chemicals are being used in any given area. Even if the chemicals were known, the health effects of many of the compounds are unknown. One study found that out of the 1,021 identified chemicals used in hydraulic fracturing fluids, only 240 had been tested for toxicity as of 2016.6 In addition to the possible toxicity of the fracking fluid, the flowback fluids also often contain radium and radon, both highly radioactive substances.7

A fracking well in Los Angeles, California. Source: Erik Gustafson.

Fracking and flowback fluids can contaminate surface or groundwater in several ways, such as pipe leakage, chemical spills during well construction, and improper waste water treatment. Around nine percent of fracking wells have pipes that have failed at some point during operations, often due to faulty construction.9 These failures occur three to six times more often than those of conventional natural gas wells, and often lead to the contamination of nearby drinking wells.9 Another form of contamination occurs in the early stages of development, when each fracking well requires over a thousand truck trips to transport materials.10 These trucks often transport hazardous chemicals, which are then at heightened risk of spilling into streams and rivers. Flowback fluid can contaminate water sources when it is improperly treated in wastewater treatment plants and recycled into drinking water.9

The contamination of water during the fracking process may affect the health of nearby communities. Residents near wells have complained of skin rashes, nausea, abdominal pain, respiratory difficulties, headaches, dizziness, eye irritation, throat irritation, nosebleeds, anxiety, and stress that demand further investigation.7 These short-term health effects, reported anecdotally by doctors in fracking boom areas, require further investigation to determine how their causes are related to fracking and how widespread they are.

Many of the chemicals used in fracking are suspected to harm reproductive health. One study found that of those chemicals whose toxicity is known, 43% have negative effects on reproductive health.1 Some studies have demonstrated that populations living closer to a fracking well are at higher risk of pre-term births and birth defects.1 There is also a possible connection between fracking and increased incidence of miscarriage and low birth weight, but this relationship is less clear.1 These chemicals do not just affect women’s reproductive health; studies suggest that they may also reduce sperm viability, count and motility.1

Chemicals used in fracking can impact reproductive health through various, often unclear, mechanisms. Some of the chemicals are known to be estrogenic, which means they mimic the structure of estrogen, a natural hormone that is particularly important for regulating the female body. Others may affect receptors for estrogen and other hormones. Both of these effects can lead to infertility or cancer by disrupting the regulation of estrogen that is necessary to control the female reproductive system. Other chemicals are suspected to damage DNA in the egg and sperm, which can increase the risk of birth defects.1

Although the media most commonly publicizes concerns about water safety, fracking also results in air pollution. One study estimated that in Pennsylvania, air pollutant emissions associated with shale gas extraction resulted in $7.2 to $32 million in region-wide environmental and health damages in 2011 alone.10 Fracking wells often release trapped methane, benzene, carbon monoxide, hydrogen sulfide, nitrogen oxides, particulate matter, sulfur dioxide, and volatile organic compounds (VOCs) from beneath the shale rock, in addition to natural gas, all of which are known respiratory irritants. Benzene is also a human carcinogen. Polyaromatic hydrocarbons (PAH) and benzene, which are both respiratory irritants and carcinogenic, have been found at illegal levels even at distances over a mile away from fracking wells.10 There are also high levels of ground-level ozone, another respiratory irritant that can increase the frequency of asthma attacks, around wells.11 Studies have shown that people who live near wells are at increased risk of asthma attacks, most likely due to fracking-related air pollution.3

Workers at fracking wells are at particularly high risk of poor health due to increased exposure to toxic chemicals. In particular, occupational exposure to respirable crystalline silica is associated with numerous health effects, including silicosis, lung cancer, tuberculosis, autoimmune diseases, and kidney disease.9 The long-term health effects of fracking on workers are still unclear, however, because it has only been a widely-used practice for ten years. 5 With hundreds of thousands of fracking workers in the US, though, any occupational health hazards that may occur are likely to be expensive to treat.12

The long-term effects of fracking on general populations are also unclear, but are likely to include increased cancer rates. Many of the chemicals that have been detected in the drinking wells and air surrounding fracking wells are known carcinogens, but because cancer can take years to develop, their effect on cancer rates in these regions is still unknown. In addition, not all of the chemicals that are commonly used have been tested for carcinogenic effects. Even if all of these untested chemicals were harmless in isolation, multiple chemicals can interact in unknown ways in the body, sometimes amplifying the carcinogenic effect.8 When chemicals are tested for toxicity, they are tested individually and so their interactions with other chemicals are not investigated. This systematic flaw in scientific toxicity testing causes problems for determining the exact effects of drinking water that is polluted with multiple fracking fluid chemicals.

Chemical interaction is only one field of study where there is an acute need for more research into the health effects of fracking. The potential reproductive health impacts described earlier are not proven because most studies have been relatively small-scale. These studies are suggestive of health hazards, but are not conclusive.7 Conducting studies that prove causation, and not just correlation, is expensive and often time-consuming. In order to protect the health of residents in fracking areas, however, it is necessary to know exactly what risks they face.

In addition to physical health, the development of the fracking industry can impact the mental and social health of communities. Most of the new extraction areas are in very rural parts of Pennsylvania, the Dakotas and Texas. The influx of workers creates shale gas boomtowns and increases industrial pollution within the area. Many residents express concerns about sleep disruption from increased traffic, and increasing levels of drug use and sexual assault.9 These issues, combined with a feeling of being powerless to stop the changes, can lead to increased chronic stress. 10

Although fracked natural gas is often touted as a cleaner and more environmentally friendly alternative to coal and oil because it produces less carbon dioxide when burned, most measurements do not account for methane leakages that occur and the number of truck trips that are required for fracking wells. 13 Fracking releases twice as much methane, a potent greenhouse gas, from leaks as conventional drilling does.4 When total greenhouse gas emissions are considered, fracking may not be more environmentally-friendly.13 The high carbon emissions from the extraction and combustion of fracked natural gas are contributing to anthropogenic climate change, which is projected to have serious health impacts, including the spread of mosquito-borne diseases, increased malnutrition, increased rates of asthma, and increased mortality due to higher incidence of heat waves, droughts, floods, wildfires, and other natural disasters.14 When considering the health impacts of fracking, it is important to bear in mind the future impacts of the combustion of fossil fuels, which will affect communities around the world.

Fracking presents a quandary for lawmakers. Should an industry with unclear, but potentially serious, detrimental effects on health be allowed to proceed? Should a ban only be implemented once there is conclusive evidence of harm? Within the United States, individual states have answered these questions differently. For example: although New York and Pennsylvania both lie on top of the Marcellus shale formation, their governments have regulated fracking in completely opposite ways.

Map of US shale fracking regions. Source: Elias Schewel.

In 2008, New York implemented a temporary moratorium on fracking while the health and environmental departments investigated its impacts. After seven years of study, the decision was made to extend the ban. The Department of Environment Commissioner cited “significant adverse impacts to land, air, water, natural resources and potential significant public health impacts that cannot be adequately mitigated” as the reason for the decision.15 New York’s ban is in line with the precautionary principle of environmental justice, which states that if a substance is suspected to be hazardous to human health or the environment, it should be banned until proven safe.16

In contrast, neighboring Pennsylvania has aggressively pursued fracking. There are currently 7,788 fracking wells in the state and the number is projected to continue to increase.17 This industry expansion has had significant impacts on the southwestern and northeastern parts of the state, formerly rural areas that are, in effect, experiencing accelerated industrialization. Fracking employs 33,000 people in the state and financially benefits those who own mineral rights and lease their land to fracking companies.17 Residents, however—particularly those in Appalachia, which has a long history of extractive industries leaving residents poor—are wary. Pennsylvania’s environmental policy is based on the principle that chemicals may be used in the environment until scientists have biomedical proof that they cause harm to human health. This means, however, that they are gambling with health; if fracking has as severe a health effect as some studies suggest, it may dramatically increase rates of cancer, asthma and reproductive disorders before being proven to cause conclusive harm. These diseases are expensive to treat and could offset some of the purported economic benefits of fracking.

Residents in fracking areas have raised concerns about environmental justice. A fundamental principle of environmental justice states that there should be an equal distribution of environmental harms across the entire population.19 In states, such as Pennsylvania, Texas, Oklahoma and the Dakotas, where fracking has been allowed at the state level, the decision-making power about whether fracking companies come into a particular community lies with those who own mineral rights. Since not all residents own the mineral rights to their land, this means that some of those who are most affected by the pollution have no power to stop fracking taking place in their community. Additionally, only those who own mineral rights experience direct economic benefit, in the form of royalties paid by fracking companies. Everyone living near a fracking well is recommended to test their drinking wells for hazardous pollutants every six months, but in rural areas, where many people rely on wells for water, testing can be prohibitively expensive.10 Therefore, residents who do not own mineral rights may disproportionately suffer negative economic and health effects from fracking.

Fracking workers entering an oil and gas pad in Oklahoma. Source: Joshua B. Pribanic.

The city of Denton, Texas is an illustrative case study. Denton is an urban area that sits on top of the Barnett Shale region and was one of the first cities where fracking was tested. Homeowners living in close proximity to drill pads have filed numerous complaints about noise and light pollution, and report increased nosebleeds, nausea, headaches and other symptoms. The majority of those who benefit directly from fracking, however, do not experience these negative effects because 61.4% of the mineral rights owners in Denton are not residents of the city.19 This means they receive direct compensation for fracking but, since they do not live in close proximity to the wells, do not experience the health risks. Because the number of mineral rights owners living in homes close to fracking wells is much smaller than the number of those without mineral rights, the majority of those at risk of potentially severe health effects in Denton both exercise no power over the decision to let fracking companies build wells and receive no direct financial compensation for the risk to their health.

Fracking presents an unclear, but likely significant, threat to human health. Its effects are beginning to be studied more in-depth, but many people living in fracking boom areas are currently acting as human experiments. The long-term effects of living with fracking-contaminated drinking water and air pollution may not be known for several decades and all current studies are complicated by the shocking fact that companies are not required to release information about the mixture of chemicals that they use. Those who most benefit from fracking usually do not live in the vicinity of a well, and are therefore not at risk from the many possible health effects. Legislators have an obligation to look closely at these risks before allowing fracking to proceed unquestioned. They are responsible for the wellbeing of the communities affected by fracking. Legislators play a particularly key role because those most vulnerable to the effects of fracking are often powerless to regulate it. In addition, lawmakers need to consider the effects that climate change, caused by the combustion of the fossil fuels extracted through fracking, will have on the health of communities around the world.

Emma Phelps is a sophomore from the United Kingdom and is majoring in Ecology and Evolutionary Biology. She can be contacted at



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