Abstract
Oil and gas (O&G) facilities emit air pollutants that are potentially a major health risk for nearby populations. We characterized prenatal through adult health risks for acute (1 h) and chronic (30 year) residential inhalation exposure scenarios to nonmethane hydrocarbons (NMHCs) for these populations. We used ambient air sample results to estimate and compare risks for four residential scenarios. We found that air pollutant concentrations increased with proximity to an O&G facility, as did health risks. Acute hazard indices for neurological (18), hematological (15), and developmental (15) health effects indicate that populations living within 152 m of an O&G facility could experience these health effects from inhalation exposures to benzene and alkanes. Lifetime excess cancer risks exceeded 1 in a million for all scenarios. The cancer risk estimate of 8.3 per 10 000 for populations living within 152 m of an O&G facility exceeded the United States Environmental Protection Agency's 1 in 10 000 upper threshold. These findings indicate that state and federal regulatory policies may not be protective of health for populations residing near O&G facilities. Health risk assessment results can be used for informing policies and studies aimed at reducing and understanding health effects associated with air pollutants emitted from O&G facilities.
Highlights
Horizontal drilling and high-volume hydraulic fracturing have resulted in a dramatic increase in the number of oil and gas (O&G) wells located on a single pad.[1,2] It is common forO&G well sites to contain 20 to 40 wells, related infrastructure, and tank batteries to store and/or pipelines to transport petroleum products and exploration and production (E&P) waste.[3]
The mean ambient benzene, toluene, ethylbenzene, total xylene and total alkane concentrations from the 1-min samples collected within 152 m of the nearest O&G facility were 41, 34, 35, 32, and 86 times higher, respectively, than the mean from 1-min samples collected further than 1600 m from the nearest O&G facility (p < 0.05, Figure 3)
For the 3, 72, and 96-h samples (Figure 3b and Table S6b), the timeweighted average (TWA) mean concentration from the 3-h samples collected in Platteville (247 m from nearest O&G facility) was compared to the mean concentration from the 72- and 96-h samples collected in Boulder (>1600 m from nearest O&G facility) and Eastern Boulder County (448−625 m from nearest O&G facility)
Summary
Horizontal drilling and high-volume hydraulic fracturing have resulted in a dramatic increase in the number of oil and gas (O&G) wells located on a single pad.[1,2] It is common for. The few previous human health risk assessments conducted in areas with O&G development have used results from ambient air samples to predict the risk for both noncancer and cancer health effects in the surrounding population.[8,26,27] Risks for noncancer health effects have been expressed as semiquantitative hazard indices (HI), and cancer risks have expressed as risk in excess of the baseline lifetime cancer risk for Americans of 44 per 100 (lifetime excess cancer risk).[28] The previous assessments indicate the potential for short-term respiratory, neurological, hematological, and developmental effects and elevated estimated lifetime excess cancer risk for populations living within approximately 800 m of O&G well pads,[8] while the potential for chronic noncancer health effects and lifetime excess cancer risk are lower for populations living further from O&G sites.[8,26,29,30] One important shortcoming of previous risk assessments is that they did not consider shortterm and repeated nighttime peak exposures They did not explicitly address childhood exposures or incorporate findings from the most recent studies on health effects associated with ambient benzene exposure. The goal of this analysis is to characterize prenatal through adult noncancer and cancer health risks from both short-term (acute) and long-term (chronic) residential exposures to NMHCs measured in CNFR O&G development areas and how health risks vary with proximity to O&G facilities
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