Shale gas cancer claims – not all they’re fracked up to be
It’s often claimed that shale gas extraction by hydraulic fracturing or fracking is linked to increases in cancer rates, with some people going as far as to suggest there is a proven link. For local communities facing the prospect of shale gas exploration, this must seem like a frightening prospect. We’re not oncologists or epidemiologists, but we don’t believe the evidence supports the cancer claims for three key reasons.
Firstly, correlation doesn’t equal causation.
In the scientific community, it’s well known that correlation does not necessarily equal causation. For instance, some people claim there is a link between certain cancers and mobile phones – but cancer doesn’t cause mobile phones.
Many of the health studies citing cancer links are from the US. Whilst appearing to have identified health anomalies, these studies have been unable to categorically then establish a causal link to nearby shale gas extraction activities.
Similarly, it’s important to recognise that hazard and risk, though often conflated by people without adequate knowledge, are entirely separate concepts.
Of course, there are some activities and chemicals used in shale gas extraction that are hazardous, but the likelihood of those hazards ever causing harm to the public, and the consequences even if they do, will generally be so low as to mean they present a low risk using any accepted risk assessment method.
But we must not forget that for any of these substances or processes to cause harm, there needs to be a proven exposure route. Whilst there may be a source of harm, and a receptor that can be impacted, unless there is a pathway connecting the two, harm cannot result.
Secondly, Britain’s history of oil and gas extraction doesn’t indicate a problem
The Wytch Farm facility in Dorset is Western Europe’s largest onshore oil field. Located on the southern shore of Poole Harbour, it includes a Site of Special Scientific Interest (SSSI) and forms part of a World Heritage Site.
Decades of operation there have had no identifiable adverse impact on the local environment, property prices or the health of people in the surrounding communities.
And yet the techniques of drilling wells, including horizontally (Wytch Farm previously held the record for the world’s longest horizontal well, reaching 10 kilometres) using drilling muds and fluids to stimulate to flow of hydrocarbons, are the same as those we can expect in shale gas exploration and development.
Wytch Farm isn’t the only place where hydrocarbons are extracted – and have been for decades – without any evidence of so-called ‘cancer clusters’, birth defects or any of the other health impacts nearby according to a search of publicly available online records compiled by Public Health England (try for yourself here where, for Wytch Farm, you’ll find that on all incidences of cancer, public health outcomes are not significantly different than the national average. Just select E05003733 – Wareham; Purbeck, Dorset on the map).
And, thirdly, it’s a mistake to compare the US experience with that we can expect in the UK
By referencing studies from the US, shale gas opponents give the casual reader the impression that the situation is, or will be, the same here. But there are several, marked differences that mean the UK experience is likely to be much better than that seen across the Atlantic:
For a start, our regulatory system is more robust. It is applied uniformly across the country, whereas individual states in the US can decide their own laws – with some being far weaker than others.
In the UK, operators have to seek permission from the Environment Agency before they can introduce any fluids or chemicals into the ground under rules designed to protect groundwater resources – there is no ‘Halliburton Loophole’ here, unlike in the US, where oil and gas companies conducting hydraulic fracturing were exempted from certain provisions of the Safe Drinking Water Act. It’s also worth noting that, in the remote areas where shale gas extraction takes place in the US, it is common for homeowners to extract their own water from wells on their property, whereas in the UK, the 50,000 or so private water wells notified to the Drinking Water Inspectorate only supply around 1% of total drinking water – the rest being supplied via pipe by public utility companies from above-ground sources like reservoirs, meaning the risk of water supplies being compromised here is significantly lower.
Allied to the point above, it’s vital to recognise that fears about hundreds of chemicals being used in ‘toxic cocktail’ are just unfounded in the UK. So far, at the only shale gas well to have been hydraulically fractured (at Preese Hall in Lancashire) the only additives used were a Polyacrylamide friction reducer (a non-hazardous polymer often used as a flocculant to remove solids in drinking water treatment and that readily biodegrades) and a salt tracer. Although it’s true that much larger ranges of chemical additives have been used in the US, partly as a result of weaker legislation, it’s also true that operators have been experimenting with less chemicals and finding that it improves gas yields.
Obsolete fracturing fluid left underground
People are right to note that a proportion of the injected fracturing fluid remains in the target formation and doesn’t flow back to the surface immediately after hydraulic fracturing has been performed. However, what we don’t often hear is that over the 20-30 year producing life of a shale gas well, all of the injected fluid will eventually return to the surface to be taken away for safe treatment and disposal. In the meantime, we needn’t be concerned about this fluid escaping, as some suggest it might, and that’s because the shale rock, whilst porous, is virtually impermeable which is why it needs to be stimulated to get the gas out. The over-pressure from the surrounding rock, and lack of permeability, means the fluid – and gas, for that matter – only has once place to go, and that’s to the low pressure area of the well.
Mining waste permits
UK operators, in applying for the separate permits they need to manage waste from what are considered ‘mining operations’, also have to declare the composition of any drilling muds and fracturing fluids they plan to use, along with the expected composition and quantity of any wastes. They also have to set out their arrangements for managing the same, and it is all a matter of public record – in fact, the public are even invited to consult on the permit applications. This isn’t the same in the US.
Environmental Impact Assessment
Companies here are now expected to undertake detailed Environmental Impact Assessments (EIA) before any drilling can take place. These assessments make sure that environmental issues are raised when a project or plan is first discussed and that all concerns are addressed as it gains momentum through to implementation. Recommendations made by the EIA may necessitate the redesign of some project components, require further studies, suggest changes which alter the economic viability of the project, or cause a delay in project implementation. Again, this is not yet a requirement in the US, where in some states it’s possible to obtain all the necessary regulatory approvals to drill within two weeks of securing a lease granting access to a landowner’s property.
Waste storage and treatment
In the UK, unlike in the US, wastewater will never be stored in open impoundment pits; this would simply not gain regulatory approval. Instead, it will be stored in above-ground tanks (which can be more easily inspected for leaks, prompting an appropriate and speedy response where required) that are provided with adequate secondary containment to capture any spills and prevent them from reaching the surrounding environment. Impoundment pits appear to be the biggest source of pollution incidents linked to shale gas extraction in the US. Another significant difference is that wastewater will undergo appropriate treatment in the UK, after which it will eventually be safely released back into the environment to once again become part of the water cycle, whereas in the US, it is typically injected into underground disposal wells.
Flaring unwanted gas will only happen for a relatively short duration of about 30 days per exploration well, and it’s only ‘unwanted’ because there is too much to use on site, but too little and for too short a time to warrant the investment and local disruption of installing a pipe connection to the national transmission system. The flares used in the UK will be low level ground flares, with an enclosed flame so as to minimise light and noise pollution. The gas is burned at temperatures exceeding 800 degC, leading to at least a 98% methane destruction efficiency and giving rise to water and carbon dioxide emissions – not the nasty vapours some claim. It is worth noting that this gas is the same as the gas burned on stoves in kitchens throughout the country, only that takes place indoors with no process controls and substantially less ventilation. In the US, it is admittedly very different in some places: their flare design sees huge naked flames lighting up the night sky, and in remote North Dakota – where they’re producing oil from shale – gas that is co-produced with the oil is cheaper to flare than it is to develop the pipeline infrastructure to get the gas away.
Trusting the experts
Public Health England, the government health watchdog, conducted a review of shale gas and fracking that was published in 2014 and you can find its report here. It concluded that ‘the currently available evidence indicates that the potential risks to public health from exposure to the emissions associated with shale gas extraction will be low if the operations are properly run and regulated. In order to ensure this, regulation needs to be strongly and robustly applied.’ We need to trust our own experts.