The Effects of Hydraulic Fracturing Activities on Birth Outcomes are Evident in a Non-Individualized County-Wide Aggregate Data Sample from Colorado

Abstract

Background: There is growing concern about the recent increase in oil and gas development using hydraulic fracturing. Studies linking adverse birth outcomes and maternal proximity to hydraulic fracturing wells exist but tend to use individualized maternal and infant data contained in protected health care records. In this study, we extended the findings of these past studies to evaluate if analogous effects detected with individualized data could be detected from non-individualized county-wide aggregated data.Design and Methods: This study used a retrospective cohort of 252,502 birth records from 1999 to 2019 gathered from a subset sample of 5 counties in the state of Colorado where hydraulic fracturing activities were conducted. We used Generalized Linear Models to evaluate the effect of county-wide well density and production data over unidentified birth weight, and prematurity data. Covariates used in the model were county-wide statistics sourced from the US Census.Results: Our modeling approach showed an interesting effect where hydraulic fracturing exposure metrics have a mixed effect directional response. This effect was detected on birth weight when well density, production and their interaction are accounted for. The interaction effect provides an additional interpretation to discrepancies reported previously in the literature. Our approach only detected a positive association to prematurity with increased production.Conclusions: Our findings demonstrate two main points: First, the effect of hydraulic fracturing is detectable by using county-wide unidentified data. Second, the effect of hydraulic fracturing can be complicated by the number of operations and the intensity of the activities in the area.

Associations between proximity to gas production activity in counties and birth outcomes across the US

“…Our results align with other studies that found associations between exposure to NGD production with decreased birth weight ( Apergis et al, 2019 , Cushing et al, 2020 , Deziel et al, 2020 , Tran et al, 2020 , Tran et al, 2021 , Willis et al, 2021 ), and increased risk of infants born LBW ( Apergis et al, 2019 , Deziel et al, 2020 , Tran et al, 2020 , Tran et al, 2021 ), or SGA ( Deziel et al, 2020 , Tran et al, 2020 , Tran et al, 2021 ). However, in others, associations have been mixed ( Cushing et al, 2020 , Erickson et al, 2021 ). Our results were inconsistent with prior literature that has reported a positive association between exposure to NGD production and preterm birth ( Cushing et al, 2020 , Deziel et al, 2020 , Gonzalez et al, 2020 , Tran et al, 2021 ).…”

“…There are multiple challenges in comparing this body of research related to methodological inconsistencies involving measurement of NGD production type, distance, and intensity of exposure. Similar to our approach, some studies have included both conventional and unconventional NGD ( Apergis et al, 2019 , Cushing et al, 2020 , Deziel et al, 2020 , Gonzalez et al, 2020 , Tran et al, 2020 , Willis et al, 2021 ), while others have focused on fracked wells ( Erickson et al, 2021 , Tran et al, 2021 ), or also included inactive wells ( Tran et al, 2020 ). We considered a woman to be exposed if she lived in a county that contained any NGD production because county was the lowest geographical identifier available on the birth certificate.…”

“…Finally, the measured intensity of NGD exposure also varies. Studies, including ours, have used production volume ( Erickson et al, 2021 , Tran et al, 2020 ), while others have used well counts or well density ( Apergis et al, 2019 , Cushing et al, 2020 , Erickson et al, 2021 , Gonzalez et al, 2020 , Tran et al, 2020 ), which does not capture volume. In sum, consistency in measurement is essential in order to synthesize findings and quantify the effects of NGD production on birth outcomes.…”

“…To our knowledge, this evaluation of the effects of prenatal exposure to NGD production on birth outcomes is the largest to date, with data on nearly 34 million births across 1984 counties from 28 states. While previous studies focused on individual, high-producing states ( Apergis et al, 2019 , Cushing et al, 2020 , Deziel et al, 2020 , Erickson et al, 2021 , Gonzalez et al, 2020 , Tran et al, 2020 , Tran et al, 2021 , Willis et al, 2021 ), examining exposure across all NGD-producing states enhances the generalizability of findings to infants across the US. Recognizing that minoritized communities suffer greater environmental injustices ( Boyce et al, 2016 ), we examined racial/ethnic disparities in NGD exposure and found that infants born to women of color have worse health outcomes than infants born to white women.…”

“…More recent studies have found similar associations with lower birth weight ( Apergis et al, 2019 , Cushing et al, 2020 , Tran et al, 2020 , Tran et al, 2021 , Willis et al, 2021 ), being born LBW ( Apergis et al, 2019 , Tran et al, 2020 , Tran et al, 2021 ), preterm birth ( Cushing et al, 2020 , Gonzalez et al, 2020 , Tran et al, 2021 ), and SGA ( Tran et al, 2020 , Tran et al, 2021 ). Other studies have found limited or mixed evidence of associations ( Cushing et al, 2020 , Erickson et al, 2021 , Tran et al, 2020 ). Despite more disadvantaged and minoritized communities experiencing greater environmental burdens ( Boyce et al, 2016 ), only a few studies have examined the effects of NGD exposure on disparities in birth outcomes by race/ethnicity or education.…”