According to The Environmental Working Group, a nonprofit
environmental organization, drilling companies are avoiding federal
law and injecting toxic petroleum distillates into wells and threatening drinking water supplies. Opponents of fracing allege that water supplies are threatened because “30 to 60% of the fracing fluid stays in the geological strata and may escape through the existing or new fractures and contaminate surface groundwater.”
What is concerning, opponents claim, is that the additives in fracing
fluids are highly poisonous and carcinogenic. The fluids include, they claim, “potentially toxic substances such as diesel fuel, which contain benzene, ethylbenzene, toluene, xylene, naphthalene and other chemicals; polycyclic aromatic hydrocarbons; methanol; formaldehyde; ethylene glycol; glycol ethers; hydrochloric acid; and sodium hydroxide.” The non-profit agency, ProPublica, reported that in July 2008, a hydrologist sampled a water well in rural Sublette County, Wyoming–the home of one of the largest natural gas fields and has thousands of wells that have undergone hydraulic fracing. The test showed that the water “contained
benzene…in a concentration 1,500 times the level safe for people.”
If you find yourself confused by the propaganda spun by the Petroleum Industry and the claims asserted by the opponents of fracing, I suggest you study the EPA's Proceedings of the Technical Workshops for the Hydraulic Fracturing Study: Fate and Transport @ http://www.epa.gov/hfstudy/epa600r11047.pdf.