Popular epidemiology and "fracking": citizens' concerns regarding the economic, environmental, health and social impacts of unconventional natural gas drilling operations.

Pennsylvania sits atop the Marcellus Shale, a reservoir of natural gas that was untapped until the 2004 introduction of unconventional natural gas drilling operations (UNGDO) in the state. Colloquially known as fracking, UNGDO is a controversial process that employs large volumes of water to fracture the shale and capture gas; it has become a multi-billion dollar industry in Pennsylvania. We analyzed letters to the editor of the most widely circulated local newspaper in the most heavily drilled county in Pennsylvania (Bradford County) in order to characterize residents' concerns and their involvement in popular epidemiology--the process by which citizens investigate risks associated with a perceived environmental threat. We reviewed 215 letters to the editor that referenced natural gas operations and were published by The Daily Review between January 1, 2008 and June 8, 2013. We used NVivo 10 to code and analyze letters and identify major themes. Nvivo is qualitative data analysis software (http://www.qsrinternational.com/products_nvivo.aspx) that allows researchers to code and analyze "unstructured" data, including text files of any type (e.g., interview transcripts, news articles, letters, archival materials) as well as photographs and videos. Nvivo can be used to classify, sort, query, comment on, and share data across a research group. Letters demonstrated citizen engagement in beginning and intermediate stages of lay epidemiology, as well as discord and stress regarding four main issues: socio-economic impacts, perceived threats to water, population growth and implications, and changes to the rural landscape. Residents called for stronger scientific evidence and a balance of economic development and health and environmental protections. Citizens' distress regarding UNGDO appeared to be exacerbated by a dearth of information to guide economic growth and health, environmental, and social concerns. This analysis proposes locally informed questions to guide future surveillance and research.