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TEDX 

The Endocrine Disruption Exchange 

P.O. Box 1407, Paonia, CO 81428 

970-527-4082 

www.endocrinedisruption.org 

tedx@tds.net

INTRODUCTION 

The following summary is based on an analysis of the potential health effects of products and chemicals used 

during natural gas operations. The names and possible health effects of the products and chemicals summarized 

below are available in an Excel spreadsheet for easy sorting and searching.* Note that this is not a complete list 

of products and chemicals used in natural gas operations. 

METHODS: What we did 

Data sources 

Acquiring information about the products and chemicals used in natural gas operations continues to be 

extremely difficult. TEDX has spent several years collecting data from a variety of sources including state 

Emergency Planning and Community Right-to-Know Act (EPCRA) Tier II reports, Environmental Impact 

Statement and Environmental Assessment Statement disclosures, rule-making documents, accident and spill 

reports, the U.S. Bureau of Land Management, the U.S. Forest Service, state agencies, non-profit organizations, 

and the natural gas industry. 

For nearly every product identified, Material Safety Data Sheets (MSDSs) were acquired, with the exception of 

a few that came from state Tier II Reports. MSDSs are designed to inform those who handle, ship, and use 

products that contain toxic chemicals about their physical and chemical characteristics, and their direct and/or 

immediate health effects, in order to prevent injury while working with the products. The sheets are also 

designed to inform emergency response crews in case of accidents or spills. Many MSDSs do not address the 

outcome of long term, intermittent or chronic exposures, or adverse health effects that may not be expressed 

until years after the exposure. The Occupational Safety and Health Administration (OSHA) requires product 

manufacturers to include certain elements in MSDSs, but they are not required to submit them to OSHA for 

approval before attaching them to their products. Thus, accuracy and completeness are entirely up to the 

company that produces the MSDS. 

MSDSs can be lacking in information in many ways. The majority of MSDSs do not disclose 100% of the 

product composition. They also list non-specific ingredients, such as “surfactant” or “biocide” that describe the 

function of the ingredient but do not specify the ingredient name. Other vague words that are used include: 

proprietary, mixture, unspecified, various, unregulated, or no hazardous ingredients. The most specific way to 

identify chemical ingredients is by using CAS numbers. The American Chemical Society developed the CAS 

(Chemical Abstract Service) number system using unique number sequences to identify chemical elements, 

compounds, isomers of chemicals, polymers, biological sequences, or mixtures. CAS numbers provide a 

universal identity to substances that can be known by different names. 

Health Effects 

Only chemicals with CAS numbers could be accurately investigated for their health effects. Information about 

the potential health effects of each chemical with a CAS number was obtained from these sources: 

• Material Safety Data Sheets 

• Publicly available government databases: 

o TOXNET 

o Hazardous Substances Database 

• Published scientific studies (located through PubMed and Web of Science) 
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Information was often limited because of the lack of published research on many products, including industry 

laboratory studies submitted to EPA for registration but classified as confidential business information. 

Health effect data were organized into 14 health categories, focusing on the main organs and systems that are 

identified on MSDSs, government toxicological reports, and in the medical literature. The categories encompass 

all seven priority health conditions identified by the Agency for Toxic Substances and Disease Registry. For our 

summary analysis we subsumed developmental and reproductive health effects under the category for endocrine 

disruption, resulting in 12 categories. The 12 health effect categories are: skin, eye and sensory organ; 

respiratory; gastrointestinal and liver; brain and nervous system; immune; kidney; cardiovascular and blood; 

cancer; mutagenic; endocrine disruption; other; and ecological effects. 

Data Analysis 

The products, the chemicals they contain, and their health effects were entered into an Excel spreadsheet. We 

also entered data indicating what percentage of each product was disclosed in the MSDS. Then, using only the 

chemicals that had a CAS number, we produced a profile based on how many chemicals showed evidence of 

potential health effects in each of the 12 categories. We also created separate profiles for the water soluble 

chemicals and volatile chemicals. 

RESULTS: What we learned

Product composition disclosure 

Products may contain more than one chemical, and a given chemical may occur in more than one product. Our 

spreadsheet currently contains 980 products. For 421 of the 980 products (43%), less than 1% of the total 

composition of the product was reported on the MSDS (Figure 1). Less than 50% of the composition was 

reported for 136 products (14%), and between 51% and 95% of the composition was reported for 291 (30%) of 

the products. Only 133 products (14%) had information on more than 95% of their full composition. 

For each product, we totaled the number of health effects of the chemicals in that product. Figure 2 shows that 

10% of the products had no health effects, while 90% had at least one potential health effect. Nearly half of the 

products (47%) contained one or more chemicals considered to be endocrine disruptors, which are chemicals 

that interfere with the endocrine system, including development and reproduction. 
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Chemical summary 

In the 980 products identified above, there were a total of 649 chemicals. Specific chemical names and CAS 

numbers could not be determined for 286 (44%) of the chemicals, therefore, the health effects summary is based 

on the remaining 362 chemicals with CAS numbers. Figure 3 shows percentages of the 362 chemicals that were 

found to be associated with effects in each of the 12 health effect categories. Note that many chemicals have 

health effects in more than one category. Over 78% of the chemicals are associated with skin, eye or sensory 

organ effects, respiratory effects and gastrointestinal or liver effects. The brain and nervous system can be 

harmed by 55% of the chemicals. These four health effect categories (on the left side of the figure) are likely to 

appear immediately or soon after exposure. They include symptoms such as burning eyes, rashes, coughs, sore 

throats, asthma-like effects, nausea, vomiting, headaches, dizziness, tremors, and convulsions. Other effects, 

including cancer, organ damage, and harm to the endocrine system, may not appear for months or years later. 

Between 22% and 47% of the chemicals were associated with these possibly longer-term health effects. Fortyeight percent of the chemicals have health effects in the category labeled ‘Other’. The ‘Other’ category includes 

such effects as changes in weight, or effects on teeth or bones, for example, but the most often cited effect in 

this category is the ability of the chemical to cause death. 
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Figure 4 breaks out the health effects by pathway of exposure. A total of 210 chemicals (58%) are water soluble 

while 131 chemicals (36%) are volatile; in other words, they can become airborne. Of these volatile chemicals 

over 93% can harm the eyes, skin, sensory organs, respiratory tract, gastrointestinal tract or liver. Compared 

with the soluble chemicals, far more of these chemicals (86%) can cause harm to the brain and nervous system. 

Seventy-two percent of the volatile chemicals can harm the cardiovascular system and blood, and 66% can 

harm the kidneys. Overall, the volatile chemicals produce a different profile with higher percentages than the 

water soluble chemicals. Because they can be inhaled, swallowed, and also reach the skin, the potential for 

exposure to volatile chemicals is greater. 

Appendix A provides a list of the chemicals with CAS numbers found in the highest number of products and 

their associated number of health effects, to assist in prioritizing the chemicals to be monitored. 

DISCUSSION: What we have to say about it 

Clearly, many of the products and chemicals used by the natural gas industry are not benign. As the industry 

continues to expand and tap into additional natural gas formations, the list of products will grow. New products 

and chemicals continue to be introduced into the market as a result of increasing competition among those who 

manufacture and sell products; and product specialization to address the geology and varying geochemical 

conditions of natural gas formations. 

Without full knowledge of what products and chemicals are being used, it is extremely difficult to know what 

air and water quality tests to conduct. Appendix A displays the chemicals that appear in the highest number of 

products, along with the number of health effects of each chemical. Although this does not necessarily equate to 

the most frequently used chemicals at any given time or location, it can provide some guidance in developing 

air and water quality monitoring protocols. Regular air and water quality monitoring in and around natural gas 

development should become standard procedure that includes baseline monitoring prior to new wells being 

developed. For those living near natural gas development, measurable changes in air quality will take place well 

before changes in drinking water quality. In addition to the chemicals introduced during drilling and fracturing, 

air quality monitoring should target the numerous volatile, naturally occurring, toxic chemicals found 

underground that may also be released during the process. 

Of note is that 47% of the products have the potential to affect the endocrine system, including human and 

wildlife development and reproduction. The endocrine system is the exquisitely balanced system of glands and 

hormones that regulates such vital functions as body growth, response to stress, sexual development and 
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behavior, production and use of insulin, rate of metabolism, intelligence and behavior, and the ability to 

reproduce. The endocrine system operates at very low concentrations of hormones, often in parts-per-billion or 

less, making it susceptible to very low levels of exposure, which can impact organisms and their offspring, 

including humans. Prenatal exposure should especially be avoided. Endocrine disrupting effects include reduced 

sperm production, infertility, hormone imbalances, effects on the thyroid, adrenals, pituitary, and more. Effects 

like these might not be seen for months or years and would be difficult to trace back to exposure to gas industry 

chemicals. 

For over seven years, environmental and public health advocates have called for full product disclosure of 

drilling and fracking chemicals. After a nurse became critically ill while attending a laborer involved in a 

fracking accident, and the attending physicians could not find out what she was exposed to, the real urgency for 

full disclosure became apparent. In 2008 Colorado passed a rule (the first of its kind) that upon request through 

the Colorado Oil and Gas Conservation Commission, operators must disclose product ingredients to victims or 

their physicians in case of an accident. Unfortunately, the response to such a request could take several days, 

long after it could be of any assistance for emergency diagnosis and treatment. In 2010, Wyoming became the 

first state to require publicly available disclosure of chemicals in fracking products, including the volumes or 

quantity of chemicals used. Already Wyoming is receiving requests for proprietary status which would prevent 

public disclosure of a number of fracking products. 

These efforts are a good start, but there is much more information that needs to be disclosed fully and publicly. 

Each drilling and fracturing event is custom-designed depending on the geology, depth and resources available. 

The chemicals and products used and the amounts or volumes used can differ from well to well. Complete 

records for each well must be kept for an accurate accounting of what is being introduced into watersheds, air, 

and soil. This information should include the exact location of the well; the complete composition of the fluids 

injected underground, including the complete formulation, weight and volume of every product and chemical 

used; the depths and pressures at which material/mixtures were injected; the amount and composition of the 

recovered liquids; and their disposal method and location. 

However, while the drilling and fracking contractors can be required to tell everything they know about a 

product, they largely rely on MSDSs from the product manufacturers. As our analysis indicates, many MSDSs 

provide information on only a fraction of the full product ingredients. There will not be true full disclosure until 

the product manufacturers divulge 100% of the chemical ingredients in their products. It is time for those 

charged with protecting public health and the environment to demand full disclosure directly from the natural 

gas products industry. Additionally, responsible drilling and fracking companies should be insisting on safer 

products from their suppliers to protect the health of their employees and reduce their liability. Most 

importantly, the industry needs to assure its drilling and fracking fluids and toxic byproducts are retained in 

closed-loop production systems that prevent the release of any toxic chemicals into the ambient environment. 

For a more in-depth discussion of these issues, read our manuscript “Natural Gas Operations from a Public 

Health Perspective” accepted for publication in the International Journal of Human and Ecological Risk 

Assessment. 

*To download the database of products, chemicals and health effects in an Excel spreadsheet; a PDF of this 

Summary Statement; and our manuscript “Natural Gas Operations from a Public Health Perspective” go to 

http://www.endocrinedisruption.com/chemicals.multistate.php. 
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Appendix A. Chemicals found in the highest number of products 

Chemical CAS # 

Number 

of 

Products 

Number of 

Health 

effects 

Crystalline silica, quartz 14808-60-7 124 7 

Methanol 67-56-1 76 11 

Isopropanol (Propan-2-OL) 67-63-0 50 10 

Petroleum distillate hydrotreated light 64742-47-8 24 6 

(2-BE) Ethylene glycol monobutyl ether 111-76-2 23 11 

Bentonite 1302-78-9 20 6 

Diesel 2 68476-34-6 20 10 

Naphthalene 91-20-3 19 12 

Ethylene glycol 107-21-1 18 10 

Aluminum oxide 1344-28-1 17 3 

Sodium hydroxide 1310-73-2 17 5 

Barite (BaSO4) 7727-43-7 15 5 

Heavy aromatic petroleum naphtha (aromatic solvent) 64742-94-5 15 5 

Sodium chloride 7647-14-5 15 9 

Crystalline silica, cristobalite 14464-46-1 14 5 

Mica 12001-26-2 14 3 

Crystalline silica, tridymite 15468-32-3 13 3 

Hydrochloric acid (HCl) 7647-01-0 13 7 

Xylene 1330-20-7 12 10 

Glutaraldehyde 111-30-8 11 11 

Guar gum 9000-30-0 10 3 

Iron oxide (Fe203, Diiron trioxide) 1309-37-1 10 4 

Potassium chloride 7447-40-7 10 8 

Potassium hydroxide 1310-58-3 10 7 

Xanthan gum 11138-66-2 10 4 

Fuel oil #2 68476-30-2 9 11 

Hydrotreated heavy petroleum naphtha 64742-48-9 9 8 

Limestone (Calcium carbonate) 1317-65-3 9 3 

Sodium carboxymethylcellulose (Polyanionic cellulose) 9004-32-4 9 5 

Butanol (N-butyl alcohol, Butan-1-OL, 1-Butanol) 71-36-3 8 8 

Calcium hydroxide 1305-62-0 8 8 

Crystalline silica (silicon dioxide) 7631-86-9 8 4 

Ethanol (Acetylenic alcohol) 64-17-5 8 12 

Formic acid 64-18-6 8 11 

Graphite 7782-42-5 8 4 

2-Ethylhexanol 104-76-7 7 11 

Acetic acid 64-19-7 7 9 

Ammonium bisulfate 10192-30-0 7 6 

Asphaltite (Gilsonite, Hydrocarbon black solid) 12002-43-6 7 4 

 Calcium chloride 10043-52-4 7 8 

Ethylbenzene 100-41-4 7 11 

Ethoxylated nonylphenol 9016-45-9 7 6 

Petroleum distillate naphtha 8002-05-9 7 12 

Polyacrylamide/polyacrylate copolymer (Copolyer of acrylamide 

& sodium acrylate, partially hydrolyzed polyacrylalmide) 25085-02-3 7 3 

Propargyl alcohol (Prop-2-YN-1-OL) 107-19-7 7 9 

Tetramethylammonium chloride 75-57-0 7 8