title: Emissions of Polycyclic Aromatic Hydrocarbons from Natural Gas Extraction into Air.
abstract: Natural gas extraction, often referred to as "fracking", has increased rapidly in the United States in recent years. To address potential health impacts, passive air samplers were deployed in a rural community heavily affected by the natural gas boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. Levels of benzo[a]pyrene, phenanthrene, and carcinogenic potency of PAH mixtures were highest when samplers were closest to active wells. PAH levels closest to natural gas activity were comparable to levels previously reported in rural areas in winter. Sourcing ratios indicated that PAHs were predominantly petrogenic, suggesting that PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. At sites closest to active wells, the risk estimated for maximum residential exposure was 0.04 in a million, which is below the U.S. Environmental Protection Agency's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest from them. This work suggests that natural gas extraction is contributing PAHs to the air, at levels that would not be expected to increase cancer risk.
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: L Blair
authors.initials: LB
authors.lastname: Paulik
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Carey E
authors.initials: CE
authors.lastname: Donald
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Smith
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Lane G
authors.initials: LG
authors.lastname: Tidwell
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Hobbie
authors.affiliation: College of Public Health and Human Sciences, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Laurel
authors.initials: L
authors.lastname: Kincl
authors.affiliation: Department of Environmental Health, University of Cincinnati , Cincinnati, Ohio 45267, United States.
authors.forename: Erin N
authors.initials: EN
authors.lastname: Haynes
authors.affiliation: Department of Environmental and Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Anderson
mesh_terms: D000393:Air Pollutants; D004784:Environmental Monitoring; D006801:Humans; D059206:Natural Gas; D011084:Polycyclic Aromatic Hydrocarbons; D018570:Risk Assessment
chemical_list: D000393:Air Pollutants; D059206:Natural Gas; D011084:Polycyclic Aromatic Hydrocarbons