Working closely with colleagues at the London School of Hygiene and Tropical Medicine, Professor Depledge has recently published a review of our current understanding of the health impacts of fracking.
Here he provides us with an overview of what we know – and what we don’t.
Fracking is never far from the headlines at the moment, with David Cameron recently urging local councils to “get on board” and back the industry, in return for more money in tax revenue.
Yet with contradictory rhetoric and a large number of ‘unknowns’ surrounding the extraction of gas by induced hydraulic fracturing of gas-bearing rock – or ‘fracking’ – what do we actually know about the potential health effects of the process?
Fortunately, fracking is at a very early stage in the UK, with only one shale gas well so far tested. This provides an important opportunity for scientists to gather information and study the health and environmental effects – before any large-scale developments take place.
Despite the industry gaining momentum across the world, scientific study of the health effects of fracking is in its infancy. Yet early findings suggest that this form of extraction might increase health risks compared with conventional oil and gas wells, with larger surface footprints of fracking sites, their close proximity to locations where people live, and the need to transport and store large volumes of toxic materials likely to pose negative consequences for health.
In the USA, where more than 52,000 shale gas wells have been drilled, research suggests that risks of environmental contamination are present at all stages of extraction. These include surface spills and leakages, emissions from gas-processing equipment, and pollution from the large numbers of heavy transport vehicles involved. There is therefore ample opportunity for pollutants to contaminate the air, and ground and surface water.
What about those working on the wells? Whilst the toxicological data for the chemicals injected into wells (so-called ‘frac fluid’) indicate that many of them have known adverse effects on health, there are some for which no toxicological data exists.
Assessment of potential risks has been difficult in the USA because drilling operators are not required to disclose which chemicals are used. Thankfully, the UK Government has accepted the recommendation from the Royal Society and Royal Academy of Engineering Working Group on shale gas extraction for full disclosure.
Detailed studies are needed along the entire supply chain of shale gas in order to understand potential health issues. The socioeconomic implications of shale gas development on local communities before, during, and after extraction, and how risks should be communicated, are especially important research priorities.
In addition to local health and environment threats, a key consideration is the contribution of shale gas extraction to greenhouse gas emissions and, thus, to climate change.
Although there is conflicting evidence about the comparative contribution of greenhouse gases from shale gas relative to coal, evidence from the USA indicates that instead of replacing coal, shale gas has rapidly become an additional source of fossil fuel, leading to an increase in overall global greenhouse gas emissions. This view has recently been lent support in BP’s Energy Outlook 2035 report.
The degree to which shale gas extraction is developed should be based on comparisons with other energy options, including renewable energy sources, and greater investment in energy efficiency measures, taking full account of environmental, economic, and health implications.
When considering the long term viability of fracking, it will be important for health impact assessments to include the long-term implications of waste disposal, fugitive methane emissions, and other legacies with implications for human health, as opposed to analyses of only environmental and public health risks during active development.
With a technically challenging and globally industry, it is vitally important that data and expertise is readily shared.
Climate policies and declining fuel reserves will probably drive substantial changes in energy policy in the coming decades. Shale gas development shares many science policy questions with other proposed energy alternatives and, therefore, provides a good case study into the different factors at play – and the associated challenges.
With pressure increasing from industry and politicians alike, the local, national and global costs and benefits of new energy options over the short, medium and long term need to be assessed, and quickly.
Read more in a review published by Professor Depledge and colleagues in the Lancet.