The Hazards of Chemicals Used in Hydrofracking
Tom Shelley

“This stuff is so safe you can drink it”—or so the gas drilling industry would like us to believe. They also compare chemicals used in high-volume, slick-water hydrofracking processes to those found in common household cleaners. Indeed, some small set of those hazardous materials are found in some household products, although many are not. Those that are, often are accompanied by poison control labels.

Top: Chemical transport trucks on a drilling site. Photo: NYS Department of Environmental Conservation. Just above: A 2007 hydraulic fracturing operation on a Marcellus Shale gas well showing the number of trucks involved. Photo: US Geologic Survey

It is estimated by the DEC that 9 to 35 percent, or about 90,000-350,000 gallons per million gallons used, of fracking fluid immediately comes back out of the ground in the form of “flow back” water. Over time, a similar amount of “produced water” is delivered to the surface with the gas produced by the well. This produced water contains some of the fracking chemicals and is further contaminated by heavy metals and radioactivity, along with compounds that are formed by the interaction of the fracking fluids in the hot underground environment with the natural materials in the rock itself. Large amounts of strong salt solutions (brine) are also components of the produced water. These contaminated brines are difficult to dispose of safely.

These fluids are typically stored in ponds near the well pads until they are transported to treatment facilities or off-site storage, such as injection wells. The ponds have leaked and contaminated soil and surface water around the ponds. Volatile organic compounds (VOCs), many of which can cause moderate to severe health problems, evaporate from the ponds before the contaminated water can be removed for processing or off-site storage.

Almost all “flow back” and “produced water” would be classified as hazardous industrial waste if the gas industry were regulated as thoroughly as other chemical-intensive industries. Unfortunately, the industry has a long history of NOT being regulated under federal RCRA (Resource Conservation and Reclamation Act) or state hazardous waste regulations. The health of the communities around natural gas drilling suffers due to of this lack of regulation.

Chemicals and compounds of concern

Here are some of the more commonly used hazardous materials of concern found in the products used in the fracking process:

Benzene and other aromatic hydrocarbons such as toluene, ethylbenzene and xylene (BTEX). These volatile organic compounds (VOCs) are widely found in gasoline, petroleum distillates, diesel fuel and other petroleum-based products that are or have been in the past used in the fracking mixtures.

Polyaromatic hydrocarbons (PAHs) are larger molecules made up of benzene building blocks. All of the above compounds are found in produced water as well as some of the fracking mixtures.

The BTEX suite of hydrocarbons are known carcinogens (leukemia), cause damage to the liver, central nervous system (narcotic effects) and other organs, may cause damage to fetuses, and may cause genetic changes, as well as being irritants of the skin.

Formaldehyde is a gas, used in an aqueous solution. It is used in low concentration, but is very toxic and dangerous even at these low concentrations. It is used as a biocide along with many other very hazardous chemicals. It is a known carcinogen, a severe irritant (eyes, skin, lungs), a systemic poison, and will cause an allergic reaction with repeated exposure.

1,4-Dioxane causes damage to the central nervous system, liver and kidneys. It is toxic, an irritant, and also a probable carcinogen.

Heavy metals—arsenic, barium (dissolved), cadmium, chromium, cobalt, lead, molybdenum, nickel, selenium, silver, strontium, thallium—are found in both the “flow back” water and the “produced water.” Some are components of the fracking chemicals, and others are from the shale itself.

2-Butoxyethanol is readily absorbed by skin or by inhalation. It is an irritant, causes central nervous system effects, may damage the liver, kidneys and lungs, and is a suspected carcinogen. It is also a known endocrine disruptor with effects noted at extremely low concentrations.

There are dozens of other hazardous materials in use in the fracking “chemistry” and the byproducts of the fracking process, all of which can cause serious individual or public health problems if allowed to enter our air or water. We have seen serious instances of such problems in various Western states and close by, very recently, in Pennsylvania.


Tom Shelley is a chemical safety and hazardous materials specialist in Ithaca, New York.

For more information on hydrofracking chemicals and health effects, check out Dr. Theo Coburn’s work with The Endocrine Disruption Exchange at endocrinedisruption.com.