Britain's fledgling shale gas industry could be stopped in its tracks after dramatic new evidence established a link for the first time between the "fracking" technology used to dislodge natural gas trapped in rocks and water pollution.
A study by the US Environmental Protection Agency (EPA) into hydraulic fracturing reported finding a host of chemicals in the groundwater around shale gas wells in Wyoming state.
These included petroleum hydrocarbons such as benzene, and tert-butyl alcohol, a fuel additive which is among the more than 500 chemicals that is typically mixed with sand and water and blasted into shale to fracture the rock and release the gas.
The UK's sole operational fracking site, near Blackpool, was suspended in June following complaints from locals about two earthquakes in April and May. The subsequent report into the seismic activity and fracking concluded last month that it is "highly probable" that there was a connection. The report also established that the fracking activity – by Cuadrilla Resources, a company backed by the former BP chief executive Lord Browne of Madingley – was responsible for a further 48 earthquakes.
The Department of Energy and Climate Change is reviewing the report into the Blackpool earthquakes before deciding whether to allow the Cuadrilla site – at Preese Hall in Lancashire – to reopen, and other sites to begin fracking. The DECC is expected to decide whether to allow fracking to proceed in the UK early next year.
Although the report into fracking in the town of Pavillion, Wyoming, was unable to definitively prove the link between the controversial process and water pollution, it concluded "detection of high concentrations of benzene, xylenes ... in groundwater samples from shallow monitoring wells near pits indicates that pits are a source of shallow groundwater contamination in the area of investigation".
Encana, Canada's largest gas company and owner of 123 wells in Pavillion, dismissed the EPA report as "not a definitive conclusion".
For its part, the EPA acknowledged that fracking conditions differ from area to area, with issues such as the depth of activity and proximity to aquifers affecting the chance of possible pollution.