4 December 2012

Gas fracking: do we understand the potential health consequences?


UNEP has just released a new bulletin on Hydrological fracturing (fracking). The document introduces the topic, and then analyses it in the context of climate change and energy consumption needs.  Among the  aspects addressed there are a few very relevant for HIA and public health practitioners. There is also a bibliography for those interested in further information.
Environmental and health concerns
UG exploitation and production may have unavoidable environmental impacts (see Figure 4). Some risks result if the technology is not used adequately, but others will occur despite proper use of technology (EU, 2011). UG production has the potential to generate considerable GHG emissions, can strain water resources, result in water contamination, may have negative impacts on public health (through air and soil contaminants; noise pollution), on biodiversity (through land clearance), food supply (through competition for land and water resources), as well as on soil (pollution, crusting). The sections below further outline the potential environmental and health impacts

Risk on public health
When occurring in densely populated areas, UG production raises several specific threats to well-being. The most direct concern is the risk of explosion from the construction of new pipelines (Rahm, 2011). Other consequences have a slower onset, such as release of toxic substances into air, soil and water. In Texas, emissions from shale gas operations are being checked for contaminants after blood and urine samples taken from household residents near shale wells revealed that toluene was present in 65% of those tested and xylene present in 53% (Rahm 2011). Both of these chemicals are commonly present in fracking fluid and known for being toxic. The biocide substances which are also contained in fracking fluid, and may be released during surface water leaks, can lead to serious damage to the surrounding habitat (IEA, 2012).
More common nuisances include noise pollution, primarily associated with drilling and fracking (which is a non-stop operation over several weeks), but also from truck transport (Rahm, 2011).
Fracturing fluid consists of large amounts of water mixed with chemicals and sand. In most countries the chemicals used in fracking fluid are considered trade secrets (Zoback et al., 2010). If companies are not required to publicly disclose the full list of chemicals used, assessing potential short- and long-term impacts on public health will be difficult. Colborn and others (2011) compiled a list of products (about 1000) used in fracking fluid. They carried out literature review on 353 chemicals and found that "more than 75% of the chemicals could affect the skin, eyes, and other sensory organs, and the respiratory and gastrointestinal systems. Approximately 40–50% could affect the brain/nervous system, immune and cardiovascular systems, and the kidneys; 37% could affect the endocrine system; and 25% could cause cancer and mutations." (Colborn et al., 2011).
Nonylphenol, for example, which is commonly used in fracking fluid, mimics estrogen, and can cause the feminization of fish, even at concentrations not detected by normal monitoring of the fluid (NYS-WRI, 2011). The consequence of the feminization of fish is an imbalance between male and female populations, resulting in a deficit of fertilization and potentially leading to a rapid decline of these fish populations.