The risk posed by fracking remains significant, a leading environmental health expert in Northern Ireland has said.
There are still too many unknowns and gaps in the evidence surrounding the emerging use of shale gas, said the director of the Institute of Environmental Health in Northern Ireland.
The Australian energy exploration company Tamboran hopes to begin extracting gas in Fermanagh by early next year.
The director of the environmental health institute, Gary McFarlane, said: "The precautionary principle must still hold - there are still too many unknowns and in the evidence vacuum that still exists my own view is that wider risks must be considered significant until they have been objectively proved otherwise."
The controversial method of extracting gas from shale rock has historically used a solution containing potentially toxic chemicals to break up rock and release the gas.
The process has consistently come under fire from a broad spectrum of environmental experts and campaigners, including a coalition of the world's biggest institutional investors which stepped up pressure on oil and gas companies to become greener.
Tamboran has pledged no chemicals will be used in its fracking process.
Although gas is the "cleanest" of the fossil fuels, there is a lack of scientific literature around the intensive method, according to a recent Canadian public health report. Its impact on community or mental health and socio-economic wellbeing has been questioned.
The Canadian report also highlighted a lack of public health input into the investigation of fracking thus far and said there were still too many unknown risks.
Mr McFarlane warned it was unclear how much gas could be recovered from the UK's deposits and said extraction could affect CO2 emissions figures because it releases methane.