A High Concentration of Polycyclic Aromatic Hydrocarbons in Umbilical Cord Tissue is Associated with an Increased Risk for Fetal Neural Tube Defects

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment and have detrimental effects on human health. Embryos are particularly susceptible to environmental insults such as PAHs. We examined the association between prenatal exposure to PAHs and the risk for fetal neural tube defects (NTDs). A case–control study was conducted with 119 NTD cases and 119 controls. A total of 16 PAHs in umbilical cord tissue, determined with gas chromatography–mass spectrometry, were used as in utero exposure markers. Logistic regression and Bayesian kernel machine regression (BKMR) were performed to evaluate the individual and overall effects of PAH exposure on the risk for NTDs, respectively. Median concentrations of 10 PAHs were significantly higher in cases than in controls. In logistic regression, concentrations of four PAHs above the median of all participants were significantly associated with an increased NTD risk, even when potential covariates were adjusted for: phenanthrene, 2.35-fold (95% confidence interval [CI] 1.04–5.34); fluoranthene, 2.37-fold (95% CI 1.02–5.48); pyrene, 2.41-fold (95% CI 1.04–5.62); and benzo(b)fluoranthene, 2.95-fold (95% CI 1.27–6.86). In BKMR, although the risk for NTD was increased with PAH concentrations above the 50th percentile, it was only when PAH concentrations exceeded the 65th percentile, the association between PAH concentration and risk for NTDs became statistically significant, while no statistical association between a single compound and NTD risk was observed when the remaining nine PAHs were taken into consideration simultaneously. The use of an indoor stove for heating and use of coal or wood for cooking were positively correlated with PAH levels in cord tissue. In conclusion, these results show that prenatal PAH exposure may be a risk factor for NTDs in offspring.