Prenatal Exposure to Neonicotinoids and the Associations with Neonatal Birth Outcomes and Maternal Health in South China

Neonicotinoids (NEOs) are a class of novel insecticides which are used for pest control and crop protection all over the world. However, there is only scarce research concerning whether NEO exposure adversely affects pregnant women. For this reason, we quantified twelve NEOs, including six parent NEOs (p-NEOs) and six characteristic metabolites (m-NEOs), in 600 serum samples from pregnant women in south China. The detection rates of all target NEOs exceeded 60%, and the median concentrations ranged from 0.02 to 0.33 ng/mL. Dinotefuran (DIN) and N-desmethyl-thiamethoxam (N-dm-THM) were the predominant NEOs detected in serum samples. The m-NEOs showed higher serum concentrations than p-NEOs, which indicates that NEOs are more commonly present in metabolite form in the human body. Bayesian kernel machine regression (BKMR) and quantile-based g-computation (QGC) models revealed that co-exposure to the examined contaminants was related to elevated neonatal birth size, along with the trimester-specific effects on the exposure-outcome links. Furthermore, exposure to NEOs showed inverse relationships with maternal free thyroxine (FT4) levels. The presented neonatal and maternal health risks associated with NEO exposure warrant further research into the underlying biochemical mechanisms.