Maternal exposure to polystyrene nanoplastics impacts developmental milestones and brain structure in mouse offspring

The presence of microplastics and nanoplastics (NPs) has recently been reported in human blood and tissues, raising concerns about their potential impacts on human health and fetal development. In this study, we investigated the effects of maternal exposure to NPs on the timing of developmental milestones and on brain structure using experimental mice. Healthy, pregnant CD-1 dams were given 10⁶ ng L⁻¹ of 50 nm polystyrene NPs in drinking water throughout gestation and lactation and the postnatal behavior and neuroanatomy of the offspring were studied. We found that NPs exposure resulted in earlier time to eye opening in male offspring but not in females (p = 0.01). 3D high-resolution ex vivo magnetic resonance imaging (MRI) revealed that offspring exposed to NPs had focal differences compared to controls in multiple brain structures that are involved in motor function, learning and memory, and physiological functions including the motor cortex, hippocampus, hypothalamus, medulla, and olfactory bulb. Several of these MRI-detectable neuroanatomical changes were dependent on sex. Our study demonstrates that maternal exposure to NPs results in abnormal postnatal brain development in the mouse. Further investigations are needed to determine the mechanisms whereby NPs exposure during fetal development may adversely affect dimensions of brain function in a sex-dependent manner.