Congenital Anomalies Associated with Oil and Gas Drilling, Resource Extraction, and Water Production: A Population-Based Retrospective Cohort Analysis

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Background: Oil and gas extraction-related activities produce air and water pollution that contains known and suspected teratogens (e.g. benzene, methanol, diesel particulate matter) that could create an increased risk of congenital anomalies (birth defects). Using a population-based birth cohort in Texas, one of the highest producers of oil and gas, we investigate associations between in utero exposure to oil and gas extraction and odds of congenital anomalies.Methods: We acquired birth certificate information in Texas between 1999 and 2009 (n=2,234,138), which was linked to the statewide congenital anomaly surveillance system (n=86,315 cases). Using full address data, we attached maternal residences at delivery to the coordinates of active oil and gas extraction sites. To examine different aspects of extraction processes, we built residential exposure metrics using tertiles of inverse distance-squared weighting within 5km: drilling site count, gas production, oil production, and water production. In logistic regression models, we calculate odds of any congenital anomaly and 10 specific organ sites using two control groups: 1) mothers living 5-10km of an active well, and 2) 5km of future drilling sites (but which is not yet operational). All models controlled for a comprehensive set of maternal characteristics and spatial- temporal variation to control for potential unmeasured contextual factors.Results: Using the temporal control group, we observe increased odds of a congenital anomaly associated with drilling-related exposures in the top tertile: 1.26 (95% CI: 1.21, 1.31) for site count; 1.08 (95% CI: 1.04, 1.12) for oil; 1.19 (95% CI: 1.16, 1.23) for gas, and 1.17 (95% CI: 1.14, 1.20) for water. Associations are similar, but attenuated, with the spatial control group. For specific organ sites, we observe that cardiac and circulatory defects are consistently associated with all metrics.Conclusions: Increased odds of congenital anomalies were consistently associated with drilling-related exposures in this large population-based study.