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NATURAL GAS development


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Marcellus Shale Drilling

The Marcellus Shale is a black shale formation extending deep underground from Ohio and West Virginia into Pennsylvania and southern New York which is now being exploited for the presence of natural gas.  The deposits located under Pennsylvania are reported to represent the largest natural gas reserves in the world. With the introduction of hydraulic fracturing in 2007, a sizeable and growing drilling industry has developed with thousands of current wells and additional thousands planned.  These wells are often located near residential areas, and there are growing concerns among the public, the media, and researchers about environmental contamination of water and air from drilling operations and disposition of solid and liquid waste.  These concerns have raised numerous questions about adverse health consequences associated with drilling activities.  As the industry expands, these public health concerns are likely to grow.  The Pennsylvania Department of Health (PADOH) will be expected to address these public health concerns.  

Natural gas drilling and extraction from the Marcellus Shale involves a complex process that includes preparation of the drilling site for operations; drilling deep into the bedrock (approximately 8-10,000 feet below the surface with creation of an extensive deep-well network of horizontal pathways); hydraulic fracturing (or fracking) the rock to release the gas; capturing the natural gas; and collecting, disposing or recycling of flowback water and drill cuttings.  The fracking process uses a combination of water, sand, and chemicals injected underground under high pressure, and involves massive volumes of water.  Each company uses a different combination and composition of chemicals and employs different methods for waste water disposition.  Fracking was first used for natural gas extraction in Colorado, Wyoming, and Texas, and has now spread to other parts of the country, including the south- central and northeastern states.  Wherever natural gas drilling is introduced, questions are inevitably raised about the possible environmental and public health effects on people living near these sites and on the workers involved in the industry.  More research must be done to address these important questions. 
Unconventional Oil and Natural Gas Drilling
Health Complaints Registry
Unconventional natural gas drilling has raised concerns about the health of the people in the communities where drilling activities are taking place. The division of Environmental Health Epidemiology has developed a registry for collecting health-related concerns of citizens associated with unconventional oil and natural gas development in Pennsylvania. Submission of information to this registry is voluntary. The information collected will be kept confidential (subject to the Health Insurance Portability and Accountability Act of 1996) and will be used to better track and respond to health complaints from citizens and may be used for future epidemiological studies. As part of the registry, the department will evaluate environmental data to develop recommendations to protect public health and to alleviate unwarranted fear from concerned citizens. However, the department is an advisory agency, not a regulatory one, and relies on the Department of Environmental Protection or private companies to collect environmental samples. Please contact the division of Environmental Health for additional information.

Potential Health Effects

There are several pathways of potential exposure to toxic chemicals from the fracking process.  These include contamination of drinking water, including private wells, when geologic fractures extend into groundwater or from leaks from the natural gas well into the groundwater.  Drilling fluid, chemical spills, and disposal pit leaks may also contaminate surface water supplies. Methane contamination of private drinking water wells has been associated with proximity to drilling sites. While many drilling fluids used in the drilling process are proprietary, chemicals that have been found in the environment include benzene, toluene, ethyl benzene, and xylene.  In addition, deep earth minerals and elements may be brought to the surface with the flowback water, including arsenic, bromide, barium, strontium, and radiological compounds.  The fracking and deep earth compounds can cause a wide variety of adverse health effects in humans such as cancer and adverse effects to the reproductive, neurological, and endocrine systems.  Some populations (e.g. children, pregnant women) may be more sensitive to these impacts than others.

Air pollution is another pathway of public health concern.  This can result from diesel exhaust from machinery and trucks, and fugitive emissions from the drilling site. These air pollutants are related to a wide variety of human health effects including cancer, respiratory illnesses, cardiovascular effects, and acute symptoms such as wheezing and coughing. The pollutants include volatile organic compounds such as ground-level ozone and benzene.
Other public health concerns include noise pollution, increased vehicular injuries from the increased truck traffic associated with the drilling activities, and injuries and emergencies from well explosions or flooding. Noise may impact sleep and have other negative health consequences. Workers who return to their families after work may expose family members to contaminants.  Finally, there are mental health concerns related to disruption of rural communities and the influx of workers. The public health effects of these and other drilling-related activities issues have been minimally studied.