The risks to people's health from fracking are low as long as the process is "properly run and regulated", health officials have said.
A report published today by Public Health England (PHE) – an agency of the Department of Health – says the risks from air pollutants, radon and contamination of ground water and drinking water were low provided safeguards were in place.
The report said it was "unlikely" that groundwater would become contaminated by fracking for shale gas because of the depth at which it occurs.
But the experts said controls were needed over how chemically contaminated water, which is an essential requirement for fracking, is stored and disposed of as evidence suggests poor storage of this "flowback" water could lead to accidents and the release of methane and other chemicals into water.
Professor Quentin Fisher, Professor of Petroleum Geoengineering at the University of Leeds, said: “This is yet another study suggesting that contamination of the groundwater due to the hydraulic fracture process itself is unlikely.
“The two main risks identified are surface spills and leakage along boreholes. These risks can be dramatically reduced by the development of a robust regulatory framework.
“I think it’s particularly important for the public to understand that leakage along boreholes is far less likely in the UK compared to the USA because we have never had a large onshore petroleum development program so pre-existing boreholes close to the shale gas resources are not a significant issue.
“Overall, the report provides even more evidence that production of gas from shale can be made very safe.”
The report – described as an "initial review" – is based on research mostly from the USA, which officials admitted could not easily be translated to the UK where no studies have taken place, but said the evidence suggests overall risks are minimal.
Fracking – also known as hydraulic fracturing – is also expected to be safer in the UK than the US, they said.
Professor Stuart Haszeldine, Professor of Sedimentary Geology, University of Edinburgh, said: “The PHE report on contamination is well balanced, and rightly points out that drilling and production of fluids from underground can also produce a range of natural pollutants in dilute form.
“The substances listed are no different to those already handled during North Sea oil and gas exploitation, so the technology exists to cope. Challenges for Government are to ensure high quality analysis of groundwater before shale gas drilling commences – that may require specialist shallow sampling boreholes.
“Also to ensure that the UK has enough inspectors to ensure that strong rules are adhered to. The University of Edinburgh is already developing robust baseline monitoring to detect any shale gas contamination in groundwaters.”
Evidence from the US contained in the report shows emissions from fracking are a "significant source" of many air pollutants and fracking sites also contribute to higher levels of ozone.
A review from the European Commission concluded that the "potential risks to human health and the environment from releases to the air across all phases of development was high".
But the report said the US has now put in place new regulations to cut these emissions and argued similar controls must be introduced into the UK.
One US study in today's report suggests a higher risk of cancer for people living near fracking sites, but PHE experts said it was a poor quality study and the report also concluded it was "unlikely" that fracking would lead to a significant increase in people's exposure to the naturally occurring radioactive gas radon.
In conclusion, the report said problems encountered in the US "appear to have been due to operational failures and inadequacies in the regulatory environment".
Dr John Harrison, director of PHE's centre for radiation, chemical and environmental hazards, said: "The currently available evidence indicates that the potential risks to public health from exposure to emissions associated with the shale gas extraction process are low if operations are properly run and regulated.
"Where potential risks have been identified in other countries, the reported problems are typically due to operational failure.
"Good on-site management and appropriate regulation of all aspects of exploratory drilling, gas capture as well as the use and storage of fracking fluid is essential to minimise the risks to the environment and health.
"PHE will work with regulators to ensure appropriate assessment of risk from all aspects of shale gas extraction."
Professor John Newton, chief knowledge officer at PHE, said: "The report makes a number of recommendations, including the need for environmental monitoring to provide a baseline ahead of shale gas extraction, so that any risks from the operation can be appropriately assessed.
"Effective environmental monitoring in the vicinity of the extraction sites is also required during the development, production and post-production of shale gas wells.
"In due course it will also be important to assess the broader public health impacts such as increased traffic, the impact of new infrastructure on the community and the effect of workers moving to fracking areas."
The review looked only at the immediate health impacts of fracking and not other issues, such as climate change and greenhouse gas emissions, water resources, or how noise, odours and fracking sites would affect local people.
Prof Newton said a lot was already known about the health effects of some of the products of fracking – such as methane – in other industrial settings.
He said of today's report: "On the whole, the results are reassuring. We do not expect any adverse health effects."