Author Dr. Bernard D. Goldstein, MD and Jill Kriesky, PhD; University of Pittsburgh Graduate School of Public Health; Department of Environmental and Occupational Health
Conventional vs. Unconventional Gas Production
World natural gas supplies are much more abundant than previously perceived. As just one example, the Marcellus shale, a gas-bearing shale area in the northeastern United States, is believed to contain an energy content equivalent to three years of the current world use of oil. In large part this availability represents rapid advances in horizontal drilling and in a technology known as hydraulic fracturing, or hydrofracking, particularly of gas-containing shales and other non-conventional gas sources that are widely distributed worldwide. Stated simply, hydrofracking consists of injecting large volumes of water containing roughly 0.5-1.5% of a blend of fracking chemicals whose role is to help loosen the gas and prop open the channels through which the gas flows. In addition to North America, non-conventional sources of significant amounts of natural gas are believed to be obtainable by hydraulic fracturing in locations as diverse as Sweden, Poland, Russia, China, Australia and parts of Latin America.
Unfortunately, in the rush to develop this valuable resource, health and environmental considerations have been largely overlooked despite frequently voiced public concerns about degradation of air, water and land. Contributing to these concerns are seemingly incompatible statements about hydrofracking. On the one hand the public is told that this exciting new technology permits obtaining natural gas that was previously inaccessible; on the other hand industry claims that hydrofracking technology has been around for decades so there should be no concern. But whereas in the past hydrofracking was done in relatively shallow vertical wells, the current techniques use perhaps 100 times the amount of water in deeper wells that are bent horizontally within the shale layer. About 30-70% of this fracking fluid flows back to the surface.
Also causing confusion is the definition of hydrofracking as the successful release of water and chemicals deep underground. Industry is claiming, probably accurately, that the chemicals rarely move upward from the shale layer into the much shallower levels at which groundwater aquifers exist. But the public is concerned about contamination of groundwater that might occur from the time the land is leveled for a drill pad until the well is removed and the land restored perhaps decades later. It is confusing to read about groundwater contaminated with fracking chemicals released, for example, from a defective well casing, yet be told that hydrofracking does not contaminate groundwater.
Likewise contributing to public and scientific apprehension is secrecy about the fracking chemical constituents. Concern exists not only about the many individual components of the fracking mixture. Much more information is needed about the toxicity of the mixtures used in the different fracking fluid combinations and, perhaps even more importantly, of the flowback fracking fluids to which has been added potentially hazardous agents such as gas components, arsenic, radioactive compounds or the high salinity naturally present underground.
Some of the wide range of potential health and safety issues related to unconventional natural gas drilling are shown in the Table. It is not possible to discuss them all in this brief overview. Among the issues is the lack of regulatory authority to deal with multiple well sources which in aggregate may pose a threat to air and water but individually are below the regulatory threshold.
There are also potential health benefits resulting from the exploitation of these unconventional natural gas resources, particularly if the economic benefits result in better health practices and health care in the relatively disadvantaged rural communities in which the boom is occurring. Another potential health and environmental benefit could come from the lessening of the air pollution and global climate impact of coal that is replaced by natural gas. But a positive impact on global climate change requires that the natural gas drilling and distribution processes limit the release of methane – a controversial subject.
Very little is being done to narrow the uncertainties about the potential health impacts of unconventional natural gas development. This is evident from the finding that of the 52 members of three US committees established to provide advice about natural gas drilling established in 2011 by President Obama, the Governor of Maryland and the Governor of Pennsylvania, a grand total of zero have any background in environmental public health or in any other health area. Similarly, the US Environmental Protection Agency’s fracking research agenda will not begin studying health issues until at least 2014. Yet it is certain that there will be continuing health and environmental complaints attributed to natural gas drilling and to hydrofracking.
The breadth of the issues involved in decision-making about the boom in unconventional natural gas development and hydrofracking argue for serious consideration of sustainability issues. Effective decisions require a systematic approach that encompasses environmental, economic, social and health dimensions; and that consider longer term issues – including what happens to affected communities after the gas runs out. Until that is done, we can expect that much of the societal benefit of unconventional natural gas development may be lost in the headlong rush to exploit these valuable resources at the cost of the environment and of human health.
Pathways for adverse health effects resulting from unconventional natural gas drilling
– Worker health and safety;
– Air pollution;
– Water pollution;
– Soil pollution;
– Noise pollution;
– Community safety: traffic, explosions, fires, crimes;
– Psychosocial disruption;
– Lack of sustainability;
– Global climate change;