Hydraulic fracturing (also called hydrofracking or fracking) is a process in which millions of gallons of water, sand and chemicals are pumped underground to break apart rock in order to release oil and natural gas.

The US EPA Toxics Release Inventory (TRI) program requires facilities in certain industries that manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. Hydraulic fracturing is currently not a TRI-covered industry and so is not represented in TOXMAP.

EPA scientists are conducting a study of hydraulic fracturing to better understand any potential impacts on drinking water and groundwater. Congress has released a report on hydraulic fracturing (PDF, 156 KB) [Download Acrobat Reader] that lists 29 toxic chemicals used in fracturing (see Table 3 of this report). Click on the links in the table below for additional information on these chemicals: