摘要：Objectives. To investigate race and poverty in areas where oil and gas wastewater disposal wells, which are used to permanently inject wastewater from hydraulic fracturing (fracking) operations, are permitted. Methods. With location data of oil and gas disposal wells permitted between 2007 and 2014 in the Eagle Ford area, a region of intensive fracking in southern Texas, we analyzed the racial composition of residents living less than 5 kilometers from a disposal well and those farther away, adjusting for rurality and poverty, using a Poisson regression. Results. The proportion of people of color living less than 5 kilometers from a disposal well was 1.3 times higher than was the proportion of non-Hispanic Whites. Adjusting for rurality, disposal wells were 2.04 times (95% confidence interval = 2.02, 2.06) as common in areas with 80% people of color or more than in majority White areas. Disposal wells are also disproportionately sited in high-poverty areas. Conclusions. Wastewater disposal wells in southern Texas are disproportionately permitted in areas with higher proportions of people of color and residents living in poverty, a pattern known as “environmental injustice.” Waste disposal is an enduring public health problem. Throughout history, waste disposal has often resulted in environmental pollution and, consequently, harm to human health. 1 Waste disposal sites are often unequally distributed and located away from the individuals who receive most of the benefits associated with activities that generate the waste. 2–4 Nationwide, a disproportionate number of waste disposal facilities are sited in communities of color, a pattern known as “environmental injustice.” 5,6 Rural areas, whose residents often face political marginalization, have often been burdened with waste from urban and industrial sources. 7,8 Waste facilities, and their unequal distribution, can adversely affect the health of communities in which they are sited. 9 Over the past decade, the United States has experienced a dramatic increase in unconventional oil and gas (UOG) development. This technique combines horizontal drilling with the pressurized high-volume injection of fluids to fracture the underground shale and release the oil or gas trapped within, a process known as hydraulic fracturing or “fracking.” Approximately 100 000 UOG wells have been drilled throughout the United States as of 2012. 10 Each hydraulically fractured well requires an estimated 11 to 19 million liters of water for drilling. 11 In these wells, sand and a complex mixture of chemical additives, many associated with known adverse health risks (e.g., endocrine disruption and cancer), are injected along with the water. 12 For every well, an average of 5.2 million liters of fracking fluid returns to the surface as wastewater. 13,14 The management of this wastewater presents a significant public health problem. 12 UOG wastewater contains chemical additives used in the drilling process, along with salts, heavy metals, radioactive material, and hydrocarbons from the subsurface. 15–18 The vast majority of this wastewater is disposed of via pumping into underground disposal wells. 19 Wastewater from oil and gas operations is not considered a hazardous material under federal law and is therefore allowed to be disposed of in class II injection wells. These wells are subject to fewer safety requirements than are hazardous waste (class I) wells and are structurally similar to production wells. UOG wastewater is typically pumped directly back into the subsurface, without any treatment or containers for waste. The term “disposal well” refers to all permitted underground wells for injecting oil and gas wastewater. Wastewater injected into disposal wells may, in some circumstances, migrate to the surface or into freshwater aquifers. 20–23 Toxins can migrate to groundwater through leaks, cracks, or nearby abandoned wells, and multiple cases of groundwater contamination associated with wastewater disposal wells have been identified. 24 For example, in southeastern Texas, groundwater near oil and gas disposal wells was found to have higher concentrations of chloride and bromide than was groundwater farther away. 25 In addition, there is growing evidence regarding the seismic hazards associated with the practice of disposing of fracking wastewater into injection wells. 10,26,27 In northern Texas, the epicenters of small earthquakes were found to be related to disposal well proximity. 28–30 The environmental justice dimensions of UOG development and the fate of its waste products have yet to be characterized. One recent study of the Marcellus shale in Pennsylvania found that UOG operations were concentrated in areas with higher poverty rates but did not find a difference with respect to race. 31 The Eagle Ford shale formation covers 26 counties in the southern and eastern stretches of Texas ( Figure 1 ). Eagle Ford ranked first for the volume of oil produced and fourth for gas production in the United States in 2013. 32 More than 1000 new disposal wells have been permitted in this region since 2007, the start of the shale boom. Unlike in Pennsylvania and other major regions of UOG drilling, a large proportion of people of color live in the rural counties overlying the formation. 33 Open in a separate window FIGURE 1— Area and Location of Permits for Unconventional Oil and Gas Extraction Wells: Eagle Ford Shale Region, TX, 2007–2014 In 2013, the community-based organizations Centro por la Justicia and Southwest Workers’ Union, along with local residents, organized a series of meetings to discuss the social, environmental, and human health dimensions of the extraction, production, and ultimate disposal of oil, natural gas, and its byproducts in the Eagle Ford area. One concern raised at these meetings was the siting of new disposal wells for wastewater with respect to race and ethnicity and their potential impact on local drinking water supplies. The local organizations invited us to partner with them to investigate the racial, ethnic, and economic composition of communities receiving UOG waste in the region.
