Assessing Exposure to Unconventional Oil and Gas Development: Strengths, Challenges, and Implications for Epidemiologic Research

Abstract

Purpose of Review Epidemiologic studies have observed elevated health risks in populations living near unconventional oil and gas development (UOGD). In this narrative review, we discuss strengths and limitations of UOG exposure assessment approaches used in or available for epidemiologic studies, emphasizing studies of children’s health outcomes. Recent Findings Exposure assessment challenges include (1) numerous potential stressors with distinct spatiotemporal patterns, (2) critical exposure windows that cover long periods and occur in the past, and (3) limited existing monitoring data coupled with the resource-intensiveness of collecting new exposure measurements to capture spatiotemporal variation. All epidemiologic studies used proximity-based models for exposure assessment as opposed to surveys, biomonitoring, or environmental measurements. Nearly all studies used aggregate (rather than pathway-specific) models, which are useful surrogates for the complex mix of potential hazards. Summary Simple and less-specific exposure assessment approaches have benefits in terms of scalability, interpretability, and relevance to specific policy initiatives such as set-back distances. More detailed and specific models and metrics, including dispersion methods and stressor-specific models, could reduce exposure misclassification, illuminate underlying exposure pathways, and inform emission control and exposure mitigation strategies. While less practical in a large population, collection of multi-media environmental and biological exposure measurements would be feasible in cohort subsets. Such assessments are well-suited to provide insights into the presence and magnitude of exposures to UOG-related stressors in relation to spatial surrogates and to better elucidate the plausibility of observed effects in both children and adults.

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

“…The magnitude of the association was greatest among those children living within of UOGD and exposed during the perinatal period. This research adds to a growing body of work documenting adverse health effects associated with UOGD, particularly among children, 36 , 109 , 110 and provides additional support for more stringent setback policies and other public health measures to reduce exposures to UOGD.…”

“…At this time, the dominant stressor is not well understood. 36 Nonetheless, epidemiological studies should try to pinpoint specific exposure pathways underlying associations. Several recent studies of UOGD have explored metrics representing specific (rather than aggregate) routes of exposure, such as flaring, earthquakes, air pollution, and radioactivity.…”

“…Unconventional oil and gas development (UOGD), commonly referred to as hydraulic fracturing or “fracking,” is a complex process with the potential for releases of chemical and radiological contaminants into both water and air. 36 UOGD is a rapidly expanding source of energy and petrochemical production in the United States. Hydraulic fracturing, an important step in the UOGD process, involves pressurized injections of millions of gallons of water, chemicals, and proppant (e.g., sand) into underground rock formations to create small fissures, allowing natural gas to flow to the surface.…”

Applying the hierarchy of controls to oil and gas development

“…Setbacks also do not prevent the release of methane or other greenhouse gases that contribute to climate change, which indirectly introduces human health risks at local to global scales. Finally, increasing distance between OGD activities and human residential communities could place OGD infrastructure closer to wildlife communities, thereby shifting the burden to ecological rather than human health impacts (Deziel et al 2022b). To date, 23 states have adopted or are considering setbacks that vary widely and range from 100 ft (e.g.…”

Temporal Trends of Racial and Socioeconomic Disparities in Population Exposures to Upstream Oil and Gas Development in California

“…Each stage of production is associated with environmental stressors that may plausibly contribute to adverse health outcomes. These stressors include emissions of air pollutants, groundwater contamination, persistent noise and odors, seismic activity, and social disruption (Adgate et al., 2014 ; Deziel, Clark, et al., 2022 ; Garcia‐Gonzales, Shonkoff, et al., 2019 ). Assessing individual‐ or area‐level exposure to wells based on proximity provides a holistic indicator for the aggregate hazards associated with oil and gas development (Deziel, Clark, et al., 2022 ).…”