Assessing Unconventional Oil and Gas Exposure in the Appalachian Basin: Comparison of Exposure Surrogates and Residential Drinking Water Measurements

Abstract

Health studies report associations between metrics of residential proximity to unconventional oil and gas (UOG) development and adverse health endpoints. We investigated whether exposure through household groundwater is captured by existing metrics and a newly developed metric incorporating groundwater flow paths. We compared metrics with detection frequencies/concentrations of 64 organic and inorganic UOG-related chemicals/groups in residential groundwater from 255 homes (Pennsylvania n = 94 and Ohio n = 161). Twenty-seven chemicals were detected in ≥20% of water samples at concentrations generally below U.S. Environmental Protection Agency standards. In Pennsylvania, two organic chemicals/groups had reduced odds of detection with increasing distance to the nearest well: 1,2-dichloroethene and benzene (Odds Ratio [OR]: 0.46, 95% confidence interval [CI]: 0.23–0.93) and m- and p-xylene (OR: 0.28, 95% CI: 0.10–0.80); results were consistent across metrics. In Ohio, the odds of detecting toluene increased with increasing distance to the nearest well (OR: 1.48, 95% CI: 1.12–1.95), also consistent across metrics. Correlations between inorganic chemicals and metrics were limited (all |ρ| ≤ 0.28). Limited associations between metrics and chemicals may indicate that UOG-related water contamination occurs rarely/episodically, more complex metrics may be needed to capture drinking water exposure, and/or spatial metrics in health studies may better reflect exposure to other stressors.

Unconventional Oil and Gas Development Exposure and Risk of Childhood Acute Lymphoblastic Leukemia: A Case–Control Study in Pennsylvania, 2009–2017

“…and was subsequently applied in a study of UOGD-related drinking water exposure. 65 This exposure metric assumes that UOG wells that are located upgradient of a residence contribute more to exposure than downgradient wells, presuming that consumption or contact with groundwater from domestic wells is a major exposure source. The metric was calculated using buffer sizes of 2, 5, and around the maternal residence.…”

“…The metric was calculated using buffer sizes of 2, 5, and around the maternal residence. Our selection of buffer sizes was informed by the hydrological ( ) and epidemiological (5 and ) literature, 64 , 65 , 76 , 77 – 81 and facilitates comparison between the aggregate metric and the water pathway-specific metric and comparisons with previous epidemiologic studies. We conducted a subanalysis using this metric as the main UOGD exposure assessment variable.…”

“…This work builds on prior studies by incorporating a larger sample size, the use of cancer-free controls identified from birth records, and the use of UOGD-specific metrics, including a novel metric developed for capturing exposures through the water pathway. 64 , 65 …”

Groundwater Methane in Northeastern Pennsylvania Attributable to Thermogenic Sources and Hydrogeomorphologic Migration Pathways

“…Methane isotopes were analyzed at the UC Davis Stable Isotope Facility. The measurement of dissolved ion species, the construction of spatial metrics and topographical classes, and the collection of pre-drilling data are also discussed in the Supporting Information and presented in other publications. − Any referenced pre-drilling data were acquired from the Shale Network database , and matched with our sampling locations or provided by the homeowners.…”

Study on the Relationship between the Relative Molecular Mass of a Polymer Clay Stabilizer and the Permeability of a Tight Reservoir

“…With the continuous growth of global oil and gas demand, more and more countries gradually shift their focus to the exploration and development of unconventional oil and gas resources. 1 , 2 Tight oil and gas, which are kind of unconventional oil and gas recourses, refer to hydrocarbons buried in tight reservoirs, which are characterized by the permeability equal to or less than 0.1 × 10 –3 μm 2 . 3 , 4 Because of their low permeability, hydraulic fracturing is the most important stimulation technology to improve oil and gas production.…”