Skip to content

Difficulties in assessing the risks of hydraulic fracturing and shale gas extraction: new study shows correlation between birth defects and proximity to gas wells in Colorado.

Natural gas extraction is associated with several known teratogens. A study published in the journal Environmental Health Perspectives on January 28th by researchers from the Colorado School of Public Health and the Department of Epidemiology of Brown University, USA, finds that for those babies born of mothers living with greater density of natural gas wells within a ten mile radius of their residence, there was an increase in congenital heart defects, and a possible link with increase in neural tube defects. 1
This is significant for current debates about the future of methods to extract shale gas inland in the UK, including the use of hydraulic fracturing (or fracking as it is more commonly known). Fracking involves a method for extracting natural gas from impermeable rocks deep within the earth by deep drilling, firstly vertically, then horizontally, and the injection of a mixture of water, sand and chemicals at high pressure into the wells to cause fissures into the rock (hydraulic fracturing) through which natural gas can escape up to the surface. The aim is that the fracturing will take place beneath the water table so that the water supply is not polluted by the mix of chemicals, methane gas and rock that are produced. The water sand and chemical mix that had been injected into the well is then partially recovered (it is never possible to recover all of it) and this waste fracking fluids, complete with fragments of rock from deep in the earth, must be disposed of. The technology requires that large numbers of wells are drilled in order to extract the gas, and requires the transportation of millions of gallons of water and chemicals to the drill, as well as some method of disposal of the waste. (The precise method of disposal for proposed UK fracking is not yet clear: in the States, evaporation pits are often used, but these are, for good reason, illegal in the EU.)
The debate about the safety of fracking is complex and it is important to tease apart some of the many points that may possibly muddy the debate. One of the difficulties is collating and assessing evidence of harm; another difficulty is in assessing how we extrapolate data of risks and benefits from one situation to another, when there may be variations in geography, geology, techniques used, chemicals used, regulations, and law. There is much to consider, so here I just discuss a couple of points to indicate how complex the debate is. One main lesson should be that simplistic assurances of lack of risk from fracking should be listened to with caution.

Firstly, in assessing the safety of the technology, it is necessary to draw upon a wide range of expertise. It is no good, for example, looking only at whether the geology suggests that there is a danger that gas or the mix of chemicals used in the fluids injected deep into the ground might in principle seep into the water table. It’s necessary also to call on experts from engineering. To take just one example of the many aspects of engineering that need to be assessed, the wells drilled deep into the ground are given concrete seals. A geologist might have an opinion on the permeability of the rock, and the distance to the water table, but it’s an engineer who will be able to tell you the likelihood that the concrete seal will break down, and how fast this is likely to happen, and in what percentage of the many hundreds or thousands of wells needed this is likely to happen. Because if there are chemicals injected into fracking wells that really ought not to get into the water supply, then we need to be sure that there is no way that they can get in there. Otherwise, it’s like saying, ‘Don’t worry, there’s only one hole in the balloon’. Likewise, different sorts of experts – on toxicology, epidemiology, and on the movement of chemicals through the water supply and in the air – will be needed to tell us what the long term effects of fracking might be on the environment and on human, animal and plant health. Thus, assessments of safety need to be made not simply by citing expert evidence informed by one aspect of the debate, but by all relevant aspects, and with a view to the particular situation under consideration.
Secondly, in gathering up any evidence, it might seem helpful to turn to a place like the US where this technology has been used for many years now. But it’s vital to remember that the evidence may not be as forthcoming as one might hope, because of different regulations which apply to the oil and gas industry in the USA and which have hampered the gathering of data on pollutants which might otherwise have been available. Popularly known as the ‘Halliburton loophole’, the Energy Policy Act of 2005 makes fracking exempt from the Clean Water Act, so that ‘water, gas, or other material which is injected into a well to facilitate production of oil and gas’ do not count as pollutants. Therefore, environmental reporting requirements do not apply. Moreover, there are numerous reports that individuals affected by gas extraction who have been given compensation for injuries or loss have signed gagging orders.
The mix of chemicals that companies use in the water injected at high pressure into frack wells is a proprietary secret in the USA and there is no general right to know what is in it. The public are often ‘reassured’ that these are just chemicals that one might find in an ordinary household … to which I would reply, ‘which chemicals?’ Being a ‘household chemical’ doesn’t make it environmentally safe. Do you take milk and sugar in your draincleaner?
What this all means is that there has been difficulty in collecting systematic evidence in the States, and of course, the sort of evidence contained in the recent report demonstrating an association with proximity to higher density of gas wells and an increase in birth defects is evidence that will take years to build up and gather. There is however a mounting collection of such evidence, such as the Pennsylvania Alliance for Clean Water and Air List of the Harmed2. And it’s also, of course, ‘after the horse has bolted’ evidence. For wouldn’t it be better to have a quicker and clearer idea of the release of any pollutants into the air and the water, than to wait and see how many babies get damaged, and how many sick people have fracking chemicals in their blood?
And what this means for countries like the UK is that assurances that there is little or no evidence of harm from shale gas extraction in the US must be taken with caution, given the difficulty of gathering and assessing evidence.
However, conversely, the difference between the US and the UK case has also been used to claim that evidence of harm from shale gas drilling in the US is not relevant to the UK, precisely because regulations are tighter here in the UK. But this response must also be treated with care. For to dismiss evidence of potential harms entirely with assurances of better regulation, we would need to be certain how, precisely, UK regulation was going to ensure that no such problems could occur here. And we should need to know for certain that such regulation was not going to be chipped away at, and we should need to know that such regulation was going to be adhered to. Yet recent headlines such as ‘MP demands answers on why waste water from fracking was dumped into the Manchester Ship Canal’3 fail to reassure. Regulation needs to cover not just extraction of gas, but also the treatment of wells after use, and the disposal of waste products. This will be highly complex, given the chemical mix used in fracking, and given complications such as the potential for fracking in some areas to bring radioactive materials to the surface.
There is also a very obvious difference in situation between gas extraction in areas with low density populations and those with high density populations, such as the area of England that often now laughingly calls itself, in response to a recent public insult, the ‘Desolate North’. To extract shale gas by fracking requires hundreds, if not thousands, of wells to be drilled. It’s not always obvious from diagrams either, that after boring the initial well, horizontal wells are drilled out in all directions, about eight in all. The population of Britain is much denser than that of many areas in the world where fracking has already taken place, such as rural southern Queensland and many areas of the USA. To give one example, Barton Moss, where there is currently exploratory drilling under way, and which has been the subject of protests in the last few months, is in an area where a large population live within the ten mile radius that the recent study from Colorado showed could be associated with an increase in birth defects. One would certainly hope that the factors that are linked with this increase in risk in Colorado would not be present if proposed drilling does indeed go ahead in this area. Barton Moss is within eight miles of the centre of Manchester (population in total over 500,000), and a ten mile radius will take you into Bolton, Bury, Salford, Trafford and some of Warrington too. Salford alone has a population of about 220,000, Trafford about 227,000, Bolton almost 140,000, Bury 60,000. Other areas which are within a ten mile radius of this densely populated area of a densely populated country include Irlam and Cadishead , Hollins Green, Rixton, Glazebrook, Glazebury, Culcheth, Risley, Birchwood, Leigh, Astley, Ellenbrook, Worsley, Boothstown, Winton, Monton, Eccles, Peel Green, Barton, Hope, Ellesmere Park, Swinton, Moorside, Wardley, and Little Hulton. One would hope that risks are assessed carefully and impartially, and with an eye to caution, before proceeding with any rush to exploit shale gas resources.

1. ‘Birth Outcomes and Maternal Residential Proximity to Natural Gas Development in Rural Colorado’, Lisa M. McKenzie, Ruixin Guo, Roxana Z. Witter, David A. Savitz, Lee S. Newman, and John L. Adgate , Environmental Health Perspectives, National Institutes of Environmental Health Sciences, National Institute of Health, 28th January 2014,
2. Pennsylvania Alliance for Clean Water and Air List of the Harmed available here:
3. ‘MP demands answers on why waste water from fracking was dumped into the Manchester Ship Canal’, Messenger, Friday 31st January:

Share on

3 Comment on this post

  1. Number of factual errors:
    Chemicals have not been a proprietary secret in USA for several years, and there is certainly no desire or wish to have that in Europe
    Recent advances in technology mean that there would only be one or two drilling rigs per 100 square kilometres. There are no plans to industrialise the UK landscape as that would make the exercise uneconomic
    Population density of Europe is based on a far higher concentration of population in towns and cities. UK/EU Rural areas often have similar, or even lower, population densities as areas in USA. First US shales took place in Fort Worth, one of the top 10 US cities by population. Again, the development in the UK is likely to produce the same amount of gas using only 10% of the wells used in Fort Worth as recently as 2010

    Finally, is peer review an alien concept to Oxford or can anyone post anything? I suggest reading this to understand this issue

  2. This is a good review of a report that I must say is quite shocking. There are a couple of points I would take issue with. I have been reading quite a lot about this, and have 12 years of field experience on wells, dealing with a lot of leaking and damaged ones. There would appear to be no doubt that toxic pollutants have entered the environment. The practice in the States is to use an open lined pit to store fluids including flow back fluids that contain low levels of radioactive materials (NORMS). Many of the pollution incidents can be traced back to leaking pits, or flooded pits. Flowing back fluids into an open pit also means that toxic volatile materials also can escape. As you note it is illegal to do that in the UK. There have been no documented cases of injected fluids penetrating water tables through directly through the rocks. Many layers of these rocks are either very impermeable, or are cap rocks. This idea alas seems to be gaining ground among the anti fracking lobby, even though there is no science to support this. The source rocks are thousands of feet below any water table that we would use. In addition it seems that in testing wells, methane containing pollutants is often vented to the atmosphere in the US. Flaring this would be much safer. Regarding surface leaks, this is well documented but crucially this would not involve the toxic fracking fluids. They are injected by displacement across a perforated area of casing, and the pressure and fluids is only present in the drill pipe and deep underground. Surface leaks could lead to seepage of methane, but not of fracking fluids. Cuadrilla well designs seems to be industry best practice with the crucial cement seal. Regarding the Manchester Shipping Canal dumping, reading the newspaper report, this would seem to be a mistake in regulation, as the licencing conditions were changed. As such this would seem to be a cock up. All fluid disposal has to meet HSE and EA approval. I cannot see why companies would want to avoid this as the potential for crticism is huge.

Comments are closed.