Levels of polycyclic aromatic hydrocarbons in umbilical cord and risk of orofacial clefts

Polycyclic aromatic hydrocarbons (PAHs), which are ubiquitous in the environment, have been found to cause orofacial clefts (OFCs) in mouse model. However, evidence from the human study with markers of intrauterine exposure is absent. We explored the associations between the levels of sixteen PAHs in umbilical cord tissue and risk for OFCs using multivariable logistic models and Bayesian Kernel Machine Regression (BKMR). This case-control study included 89 OFC cases and 129 controls without congenital malformations. Concentrations of PAHs in umbilical cord tissue were detected using gas chromatography coupled to triple quadrupole tandem mass spectrometry. The median levels of ΣPAHs, Σlow molecular weight polycyclic aromatic hydrocarbons, and Σhigh molecular weight polycyclic aromatic hydrocarbons were all higher in cases of total OFCs and its subtypes than in controls, although the differences were not statistically significant. No statistical associations between levels of PAHs in umbilical cord tissue and risk for OFCs were observed in either multivariable logistic models or BKMR models. Maternal using a stove for heating and lower frequency of ventilation in the bedroom/living room, and consumptions of fresh green vegetables were positively correlated with levels of PAHs in umbilical cord. In conclusion, our results did not suggest that in utero exposure to PAHs were associated with the risk for OFCs, in estimating whether single effect of PAHs or joint effects of multiple PAHs.