Maternal exposure to industrial air pollution and congenital heart defects: a case–control study

Congenital heart defects (CHD) are a leading cause of infant mortality, but the etiology of most cases is unknown, and the potential role of industrial pollution exposure is largely unexplored. There are no studies of CHD and pollution in Louisiana, a state with among the worst birth outcomes in the nation and relatively high levels of toxic industrial emissions. Our study aimed to investigate the possible relationship between industrial air pollution and CHD in southeast Louisiana, encompassing the region commonly referred to as Cancer Alley or the Mississippi River Industrial Corridor. We conducted a matched case-control study of industrial air pollution and CHD among infants in Louisiana Department of Health Regions 1–3 born from 2018 to 2021 ( n = 454 cases and 1,362 controls), using summed toxicity-weighted concentrations of 20 developmental toxins from EPA’s MicroRSEI dataset. We calculated CHD odds for the highest (> 75th percentile) and intermediate (10th to 75th percentile) pollution categories from a logistic regression conditioned on race, insurance status, and gestational timing. To eliminate confounding by insurance status, we excluded individuals with private insurance. We then compared chemical data distributions between cases and controls and, for select chemicals, calculated CHD odds. Among infants without private insurance, higher pollution levels were associated with increased odds of severe CHD, with response increasing as dose increased. These odds were 4.29 times higher (95% CI: 1.85, 9.91) and 3.09 times higher (95% CI: 1.35, 7.12) for infants from the most toxic areas and intermediate pollution areas, respectively, compared to low-pollution areas. Odds were relatively low among infants with private insurance and/or mild defects, potentially from incomplete case ascertainment. Limited sample sizes precluded comparisons for CHD types, except septal defects, which were generally non-severe and followed the same pattern as mild defects overall. Higher CHD odds were linked to benzene and formaldehyde, which had the highest toxicity weighted-modeled concentrations, but were also linked to toluene and the combined effects of 17 other developmental toxins. To our knowledge, this is the first study to investigate the relationship between air pollution and CHD in Louisiana. We found that industrial air pollution was associated with higher odds of severe CHD, with evidence of significant cumulative effects from multi-pollutant exposures.