Fracking Chemicals
A long, varying list of chemical additives is added to the water in the fracking process. The toxicity of these additives is variable, and many new chemical compounds are created during the fracking process as some of the added ingredients break-down. Once the fracking water returns to the surface, it needs to be treated before disposal (see Water Disposal below). The amount of chemicals added represents a very small fraction of the total volume of fracking water (around 1%).
However, this very small fraction detracts from the fact that in absolute terms it is rather large volumes that are used. For a well requiring 4 million gallons of water, about 40,000 gallons of additives are pumped in. The greatest risks associated with these chemicals occur during their transportation, as tanker trucks must use the local roads to bring them to the drill pads. An accident involved spilled contents would have significant public safety and environmental consequences.