Actually, since 2011 the chemicals are widely disclosed. Most states and the Department of Energy require a list of all chemicals used.
The fracking fluid consists of 90% water, 9.5% sand and 0.5% chemicals. The most used chemicals are salt, co2, sodium carbonate (washing soda, also used as a food additive), citric acid (orange/grapefruit juice), isopropanol (alcohol used in the winter to stop freezing), Glutaraldehyde (used as a disinfectant in drinking water for bacteria elimination), guar gum (extracted from the guar seed, used as a food additive), and methyl alcohol (wood alcohol).
Depending on the type of fracking other chemicals may also be used, but they also must be disclosed to the Department of Energy.