As humans become more reliant on the modern electrical and mechanical devices that make life easier and more productive than ever before, newer methods of extracting the fuels that power these conveniences are constantly being developed and perfected. One method of fuel extraction — hydraulic fracturing (“fracking”) — seems to be highly controversial for the threat it poses to the physical environment as well as possible health consequences to humans and animals who live near a fracking operation.

A nationwide collaboration of research scientists has recently published the findings of the largest ever study of fracking’s effect on humans, along with the conclusion that oil and gas fracking is likely to endanger human reproduction and healthy development of infants and children. Researcher Susan C. Nagel of the University of Missouri led the study that involved examination of more than 150 peer-reviewed studies of the effects of the chemicals used in or produced by unconventional oil and gas (UOG) operations; fracking is one form of UOG operation.

The Nagel study is considered a weight-of-evidence review because it draws conclusions from many studies conducted for various reasons and using varying methodologies rather than from a single study designed to pinpoint cause and effect. Nagel says, “There are far fewer human studies than animal studies; however, taken together, the studies did show that humans can be harmed by these chemicals released from fracking.”

Collectively, the studies indicate laboratory animals exposed to fracking chemicals and livestock animals living near fracking zones suffer reproductive and developmental damage from the chemicals. Human studies reveal the same finding. These chemicals are known to cause:

  • Birth defects
  • Impaired fetal growth
  • Infertility
  • Low birth weight
  • Miscarriage
  • Preterm birth
  • Reduced semen quality

The two main avenues of exposure to these toxic chemicals near a fracking area are air and water.


Chemicals such as benzene, formaldehyde, and hydrogen sulfide contaminate the air, sometimes in quantities that significantly exceed the Minimal Risk Level of Hazardous Substances established by the Agency for Toxic Substances and Disease Registry. These chemicals affect the body’s gastrointestinal, respiratory, neurological, and immune systems as well as the liver and kidneys.


Almost everyone has seen video clips of tap water catching on fire due to contamination by flammable chemicals associated with fracking. Eating and drinking water contaminated with these chemicals causes harm but bathing in and cleaning anything with this water is dangerous, too. Every time this contaminated water is run in a household or other enclosed building, evaporation transmits these chemicals from the water into the air. Waterborne chemicals present a contact threat as well as an inhalation threat.

More than 750 chemicals are known to be associated with the fracking process, including lead-210, radium, thorium, and uranium, all of which are radioactive. The radioactive nature of these chemicals within rock formations and sand fields helps identify these areas as promising sites for oil and gas deposits.

According to the Nagel study, more than 15 million Americans live within one mile of a UOG operation (also known as a “play”). Almost all the lower 48 United States have a fracking play or basin within their borders.


  1. Nagel, Susan C., et al. “Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operators.” De Gruyter / Reviews on Environmental Health, Volume 29, Issue 4 (Dec 2014). Walter de Gruyter GmbH. Dec. 2014. Web. 30 Dec. 2014.
  2. Energy Information Administration. “Lower 48 states shale plays (map .pdf).” EIA. Energy Information Administration. 9 May 2011. Web. 30 Dec. 2014.